US2847912A - Paper making machine drive and control means therefor - Google Patents

Description

g- 19, 1958 E. D. BEACHLER 2,847,912

PAPER MAKING MACHINE DRIVE AND CONTROL MEANS THEREFOR Filed Aug. 4, 1951 4sheets-sueet 1 g Q w W sxcmnou a. CONTROL UNIT ,4 I 95 91 $90 mass secnou EXCITATION 8: CONTROL UNIT "67 82 FORMING SECTION 44 ITZVE Til ET" Edward D. Bead/21er- Aug. 19, 1958 E. D. BEACHLER PAPER MAKING MACHINE DRIVE AND CONTROL MEANS THEREFOR .4 Sheets-Sheet 2 Filed Aug. 4, 1951 .223 JOmPZOo m ZOFCQCOXm ZOEbww wwmma Ii'ZZ E T727: 7 Edward D. Bean/2161" 1958 E. D. BEACHLER PAPER MAKING MACHINE DRIVE AND CONTROL MEANS THEREFOR Filed Aug. 4, 1951 4 Sheets-Sheet 3 .523 Joy-F200 m ZOTZELOXU zOcbww QZEEOm T 5 l I 1 I I 1 m 2 b m H w w m m H mmw kw y D g IR H M w M m @w I M @w SN g r I w 9& Q. M 3

' E. D. BEACHLER Aug. 19, 1958 PAPER MAKING MACHINE DRIVE AND CONTROL MEANS THEREFOR 4 Sheets-Sheet 4 Filed Aug. 4, 1951 .523 JOmPZOO I ZOEbmw l: JY'EL .LZLCIL Edward .D. Beau/226 1" Z Z155 United States Patent PAPER MAKING MACHINE DRIVE AND CONTROL MEANS THEREFOR Edward D. Beachler, Beloit, Wis., assignor to Beloit Iron Works, a corporation of Wisconsin Application August 4, 1951, Serial No. 240,353

4 Claims. (Cl. 92--38) This invention relates to a paper making machine drive and control means therefor and more particularly to a Fourdrinier type of paper making machine adapted to operate with either an open or a closed web draw between the forming section and the press section and drive control means maintaining stable and efiicient operation of the machine and preventing damage to the paper or the machine.

Specifically, the Fourdrinier paper making machine transfers a moist paper sheet from its forming surface to its press section via a pick-up felt preferably trained about a suction pick-up roll disposed adjacentthe forming surface. The forming surface is preferably driven and pulled over suction boxes by a suction couch roll and a turning roll providing a run therebetween coacting with the pick-up felt. The press section may include a suction transfer press receiving the pick-up felt and a first press felt through the nip thereof whereupon the sheet is transferred by suction at the nip to the press felt which carries the sheet through the first nip of a clover-leaf press. The sheet is carried by the upper roll of this press to the second roll and is transferred to a second press felt by the suction of the second press roll. The sheet is then fed to other machine sections, such as the drier section.

Machines of this type have heretofore been provided and adapted for open draw operation in which the pickup felt and the pick-up roll are spaced from the forming surface so that an unsupportedsheet will result and tension on this sheet draw will be controlled by the difference in speed of operation of the forming surface and the pick-up press section. Such open draw machines have been provided with speed-responsive means in the forming section drive adapted to maintain constant wire speed and similar speed-responsive means in the press section drive adapted to maintain the speed of the pick-up felt constant. Such open draw machines have not been operable with a closed draw since, with closed draw operation, power can be transferred between the forming sectionand the press section through the web and felt so that even the slightest difference in the speed settings of the two sections will result in placing the entire load on the drive for the section which has the higher speed. This will result ina power transfer through the web from one section to the other and in scuffing of the web and unsatisfactory operation of the machine.

According to this invention, a paper making machine is provided in which the pick-up roll is adjustably mounted for movement toward or away from the wire so that the machine can be operated with either an open or a closed web draw between the forming and the press section. Speed-responsive means are provided to drive the rolls of the press section at substantially constant speed. The 'drive for the forming section is also provided with speed-responsive means such that the wire is driven at constant speed when the machine is operated with an open web draw. In addition, the drive for either the press section or the forming section, preferably Patented Aug. 19, 1958 the forming section, incorporates load-responsive means selectively actuatable to provide a drooping speed-load characteristic when the machine is operated with a closed web draw.

With this drooping speed-load characteristic of the forming section, the speed of the forming section will increase when power is transferred from the press section drive through the felt, web and wire to the forming section drive and will decrease when power is transferred from the forming section drive through the wire, web and felt to the press section drive so that the forming section drive will automatically adjust itself to drive the wire at substantially the speed of the pick-up felt with minimum power transfer between the two drives through the web, thus preventing scufling of the web. This invention accordingly provides a paper making machine selectively operable with either a closed or an open web draw between the forming and press sections.

In a preferred type of machine, stock comprising paper pulp suspended in water is supplied onto a wire. The wire passes over evacuated boxes which remove a portion of the water and pack the pulp fibers to form a web.- Drive for the wire is provided by a couch roll and a wire turning roll about which the wire is entrained. The couch roll is preferably provided with suction means for further removal of water and packing of the fibers and for increasing the traction between the roll and the wire. At a point between the suction couch roll and the wire turning roll, the web is transferred from the wire to a pick-up felt of the press section.

A feature of the present invention is in the control of the drive of the couch roll and the wire turning roll in a manner such that the proper speed of the wire and the proper load division between the couch roll and the wire turning roll result.

Another feature of the present invention is in the control of the forming section drive in accordance with the vacuum in the wire run to prevent excessive power out- A preferred forming section drive, according to this invention, includes a pair of electric motors for driving the couch roll and the wire turning roll. Electrical excitation forthe couch roll motor and the wire turning roll is supplied by a forming section control unit. The couch roll is so controlled as to act as the speed-determining roll, while the wire turning roll acts as a helper drive.

A device responsive to the speed of the couch roll is connected to the control unit and acts to'maintain wire speed constant when open web draw operation is desired. When closed web draw operation is desired, means responsive to the current through the couch roll motor is switched into the control unit circuit in a manner such that a drooping speed-load characteristic is obtained. As pointed out above, this drooping speed-load characteristic results in a stable load division between the forming section and the press section when the machine is operated with aclosed web draw.

In normal operation, a fairly high torque is required to drive the wire, and the current through the wire turning roll motor is maintained at a substantially constant value by the control unit so that a substantially constant value of torque is applied to the wire by the turning roll and so that the tension of the wire between the couch roll and the turning roll is constant. With only this constant current control of the wire turning roll motor, if the torque necessary to drive the wire should drop below the above-mentioned value of torque, the wire turning rollmotor would attempt to take all the load and drive the couch roll and couch roll motor through the wire and undue wear on and damage to the wire might result. To prevent this, means are provided in the control unit for reducing the wire turning r011 motor excitation when the speed control circuit of the couch roll indicates that a high torque is not necessary to drive the wire.

If the web is lost from the wire, the load on the forming section drive means is greatly reduced. Accordingly, by this invention, load responsive means including means responsive to loss of web from the wire are provided for limiting the torque supplied to the rolls, of the forming section. Further, since the vacuum. in the suction boxes and couch roll is built up as the amount of stock on the wire increases, the stock has a controlling effect on the vacuum and the torque input is therefore regulated by the amount of stock on the wire.

In a preferred forming section drive of this invention, the excitation of the couch roll motor and the wire turning roll motor are limited in accordance with the vacuum in the couch roll which is responsive to the amount of stock on the wire. This is accomplished by an electrical device responsive to couch roll vacuum which is connected to the control unit.

In a modified form of forming section drive of this invention, the wire turning roll motor is controlled to determine the speed of the wire, and the couch roll motor acts as a helper drive. A speed-responsive device is connected to the wire turning roll and acts to control the excitation of the wire turning roll motor so that, when the paper machine is operated with an open web draw between the forming section and the press section, the speed of the wire will be substantially constant. When a closed web draw operation is desired, a current-responsive device in circuit with the wire turning roll motor is connected to control the excitation of the wire turning roll motor and to provide a drooping speed-load characteristic. Current-responsive means in circuitwith the couch roll drive motor control the excitation of the motor in a manner such that the current through the motor and hence the torque output of the motor are substantially constant. To prevent slippage of the wire on the couch roll and prevent the couch roll motor from running away with the load when the vacuum in the couch roll and the evacuated boxes drops due to loss of the web from the wire, a device responsive to the vacuum in the couch roll is connected to control the excitation of the couch roll motor in accordance with the vacuum.

In another modification of forming section drive of this invention, the wire turning roll is the speed-determining roll. The wire turning motor is controlled by a speedresponsive device in a manner such that the speed of the wire is substantially constant when open web draw operation is desired and is controlled by a current-responsive device in a manner such that a drooping speed-load characteristic is provided when closed web draw operation is desired. The couch roll acts as a helper drive, and current-responsive means in circuit with the couch roll drive motor control the excitation of the motor in a manner such that the current through the motor and the torque output of the motor are substantially constant. To prevent the couch roll motor from running away with the load when the load is light due to loss of web from the wire, load-responsive means including an electrical device responsive to the vacuum in the evacuated boxes controls the excitation of the couch roll motor and reduces the excitation of the motor when the vacuum in the evacuated boxes drops due to loss of web from the wire.

An object of this invention, accordingly, is to provide a paper making machine selectively and efliciently operable with either an open web draw or a closed web draw between the forming section and the press section.

Another object of this invention is to provide a paper ;making machine in which the drive of the rolls of the forming section is so controlled as to maintain a proper load division between the rolls and so as to prevent damage to and mal-operation of the machine.

Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the invention and in which:

Figure 1 illustrates, in diagrammatic form, a paper making machine constructed according to this invention incorporating a forming section excitation and control unit and a press section excitation and control unit;

Figure 2 is a circuit diagram of the motor field connections;

Figure 3 is a circuit diagram of the press section excitation and control unit;

Figure 4 is a circuit diagram of the forming section excitation and control unit;

Figure 5 is a schematic diagram of a modified form of forming section drive; and

Figure 6 is a schematic diagram of another modified forming section drive.

Referring to the drawings, reference numeral 10 designates a wire providing a foraminous surface. Paper stock is supplied to the wire 10 by apparatus not shown. The wire 10 passes over a plurality of evacuated boxes 11 which remove water from the stock and pack the paper fibers to form a web. The boxes 11 are evacuated through a common suction header 12.

The wire 10 is entrained about and driven by a couch roll 13 and a wire turning roll 14. For further removal of water and packing of the fibers and to increase traction between the wire and the couch roll, the couch roll 13 preferably has vacuum or suction means incorporated therein as diagramatically illustrated and as designated by reference numeral 15.

The paper web or sheet is transferred from the wire 10 to a looped pick-up felt 16 at a point between the couch roll 13 and the wire turning roll 14. Disposed in the loop of the pick-up felt 16 for driving of the same are a pick-up roll 17 and a top press roll 18. The pick-up roll 17 is adjustably mounted for movement toward and away from the wire 10 so that the machine can be operated with either a closed web draw or an open web draw between the wire 10 and the pick-up felt 16. The full line position of the pick-up roll 17 in Figure l is the closed web draw position while the dotted line position is the open web draw position.

For adjusting the position of the pick-up roll 17, the pick-up roll has projecting shaft portions 19 (only one being illustrated in Figure 1), each journaled in a bearing block 20 which is slidably guided in a fixed frame 21. A jack screw 22 having a crank handle 23 is threaded into each bearing block 20, rotation of the crank handles 23 thereby serving to move the pick-up roll 17 toward or away from the wire 10.

The pick-up roll 17 preferably has vacuum or suction means incorporated therein as diagrammatically illus-. trated and as designated by reference numeral 24 to aid in the transfer of the web from the wire 10 to the pick-up felt 16. 1

The web or sheet is transferred to a first looped press felt 26 at a point between the top press roll 18 and a transfer press roll 27 which is disposed in the loop of the first press felt 26. The transfer press roll 27 preferably has vacuum or suction means 28 incorporated therein, as diagrammatically illustrated, to aid in the transfer of the web from the pick-up felt 16 to the first press felt 26. The transfer press roll 27 preferably has vacuum or suction means 28 incorporated therein, as diagrammatically illustrated, to aid in the transfer of the web from the pick-up felt 16 to the first press felt 26. The sheet is then transferred from the first press felt 26 to an upper roll 30 of a clover-leaf press at a point between the upper roll 30 and a first lower clover-leaf press roll 31 which is disposed in the loop of the first press felt 26 and in driving engagement therewith. To increase the traction between the first press felt 26 and the first lower clover-leaf press roll 31, the roll 31 preferably has suction or vacuum means 32 incorporated therein as diagrammatically illustrated.

The sheet is next transferred from the upper cloverleaf press roll 30 to a second press felt 33 at a point between the upper roll 30 and a second lower press roll 34. The second lower press roll 34 preferably has vacuum or suction means 35 incorporated therein to aid in the transfer of the web thereto and to increase the traction between it and the second press felt 33.

The couch roll 13 and the wire turning roll 14 of the web-forming section are separately driven by motors M1 and M2, respectively, preferably direct-current electric motors. The pick-up roll 17, the top press roll 18, the transfer press roll 27, the first clover-leaf press roll 31, and the second clover-leaf press roll 34 of the press section are driven by motors M3, M4, M5, M6 and M7, preferably direct-current electric motors. The motors M1, M2, M3, M4, M5, M6 andM7 have fields 36, 37, 38, 39, 40, 41 and 42, respectively, which are separately excited from a pair of busses 43 and 44 through variable resistors 45, 46, 47, 48, 49, 50 and 51, respectively, as shown in Figure 2. The busses 43 and 44 may be connected to any desired source of D.-C. voltage.

As shown in Figure 1, the couch roll drive motor M1 and the wire turning roll drive motor M2 are connected to and excited from a forming section excitation and control unit generally designated by reference numeral 53. One terminal of the couch roll motor M1 is connected directly to a terminal 54 on the forming section excitation and control unit, and the other terminal of the couch roll motor M1 is connected through a resistor 55 to a terminal 56 on the forming section excitation and control unit. The armature terminals on the wire turning roll motor M2 are connected to terminals 57 and 58 on the forming section excitation and control unit.

The junction between the resistor 55 and the motor M1 is connected through a lead 59 to a terminal 60 on the excitation and control unit. The voltage between the terminals 56 and 60 is thus proportional to the couch roll motor M1 current and is utilized in the excitation and control unit to provide a drooping speed-load characteristic when the paper machine is operated with a closed web draw.

The forming section excitation and control unit 53 also controls the excitation of the couch roll motor M1 and the wire turning roll motor M2 in accordance with Wire speed. For this purpose, a tachometer generator T1 is driven from the couch roll 13 and is connected through leads 61 and 62 to terminals 63 and 64, respectively, on the forming section excitation and control unit 53.

Direct-current power for the excitation and control unit 53 may be supplied to terminals 65, 66 and 67 thereon through busses 68, 69 and 70, respectively, which may be connected to any desired D.-C. supply. The bus 68 is a negative or common bus, the bus 69 preferably is approximately 105 volts positive with respect to bus 68, and the bus 70 is preferably approximately 210 volts with respect to the common lead 68.

The forming section excitation and control unit 53 also controls the excitation of motors M1 and M2 in ac cordance with the vacuum in the couch roll 13. For this purpose, a vacuum-controlled potentiometer generally designated by numeral 71 is employed. This device may be of any desired construction but, as diagrammatically illustrated, it has a resistance element 72 connected between terminals 73 and 74 and a movable contact 75 connected to the terminal 76. The movable contact 75 is connected to a piston 77 movable in a cylinder 78 which is connected through a suction line 79 to the suction or vacuum means 15 in the couch roll 13. The vacuum of the couch roll 13 thus determines the position of the movable contact 75 with respect to the resistance element 72. The terminal 76, which is connected to the movable contact 75, is connected through a line 81 to a terminal 82 on the forming section excitation and control unit 53. The terminals 73 and 74 of the potentiometer device 71 are connected to the positive and negative leads 78 and 68, respectively, of the D.-C. supply so that the potential of the movable contact 75, and hence the potential of the terminal 82 on the control unit, is determined by the vacuum present in the couch roll 13.

it will thus be seen that the forming section excitation and control unit may control the excitation of the couch roll motor M1 and the excitation of the wire turning roll motor M2 in accordance with (1) couch roll motor M1 current, (2) couch roll vacuum and (3) couch roll speed. The forming section excitation and control unit will be described in detail hereinafter but, for clarity, the press section drive control will be first described.

The motors M3, M4, M5, M6 and M7 of the press section are all connected in parallel to busses 83 and 84 which are connected to terminals 85 and 86, respectively, on a press section excitation and control unit 87. The rolls of the press section-are preferably driven at substantially constant speed. For this purpose, a tachometer generator T 2 is driven from the second clover-leaf press roll 34 and is connected through leads 88 and 89 to terminals 98 and 91, respectively, on the press section excitation and control unit 87. The control unit 87 is so controlled by the tachometer generator voltage that the speed of the second clover-leaf press roll 34 is maintained substantially constant. The speed of the pick-up roll 17, the top press roll 18, the transfer press roll 27, and the first clover-leaf press roll 31 may be adjusted in relation to the speed of the second press roll 34 by means of the field resistors 47, 48, 49 and 50, respectively, so that all the rolls of the press section will be driven at the desired constant speeds.

Direct-current power for the press section excitation and control unit 87 is supplied from the same busses 68, 69 and 78 which supply power to the forming section excitation and control unit 53 and which are connected to terminals 93, 94 and 95, respectively, on the press section excitation and control unit.

As will appear later in the detailed descriptions of the forming section control unit and the press section control unit, a source of constant voltage is highly advantageous in the speed control circuits thereof. This is provided from an adjustable and regulated standard voltage device generally designated by reference numeral 96 which has a positive terminal 97 connected to the lead 69 and a negative terminal 98 connected to a terminal 99 on the forming section excitation and control unit 53 and a terminal 100 on the press section excitation and control unit 87. The device 96 may be of any desired construction and is preferably adjustable so that the speed of the rolls of both the forming section and the press section may be simultaneously varied to vary the speed of the entire machine.

Referring now to Figure 3, the press section excitation and control unit 87 includes a generator 101 connected to the terminals 85 and 86 which, as pointed out above, are connected to all the drive motors of the press section. The generator 101 has a field 102 which is connected to armature terminals of a generator 103 which in turn has a control field 184. The generator 103 preferably has a very high amplification factor, that is, a large change in output from only a small change in field current. As shown, it may have one pair of opposite armature brushes connected together and a compensating field 103a in the load circuit which, in the proper design, will provide the high amplification factor required. Generators of this type are commonly called amplidynes.

The generator 101, the generator 103 and other generators of the machine, to be later referred to, are preferably all driven by a single motor or other power source,

not shown, but, of course, any suitable drive means may be employed.

The control field 104 of the amplidyne or generator 103 is connected between the positive terminal 95 and a plate 105 of an electronic amplifier tube 106, preferably a high-vacuum triode also having a grid 1137 and a cathode 108 which may be either directly or indirectly heated. The cathode 103 is connected to the positive terminal 94. As pointed out above, the leads 69 and 70 preferably have positive potentials of 105 volts and 210 volts, respectively, in relation to the common lead 68 so that the terminal 94 is approximately 105 volts positive with respect to the terminal 93 and the terminal 95 is approximately 210 volts positive with respect to the terminal 93. Thus, the plate voltage of the tube 106 is approximately 105 volts. It will be apparent that a variation in the potential of the grid 107 of the tube 106 Will vary the plate current of the tube which flows through the field 104 of the generator 103.

The potential of the grid 107 of the tube 106 is controlled in accordance with the speed of the second cloverleaf press roll 34. For this purpose the tachometer T2 driven by the roll 34 is connected to the terminals 90 and 91, as pointed out above. The terminal 90 is connected to the terminal 94 and the terminal 91 is connected through a resistor 109 to the grid 110 of an electronic amplifier tube 111, preferably a high-vacuum triode also having a plate 112 and a cathode 113. The plate 112 is connected through a resistor 114 to the positive terminal 95 and is also connected directly to the grid 107 of the vacuum tube 106. The cathode 113 of the tube 111 is connected through a resistor 115 to the negative or common terminal 93. The grid 110, as well as being connected through the resistor 109 to the terminal 91, is connected through a resistor 116 to the terminal 100 which, as pointed out above, is connected to the negative terminal of the adjustable and regulated standard voltage device 96. The terminal 91 is positive with respect to the terminal 94 by the amount of voltage developed by the tachometer generator T2, and the terminal 100 is L negative with respect to the terminal 94 by the amount of voltage provided by the standard 96. The voltage of the standard 96 is preferably in the order of 200 volts and the voltage developed by the tachometer generator T2 when operating at normal speed is also preferably in the order of 200 volts so that the two voltages substantially balance and so that the potential of the grid 110 of the tube 111 is approximately the same as the potential of the terminal 94, that is, approximately 105 volts positive with respect to the terminal 93. With this circuit, a small change in the speed of the tachometer generator T2 will effect a relatively large change in the potential of the grid 110.

The circuit operates as follows: if the speed of the second clover-leaf press roll 34 should decrease due to increased load, for example, output of the tachometer generator T2 will also decrease and the potential of the grid 110 of the tube 111 will be decreased. This will result in decreased current flow through the tube 111, a decreased voltage drop across the resistor 114, and an increased potential of the grid 107 of the tube 106. The corresponding increase in the current through the tube 106 and through the field 104 of the generator 103 will increase the voltage output of the generator 103 and the field excitation of the generator 101, thus increasing the voltage supplied by the generator 101 to the motors of the press section to bring these motors back up to the proper speed. Conversely, a decreased load on the motors of the press section will, throught the control unit, decrease the excitation of the motors so that a substantially constant speed will result regardless of variations in load on the rolls of the press section.

Referring now to Figure 4, which is the circuit diagram for the forming section excitation and control unit, a generator G1 is provided for exciting the couch roll drive motor M1 and a generator G2 is provided for driving the wire turning roll drive motor M2. The armature brushes of the generator G1 are connected through lines 119 and 120 to the terminals 56 and 54, respectively. The generator G1 has a field 121 connected to the armature terminals of a generator 122 which, in turn, has a field 123. The generator 122 preferably has a high amplification factor and may, as illustrated, have opposite armature brushes connected together and a compensating field 122a in the output circuit so that a small change in control field current will instantaneously produce a relatively large change in power output.

One terminal of the control field 123 is connected to a line 124 connected to the positive terminal 67 and the other terminal of the field 123 is connected to a plate 125 of an electronic amplifier tube 126, preferably a highvacuum triode also having a grid 127 and a cathode 128. The cathode 128 is connected through a resistor 129 to a bus 130 connected to the terminal 66.

The control grid 127 of the tube 126 is connected to a plate 131 of an electronic amplifier tube 132, preferably a high-vacuum triode also having a grid 133 and a cathode 134. The plate 131 is connected through a resistor 135 to the positive bus 124 and the cathode 134 is connected through a resistor 136 to a bus 137 connected to the negative or common terminal 65. The grid 133 of the tube 132 is connected through a resistor 138 to the terminal 64 and through a resistor 139 to the terminal 99. As pointed out above, the terminals 64 and 63 are connected to the tachometer generator T1. The terminal 63 is connected through a resistor 141 to the terminal 66.

The circuit thus far described operates as follows: the terminal 64 is positive with respect to the terminal 63 by the tachometer generator T1 voltage and the terminal 99 is negative with respect to the terminal 66 by the voltage of the adjustable and regulated standard 96, preferably approximately 200 volts. The tachometer generator voltage appearing between terminals 63 and 64 is approximately 200 volts when the couch roll 13 is driven at normal speed so that the potential of the grid 133 of the tube 132 is approximately the same as the potential of the terminal 66 which, as pointed out above, is preferably 105 volts positive with respect to the terminal 65. it will be apparent that, by using a tachometer generator with a large voltage output and balancing the tachometer generator output with the correspondingly large standard voltage, a small change in speed of the tachometer generator will effect a relatively large change in the potential of the grid 133.

If the speed of the couch roll 13 should decrease, the voltage of the tachometer generator T1 will decrease, the potential of the grid 133 of the tube 132 will decrease, the current through the resistor 135 will decrease, the potential of the grid 127 of the tube 126 will increase, the current through the field 123 of the generator 122 will increase, the output of the generator 122 will increase to increase the field excitation of the generator G1, the output of the generator G1 will increase to increase the excitation of the couch roll drive motor M1 and the couch roll 13 will be brought back up to speed. Conversely, an increase in the speed of the couch roll 13, through the action of the circuit, will decrease the excitation of the motor M1 to bring the couch roll back to the desired speed. Thus, the circuit operates to automatically compensate for any variations in load and maintains the speed of the couch roll 13 substantially constant.

Constant speed of the couch roll 13 through the action of this circuit is highly satisfactory when open web draw operation of the machine is desired. However, when closed web draw operation is desired, constant speed regulation of both the forming section and the press section is unsatisfactory because, since power can be transferred between the sections through the web, the speed-respon- 9 sive drive means of one or the other of the sections will attempt to take the entire load and transfer power through the web which will result in scufiing of the web and mal-operations of the machine. Consequently, provision is herein made for selectively imposing a drooping speedload characteristic on the forming section drive so that, when closed Web draw operation is desired, the speed of the forming section wire will be automatically adjusted with respect to the speed of the pick-up felt of the press section and the sections will be stable in operation with minimum power transfer through the Web therebetween.

According to this invention, means responsive to the load of the forming section control the drive of the forming section so that the speed is reduced as the load increases. For this purpose, the voltage appearing between the terminals 56 and 60, which is a function of the current through the couch roll drive motor M1, is used to control the excitation of the couch roll generator G1. The terminal 56 is connected through the line 119 to one armature termnial of the generator G1 and to one terminal of a control field 143 of a generator 144 and the terminal 60 is connected through a line 145 to the other terminal of the field 143, the field 143 thereby being excited in proportion to the current through the couch roll drive motor M1.

The generator 144 is preferably an amplidyne having one pair of opposite armature brushes connected together and having a compensating field 144a in the output circuit so that a small change in field excitation may instantaneously effect a relatively large change in power output from the other pair of armature brushes. The output of the generator 144 is connected to a potentiometer 146 having three movable contacts 147, 148 and 149. The contact 149 is connected to the bus 130 and the contact 148 is connected through a line 150 to one terminal of a switch 151. The other terminal of the switch 151 is connected to the terminal 63. It will be apparent that, when the switch 151 is closed, there will be a voltage across the resistor 141 equal to the voltage between the contacts 143 and 149 of the potentiometer 146 which, in turn, is proportional to the current through the couch roll drive motor M1.

This circuit operates to provide a drooping speedload characteristic in the following manner: when the load on the couch roll motor M1 increases, the current through the motor will increase, thus increasing the voltage output of the generator 144 and the voltage across the potentiometer 146, the voltage between the contacts 149 and 148 will increase, the voltage across the resistor 141 will increase, the positive potential of the grid 133 of the tube 132 will increase, the current through the resistor 135 will increase, the potential of the grid 127 of the tube 132 will increase, the current through the control field 123 of the generator 122 will decrease, the voltage output of the generator 122 and the field excitation of the generator G1 will decrease, and the voltage output of the generator G1 will decrease, thus decreasing the speed of the motor M1 and of the couch roll 13. The degree to which the speed is decreased with increasing load may be adjusted by adjustment of the movable contact 148 of the potentiometer 146 relative to the contact 149. A substantially constant speed of the couch roll 13 with variations in load or a drooping speed-load characteristic of the couch roll 13 may, of course, be selectively obtained by manual actuation of the switch 151 between open and closed positions.

An important feature of the present invention is in the control of the forming section drive in accordance with the vacuum in the wire run such that slippage of the wire cannot occur and such that the driving torque applied to the wire is limited when the vacuum in the wire run drops due to loss of the web from the wire so that damage to the wire and unsatisfactory operation of the machine are prevented.

As previously described, the movable contact 75 of the potentiometer device 71 is controlled in accordance with the vacuum in the couch roll 13 so that the potential of the terminal 82 on the forming section excitation and control unit 53 increases when the vacuum in the couch roll 13 decreases and decreases when the vacuum in the couch roll 13 increases. The potential of the terminal 82 is combined with a potential determined by the current through the couch roll drive motor M1 to control an electronic amplifier tube in the forming section excitation and control circuit and limit the excitation of the forming section drive motors when the excitation of the drive motor is excessive in relation to the vacuum in the wire run.

As shown in Figure 4, the terminal 82 is connected through a lead 153 to one terminal of a resistor 154. The other terminal of the resistor 154 is connected through a resistor 155 to the movable contact 147 on the potentiometer 146. The potential of the junction between the resistors 154 and 155 is thus determined by the vacuum in the couch roll and the current through the couch roll motor M1. This junction is connected through a lead 156 to a grid 157 of an electronic amplifier tube 158, preferably a high-vacuum triode also having a plate 159 and a cathode 160. The plate 159 is connected to the grid 127 of the tube 126 and the cathode 160 is connected through a resistor 161 to the bus 130.

This circuit for controlling excitation in accordance with the vacuum in the wire run operates as follows: with the web on the wire and normal vacuum in the couch roll 13, the potential of the terminal 82 is sufficiently negative with respect to the potential of the contact 147 of the potentiometer 146 for the plate current of the tube 158 to be cut off due to the negative bias on the grid 157. If the potential of the terminal 82 should increase due to a reduction in the vacuum in the couch roll 13 and/or if the current through the motor M1 is increased in relation to the vacuum, the potential of the grid 157 of the tube 158 may increase to a point where the tube will conduct, thus increasing the current through the resistor 135, decreasing the potential of the grid 127 of the tube 126, decreasing the current through the field 123 of the generator 122, decreasing the output of the generator 122 and the field excitation of the generator G1 and decreasing the output of the generator G1 so that the excitation of the couch roll drive motor M1 will be decreased and so that the drive of the wire is not excessive in relation to the vacuum in the wire run.

The wire turning roll 14 is so driven by the motor M2 as to act as a helper drive for the couch roll 13. As shown in Figure 4, a D. C. generator G2 has one brush connected to the terminal 57 through a lead 163,

' the other brush being connected through a resistor 164 to the terminal 58. The generator G2 has a field 165 connected to and excited by a generator 166. The generator 166 is preferably an amplidyne having one pair of opposite armature brushes connected together and a compensating field 166a in the output circuit so that a small change in field excitation will result in a large change in power output. This generator 166 has two control fields 167 and 168.

To excite the control field 167, a pair of potentiometers 169 and 170 having movable contacts 171 and 172, respectively, are series connected across the generator G2. The contact 171 is connected directly to one output brush of the generator G1 and the contact 172 is connected through the control field 167 of the generator 166 to the other terminal of the generator G1.

The field 167 acts to control the excitation of the generator G2 in a manner such that the proper load division between the couch roll motor M1 and the wire turning roll motor M2 will be maintained. When the torque required to drive the wire is decreased, the 'voltage output of the generator G1 will be decreased through the action of the speed sensitive means con- ;trolling the excitation thereof. This reduction in the output voltage of the generator G1 will result in decreased current flow through the control field 167, decreased output of the generator 166, decreased field excitation of the generator G2 and decreased excitation of the wire turning roll drive motor M2. Con versely, increased load on the couch roll drive motor M1 and the resultant increased voltage output of the generator G1 will result in increased current flow through the control field 167, increased output of the generator 166, increased field excitation of the generator G2 and increased excitation of the wire turning roll drive motor M2. The circuit thus acts to divide the load between the couch roll drive motor M1 and the wire turning roll drive motor M2. This is particularly important when very little power is required to drive the wire as, for example, when there is no web on the wire, since the wire turning roll M2 is prevented from attempting to take the entire load and from driving the wire at a speed greater than the desired speed.

The control field 168 of the generator 166 is controlled in response to the current through the couch roll drive motor M1 in a manner such that, at very light loads on the motor M1, the excitation of the generator G2 is decreased and the wire turning roll drive motor M2 is prevented from running away with the load. As shown in Figure 4, a potentiometer 174 having a movable contact 175 and a potentiometer 176 having movable contacts 177 and 178 are connected in series between the positive bus 124 and the negative or common bus 137. The contact 175 is connected through a rectifier 179 and the control field 168 to the contact 177. The contact 175 is also connected'through a rectifier 180 to the lead 156 which, as described above, is connected to the terminal 60. The contact 178 is connected through a lead 181 to one brush of the generator G1.

The contact 178 is negative with respect to the lead 145 by the amount of voltage across the resistor 55 in series with the couch roll drive motor M1. With'normal load on the couch roll drive motor M1, the current therethrough will be sufficiently high for the potential of the lead 145 to be positive enough with respect to the potential of the contact 178 for the rectifier 180 to be blocked off. With this normal load on the couch roll drive motor M1, the current flow through the field 168 of the generator 166 will be constant as determined by the relative potentials of the contacts 175 and 177. However, if the load on the couch roll drive motor M1 should decrease to a low value, the lead 145 will be only slightly positive with respect to the contact 178 and current may flow through the rectifier 180 to divert.

current flow from the control field 168 and reduce the excitation of the generator 166, thus reducing the excitation of the generator G2 and the excitation of the wire turning roll drive motor M2 to prevent the motor M2 from running away with the load.

It is desirable that the tension on the wire between the couch roll 13 and the wire turning roll 14 be constant. For this purpose, provision is herein made for maintaining the current through the wire turning roll motor M2, and hence the torque supplied thereby and the tension on the wire, constant during normal operation when the load is comparatively high. Referring to Figure 4, a potentiometer 183 having a movable contact 134 is connected between the positive bus 124 and the negative or common bus 137. The contact 184 is connected through a rectifier 185 to one terminal of the resistor 164. When the current through the wire turning roll motor increases to a predetermined value, the voltage across the resistor 164 will be such as to allow current flow through the blocking rectifier 185. The return path for the current flow through the blocking rectifier 185 will be from the contact 178 through the lead 181 and through the control field 167 of the generator 166; The direction of this current flow Will be such as to reduce the total current flow through the field 167, thus reducing the excitation of the generator G2 and the current flow through the wire turning roll motor M2. Accordingly, the current flow through the motor M2 will be limited to a predetermined value as determined by the positions of the contacts 184 and 178. The current flow limit is preferably such that it is effective atloads higher than a fraction of the normal operating load so as to maintain constant motor M2 current with normal loads and the resultant constant torque and constant wire tension.

In summary, the preferred paper making machine of Figures 1 through 4 may be selectively operated with either a closed or an open web draw between the forming section and the press section by adjusting the position of the pick-up roll and actuating the switch 151. The couch roll is the speed-determining roll and the wire turning roll acts as a helper drive, the excitation of the wire turning roll drive motor being so controlled that it provides constant torque in the normal range of loads but, below the normal range of loads, a proper load division between the wire turning roll and the couch roll is maintained. A protective circuit operates at light loads to prevent the wire turning roll motor from supplying excessive torque and from running away with the load. A potentiometer controlled in accordance with the couch vacuum is connected to limit the forming section excitation so that damage to and mal-operation of the machine is prevented.

Although, for closed draw operation, the forming section drive is herein provided with a drooping speedload characteristic, it will be apparent that the press section 'drive means could, instead, be provided with the drooping speed-load characteristic by a circuit similar to the forming section circuit shown and described.

Referringnow to Figure 5, a modified forming section drive is illustrated. In this modified drive, the wire turning roll 14 is the speed-determining roll and the couch roll 13 is so excited as to act as a helper drive.

It will be noted that the tachometer T1 is connected to and driven by the wire turning roll 14. The excitation of the wire turning roll drive motor M2 may be so controlled by means of the tachometer T1 as to provide constant wire speed when an open web draw between the forming section and the press section is desired. When closed web drawing operation is desired, means responsive to the current through the wire turning roll drive motor M2 controls the excitation of the motor in a manner such that a drooping speed-load characteristic is provided. The field 165 of the generator G2 is connected to the armature terminals of a generator 187 The generator 187 has a control field 188 and is preferably an emplidyne having one pair of opposite armature brushes shorted together and a compensating field 187a in the output circuit, as shown, so that a small change in field current will effect instantaneously a relatively large change in output.

One terminal of the field 188 is connected to the positive bus 70. As in the preferred machine described above and illustrated in Figures 1 through 4, the bus 70 preferably is approximately 210 volts positive with respect to'the negative or common bus 68, while the bus 69 is preferably volts positive with respect to the common bus 68. The other terminal of the field 188 is connected to a plate 189 of an electronic amplifier tube190, preferably a high-vacuum triode also having a grid 191 and a cathode 192. The cathode 192 is connected through a resistor 193 to the bus 69. The grid 191 is connected to a plate 194 of an electronic amplifier tube 195,'preferably a high-vacuum triode also havmg a grid 196 and a cathode 197. The plate 194 is connected through a resistor 198 to the bus 70 and the cathode 197 is connected through a resistor 199 to the bus 68. The grid is connected through a resistor 201 to one terminal of the tachometer T1 and through 13 a resistor 202 to the negative terminal 98 of the adjustable and regulated standard voltage supply 96. The other terminal of the tachometer generator T1 is connected through a resistor 203 to the bus 69 and the positive terminal 97 of the standard voltage supply 96 is also connected to the bus 69.

As with the preferred forming section drive circuit of Figures 1 to 4, the output of the tachometer generator T1, in normal operation, and the voltage of the standard voltage supply 96 are both approximately 200 volts, and they are connected in opposition so that the potential of the grid 196 is approximately the same as the voltage of the bus 69 and so that small change in the speed of the tachometer generator T1 will result in a relatively large change in the potential of the grid 196. An increase in the speed of the wire turning roll 14 will increase the output voltage of the tachometer generator T1 and the potential of the grid 196, decrease the potential of the grid 191, decrease the field excitation and output of the generator 187, decrease the field excitation of the generator G2 and decrease the excitation of the motor M2 so that the speed of the wire turning roll will be reduced down to the desired speed. Thus the wire turning roll 14 will be driven at substantially constant speed regardless of load variations,

as is highly advantageous when open web draw operation is desired.

To provide a drooping speed-load characteristic for closed web draw operation, a resistor 205 is connected in series with the motor M2 and in parallel with a control field 206 of a generator 207. The current through the control field 206 will thus vary proportionately to the current through the wire turning roll drive motor M2.

The generator 207 preferably is an amplidyne having one pair of opposite armature brushes connected together and having a compensating field 207a so that a small change in field excitation will instantaneously elfect a relatively large change in output. The output armature terminals of the generator 207 are connected to a potentiometer 208 having a movable contact 209 and the negative output terminal of the generator 207 is also connected to the bus 69. The contact 209 is connected through a lead 210 to one terminal of a switch 211. The other terminal of the switch 211 is connected to the juncture between the resistor 203 and the tachometer generator T1.

When the switch 211 is closed, the voltage across the resistor 203 will be proportionate to the voltage output of the generator 207 which is, in turn, proportionate to the current through the wire turning roll drive motor M2. It will be noted that the resistor 203 is in series with the tachometer generator T1. When the current through the wire turning roll drive motor increases due to increased load, the voltage across the resistor 203 will increase and the potential of the grid 196 of the tube 195 will increase, the potential of the grid 191 of the tube 190 will decrease, the field current and the output of the generator 187 will decrease and the field current and the output of the generator G2 will decrease, thus decreasing the voltage applied to the motor M2 and the speed thereof. Accordingly, a constant speed characteristic for open web draw operation or a drooping speed-load characteristic for closed web draw operation may be selectively provided by closing or opening the switch 211.

In the modification of Figure 5, the couch roll 13 acts as a helper drive for the speed-determining wire turning roll 14. Provision is herein made for so exciting the couch roll drive motor M1 that it has a substantially constant torque output during normal conditions. Provision is also made for reducing the excitation of the couch roll drive motor M1 when the vacuum in the wire run drops. This is highly advantageous in that it prevents the couch roll drive motor M1 from attempt- '14 ing to run away with the load and also prevents slippage of the couch roll with respect to the wire.

As shown in Figure 5, the field 121 of the couch roll generator G1 is connected to the output armature brushes of a generator 213. The generator 213 has two control .fields 214 and 215 and is preferably an amplidyne having one pair of opposite armature brushes connected together and a compensating field 213a, as illustrated, so that a small change in the current through either field will instantaneously effect a relatively large change in output. The field 215 is connected to output terminals 216 and 217 of an electronic amplifier 218. The electronic amplifier 218 has input terminals 219 and 220 which are connected on either side of a resistor 221 in series with the couch roll motor M1. The electronic amplifier 218'may be of any desired type and may, for example, have a circuit similar to the circuit incorporating tubes and which control the excitation of the wire turning roll generator G2.

The electronic amplifier 218 is so connected that a small increase in the current through the motor M1 and resistor 221 and the corresponding change in voltage between the terminals 219 and 220 will instantaneously effect a relatively large reduction in the output voltage appearing between terminals 216 and 217 so that the excitation of the control field 215 will be reduced. Conversely, a decrease in the current through the motor M1 and the resistor 221 will effect a large increase in the excitation of the control field 215. With this circuit, the current through the couch roll drive motor M1 and the torque applied to the couch roll 13 will be maintained constant regardless of variations in the load on the couch roll 13 and the speed of the couch roll 13.

The control field 214 is connected to output terminals 223 and 224 of an electronic amplifier unit 225. The electronic amplifier unit 225 has a pair of input terminals 226 and 227 which are connected to the terminals 76 and 74, respectively, of the vacuum-controlled potentiometer device 71. As described above in connection with the preferred machine of Figures 1 through 4, the device 71 is connected through a line 79 to the vacuum or suction means 15 of the couch roll 13 and controls the position of a movable contact 75 in accordance with the vacuum in the couch roll. The terminals 73 and 74 of the device are connected to the positive bus 70 and the negative bus 68, respectively, so that the potential between the terminals 74 and 76 increases as the vacuum decreases and decreases as the vacuum increases.

The circuit of the electronic amplifier unit 225 is such that an increase in the potential of the terminal 226 with respect to the terminal 227 will result in a decreased output voltage appearing between the terminals 223 and 224. Conversely, a decrease in the potential of the terminal 226 with respect to the terminal 227 will.

result in an increased voltage output between the terminals 223 and 224. Accordingly, if the vacuum in the couch roll 13 should be reduced to a low value due to loss of the web from the wire, for example, the potential of the terminal 76 and the terminal 226 will be increased, the current through the field 214 will be decreased, the output of the generator 213 and the field excitation of the generator G1 will be decreased and the excitation of the motor M1 will be decreased so that it cannot run away with the load and so that slippage of the couch roll 13 with respect to the wire cannot occur.

Figure 6 illustrates another modification of the forming section drive in which the control of the excitation of the couch roll drive motor M1 and the wire turning roll drive motor M2 is the same as with the modification of Figure 5 as above described. In this modification, a vacuum line 228 is connected from the potentiometer device 71 to the vacuum header 12 for the evacuated boxes 11. Thus the position of the movable contact 75 of the potentiometer device 71 is controlled in accordance with the vacuum in the evacuated boxes 11.

This is highly advantageous in that it positively prevents the couch roll drive motor M1 from running away with the load. The drag on the wire 10 and the torque required to drive the wire are largely determined by the vacuum in the fiat boxes 11, the only other drag on the wire being the friction of the rolls about which the wire is entrained. With the modification of Figure 6, if the vacuum in the flat boxes 11 should drop for any reason, the excitation of the couch roll drive motor M1 will be limited through the action of the potentiometer device 71. This overcomes a disadvantage of the modification of Figure 5 in which the device 71 is controlled in accordance with the vacuum in the couch roll 13 and in which it would be possible for the vacuum in the flat boxes 11 to be lost without loss of vacuum in the couch roll 13, thus permitting the couch roll drive motor M1 to run away with the load. At the same time, the modification of Figure 6 acts to reduce the excitation of the couch roll drive motor M1 and prevent slippage of the wire with respect to the couch roll 13 in the event that the vacuum in both the couch roll 13 and the fiat boxes 11 is reduced to a low value due to loss of web from the wire.

To summarize, it is to be observed that this invention involves a paper making machine having a forming section comprising the wire 10, the couch roll 13 having a peripheral surface portion in driving engagement with the wire and the wire-turning roll 14 having a peripheral surface portion in driving engagement with the wire, the wire being maintained in frictional engagement with the peripheral surface portion of the wire-turning roll 14 solely through tension in the wire. The press-section comprises the looped pick-up felt 16 and a pick-up roll 17 in the loop of the felt. Manually operable means 2023 are connected to the pick-up roll 17 to adjustably move the same toward and away from the wire and thereby obtain either an open or a closed web draw between the wire and the pick-up felt. A first drive means is mechanically coupled to the forming section to drive the same, the first drive means more particularly comprising the motors M1 and M2, and second drive means are mechanically coupled to the press section, such drive means more particularly comprising the motors M3M7. A main power source is provided, such comprising the motive power source connected to the generators G1, G2, 101, etc. Coupling means or drive-transmitting means are provided between the power source and the drive means. Such coupling means are formed by the forming section excitation and control units and the press section excitation and control unit. In the case of the couch roll drive motor M1, the drive-transmitting or coupling means comprises, of course, the generator G1 and in the case of the wire-turning roll motor M2, the coupling or transmitting means comprises the generator G2 and associated circuitry.

The drive system of this invention further incorporates means associated with the coupling or drive-transmitting means for maintaining a certain speed ratio between the drive speed of the wire and the drive speed of the pickup felt. In the modification of Figure 1, such means are defined by the tachometers T1 and T2, and associated circuitry.

An important feature is in the use of the sensing means, such as the resistor 55 and associated circuitry to produce a signal proportional to the output of one of the drive means, and connection means such as the arrangement including 59, 60, 143-145, 154), etc., for connecting the sensing means to the drive-coupling or transmitting means to reduced the drive speed ratio as the load on one of the drive means increases. In addition, means such as the switch 151 are associated with the connection means-to selectively render the same operable for. closed web draw operation and inoperable for open web draw operation.

This, of course, forms a basic feature of the invention, as thoroughly described heretofore.

Another important feature is in the use of sensing means, such as the resistor 164 and associated circuitry to re ulate the transfer of power from one of the power transmitting means and produce a substantially constant torque output therefrom. This is particularly important in combination with a wire-turning roll in which the frictional engagement with the wire is determined solely by tension in the wire, in that it results in a distribution of tension in the wire, and reduces flexure thereof. It is also important in the combination in which a certain drive speed ratio is maintained between the speed of the pickup felt and the speed of the wire.

Still another important feature is in the combination of means, such as circuit 171, 172, 167, etc., to produce a signal proportional to the output of one of the drivetransrnitting means and coupling means such as amplidyne 166 connected to 165, to control the output of a second drive-transmitting means in proportion to the power output of the first, so as to maintain a proper load division therebetween. A still further feature is in the provision, in such a combination, of means associated with one of the drive-transmitting means to limit the power output thereof.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. In a paper making machine including a forming section and a press section, said forming section comprising a wire onto which stock is supplied to form a web, a couch roll having a peripheral surface portion in driving engagement with the wire and a wire-turning roll having a peripheral surface portion in driving engagement with the wire, said press section comprising a looped pick-up felt, a pick-up roll in the loop of said felt and manually operable means connected to said pick-up roll to adjustably move the same toward and away from the wire and selectively obtain either a closed or an open web draw between the wire and the pickup felt, first drive means mechanically coupled to said forming section to drive the same, second drive means mechanically coupled to said press section to drive said pick-up felt, a power source, a pair of coupling means coupling said power source to said first and second drive means, means associated with said coupling means for maintaining a certain speed ratio between the drive speed of said wire and the drive speed of said pick-up felt, sensing means associated with one of said first and second drive means to produce a signal proportional to the output thereof, connection means connecting said sensing means to one of said pair of coupling means to reduce said. certain drive speed ratio as the load on one of said drive means increases, and means associated with said connection means to selectively render the same operable for closed web draw operation and inoperable for opening web draw operation.

2. In a paper making machine including a forming section and a press section, said forming section comprising a wire onto which stock is supplied to form a web, a couch roll having a peripheral surface portion and driving engagement with the wire and a wire-turning roll having a peripheral surface portion in driving engagement with the wire, the wire being maintained in frictional engagement with said peripheral surface portion of said wire-turning roll solely through tension in the wire, said press section comprising a looped pick-up felt, and a pick-up roll in the loop of said felt, power supply means, a first drive element drivingly connected to said couch roll, a second drive element drivingly connected to said wire-turningroll, a third drive element arranged to impart drive to said'pick-up roll, first power transmitting means connected between said power supply means and said first drive element, second power transmitting means connected between said power supply means and said second drive element, third power transmitting means connected between said power supply means and said third drive element, a first sensor associated with one of said first and second drive -transmitting means to develop an output in response to the torque output therefrom, coupling means interconnecting the output of said first sensor and one of said drive-transmitting means to regulate the transfer of power from said one of said first and second power transmitting means and produce a substantially constant torque output therefrom, and a pair of means respectively associated with the other of said first and second power transmitting means and said third power transmitting means to obtain a certain drive speed ratio between the speed of the wire and the speed of the pick-up felt.

3. In a paper making machine including a forming section and a press section, said forming section comprising a wire onto which stock is supplied to form a web, a couch roll having a peripheral surface portion in driving engagement with the wire and a wire-turning roll having a peripheral surface portion in driving engagement with the wire, the wire being maintained in frictional engagement with the peripheral surface portion of said wireturning roll solely through tension in the wire, a first drive element drivingly connected to said couch roll, a second drive element drivingly connected to said wireturning roll, a power supply, first power transmitting means connected between said power supply and said first drive element, second power transmitting means connected between said power supply and said second drive element, output sensing means associated with one of said first and second drive-transmitting means to develop a signal proportional to the output thereof, and coupling means connecting said output sensor and the other of said drive-transmitting means to control the output thereof in proportion of the output of said one of said first and second drive-transmitting means.

4. In a paper making machine including a forming section and a press section, said forming section comprising a wire onto which stock is supplied to form a web, a couch roll having a peripheral surface portion in driving engagement with the wire and a wire-turning roll having a peripheral surface portion in driving engagement with the wire, the wire being maintained in frictional engagement with the peripheral surface por- 18 tion of said wire-turning roll solely through tension in the wire, a first drive element drivingly connected to said couch roll, a second drive element drivingly connected to said wire-turning roll, a power supply, first power transmitting means connected between said power supply and said first drive element, second power transmitting means connected between said power supply and said second drive element, output sensing means associated with one of said first and second drive-transmitting means to develop a signal portional to the output thereof, coupling means connecting said output sensor and the other of said drive-transmitting means to control the output thereof in proportion to the output of said one of said first and second drive-transmitting means, and means associated with said other of said drive-transmitting means to limit the power output thereof.

References Cited in the file of this patent 20 UNITED STATES PATENTS 1,786,755 James Dec. 30, 1930 1,846,770 Vogel Feb. 23, 1932 2,104,674 Roberts Jan. 4, 1938 2,204,426 Millspaugh June 11, 1940 2,356,567 Cockrell Aug. 22, 1.944 2,357,201 Hornbostel Aug. 29, 1944 2,411,162 King Nov. 19, 1946 2,415,350 Hornbostel Feb. 4, 1947 2,415,351 Hornbostel Feb. 4, 1947 2,443,352 Hornbostel June 15, 1948 2,445,416 Baker et a1 July 28, 1948 2,467,556 James et al Apr. 19, 1949 2,487,702 Goodwillie Nov. 8, 1949 2,498,234 Baker et a1. Feb. 21, 1950 FOREIGN PATENTS 592,476 Germany Feb. 9, 1934 OTHER REFERENCES Modern Pulp and Paper Making, by Witham, 2nd ed., folded multi-page diagram between pages 370 and 371 and pp. 37l-412 pub. by Reinhold Publishing Corp, New York (1942). (Copy in Div. 67.)

Shoults et al. Industrial Applications of Amplidyne Generators, General Electric Review, 119, published by General Electric Co., Schenectady, N. Y. (Copy in Sci. Lib.)

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