US2164600A - Hydraulic drive for winding apparatus - Google Patents

Description

July 4, 1939. R TYLER 2,164,600

HYDRAULIC DRIVE FOR WlNDING APPARATUS Filed Dec. 11, 1937 INVENTOR. H AN SI] M T YLER' i atented July 4, 1939 UNITED STATES HYDRAULIC DRIVE FOR WINDING APPARATUS Ransom Tyler, Greenfield, Wis., assignor to The Ollgear Company, Milwaukee, Wins a corporation of Wisconsin Application December 11,1937, Serial No. 179,301

12 Claims.

This invention relates to hydraulic drives for machines which operate upon web material and wind it into rolls.

An object of the invention is to provide a hydraulic drive which will enable a machine of this character to maintain a substantially uniform tension upon the web as it passes therethrough.

Another object is to provide a hydraulic drive which will rotate a winding shaft to cause web to be wound thereon and which will maintain a substantially uniform tension upon the web regardless of variations in the speed of the web.

Another object is to provide a drive which will rotate a shaft to cause web to be wound thereon under a substantially uniform tension and which will act as a brake to maintain a substantially uniform tension upon a web when being unwound from a shaft.

Another object is to provide a hydraulic drive which will enable a machine to unwind web from a parent roll and wind it into a semi-finished roll, then unwind it from the semi-finished roll and wind it into a finished roll, and maintain a substantially uniform tension upon the web during each winding and rewinding thereof.

Other objects and advantages will appear from the description hereinafter given of a hydraulic drive in which the invention is embodied.

According to the invention in one of its aspects, a shaft having a roll of web fixed thereon and varying in diameter as the web is wound thereon or unwound therefrom is connected to a hydrodynamic machine which will be driven by the shaft and function as a pump if web is unwound from the roll and will function as a motor and drive the shaft to cause web to be wound thereon if the machine is supplied with liquid from a constant pressure source, means are provided for resisting the discharge of liquid from the machine, and the resistance to the discharge of liquid is varied in response to variations in the diameter of the roll.

According to the invention in another aspect, a hydraulic motor is supplied with motive liquid at a constant pressure and rotates a shaft to cause web to be wound thereon into a roll, the discharge of liquid from the motor is resisted by means the resistance of which is decreased in response to the roll of web increasing in diameter, the web is unwound from a parent roll fixed upon a shaft which is connected to and drives a pump as the web is unwound from the parent roll, and the discharge of liquid from the pump is resisted by means the resistance of which is decreased in response to the parent roll decreasin in diameter.

The invention is exemplified by the drive shown schematically in the single figure of the accompanying drawing.

For the purpose of illustration, the invention has been shown as being embodied in a drive for an apparatus for applying a coating of rubber to each side of a web but the invention is not limited to this particular use nor to the particular 10 arrangement shown.

Since the apparatus forms no part of the present invention, it has not been illustrated and will not be described in detail. It is deemed sufllcient to state that it includes an unwind shaft I upon which a parent roll 2 of fabric web 3 is fixed to rotate therewith, a unit which applies coating to web 3 and which has been represented by three rollers 4, 5 and 6, an intermediate shaft 1 upon which web 3 is wound into a semi-finished roll 8 Q during one part of the coating process and from which web 3 is unwound during another part of the coating process, a rewind shaft 9 upon which web 3 is wound into a finished roll I0, and suitable guide rollers such as rollers ll, l2 and I3 2 for guiding the web from one part of the machine to another part thereof.

Shaft I has been shown as being connected by a drive IE to the shaft I! of a pump l8 which is driven by shaft I when web 3 is unwound from roll I.

Shaft I has been shown as being connected by a drive 19 to the shaft 20 of a hydrodynamic machine 2| which is driven by shaft 1 and functions as a pump when web 3 is unwound from roll 8 and which functions as a motor and drives shaft 1 when web is to be wound thereon.

Shaft 3 has been shown as being connected by a drive 22 to the shaft 23 of a hydraulic motor 24 which drives shaft 9 when web is to be wound thereon.

For the purpose of illustration, drives l6, l9 and 22 have been shown as being of the belt and pulley type but in practice each of shafts l, 'l and 9 is connected to the shaft of its associated pump or motor by a positive drive such as by being connected directly thereto or through suitable gearing.

Liquid for energizing hydrodynamic machine 2| when it is to function as a motor and for energizing motor 24 is supplied by a pump 25 which is driven by an electric motor 26 and arranged therewith upon the top of a reservoir 21 containing a supply of liquid such as oil.

Pump 25 is of the constant pressure type. That is, it will deliver liquid at its maximum volumetric rate until the pressure of the liquid delivered by it reaches a predetermined maximum and then its displacement will be automatically reduced until the pump is delivering liquid at a rate just sufficient to maintain the maximum pressure constant. A pump of this type is shown in Patent 2,080,810.

Operation of hydrodynamic machine 2| is controlled by a valve having two spaced apart heads or pistons formed thereon and closely fitted in a valve casing 3|, and operation of motor 24 is controlled by a valve 32 having two spaced apart heads or pistons formed thereon and closely fitted in a valve casing 33.

The delivery of liquid from pump 25 to hydrodynamic machine 2| and to motor 24 is controlled in the first instance by a start and stop valve 34 having two spaced apart heads or pistons formed. thereon and closely fitted in a valve casing 35.

In order to prevent entrapped liquid or air from impeding the operation of the valves, valve casings 3| and 35 have each end thereof connected to a drain channel 36 which discharges into reservoir 21, and both ends of valve casing 33 are connected to a drain channel 3'! which discharges into reservoir 21 through channels not shown.

Pump 25 has its outlet connected by a channel 40 to valve casing 35 intermediate the ends thereof, and valve casing 35 is connected intermediate its ends by a channel 4| to valve casing 33 intermediate the ends thereof, the ends of channels 40 and 4| being spaced from each other so that, when valve 34 is in the position shown in full lines, liquid discharged by pump 25 may flow through channel 40 and valve casing 35 into channel 4| and, when valve 34 is shifted toward the right to the position shown in dotted lines, one of its pistons will block channel 40 and no liquid can be delivered to channel 4|.

Valve casing 3| is connected intermediate its ends to channel 4| by a channel 42 and to one port of hydrodynamic machine 2| by a channel 43 so that, when valve 30 is in the position shown in full lines, liquid may flow from channel 4| through channel 42, valve casing 3| and channel 43 to hydrodynamic machine 2| and cause it to function as a motor and drive shaft 1 and, when valve 30 is shifted toward the left to the position shown in dotted lines, one of its pistons will block channel 42 and no liquid can be delivered to machine 2|.

Valve casing 33 is connected intermediate its ends to the inletof motor 24 by a channel 44 having fitted therein a check valve 45 which permits liquid to flow freely from valve casing 33 to motor 24 but prevents it from flowing in the opposite direction. The end of channel 44 is spaced from the end of channel 4| so that, when valve 32 is in the position shown in full lines, one of its pistons will block channel 44 and no liquid can be delivered to motor 24 and, when valve 32 is shifted upward to the position shown in dotted lines, liquid may flow from channel 4| through valve casing 33 and channel 44 to motor 24 and cause it to drive shaft 9.

When motor 24 is operating, the discharge of liquid therefrom is resisted by a resistance valve 48 which has its inlet connected to the outlet of motor 24 by a channel 49 and its outlet connected to a return channel 50 having one branch thereof connected to the inlet of pump l8, another branch thereof connected to the intake of pump 25, and another branch thereof connected to the inlet of a check valve 5| which has its outlet connected by a channel 52 to one port of hyd dynamic machine 2| and prevents liquid from flowing therefrom directly into channel 50 but permits free flow in the opposite direction.

Since the torque of a hydraulic motor is proportional to the drop in pressure across the motor and since liquid is delivered to motor 24 at a constant pressure, the torque exerted by motor 24 will be proportional to the difference between the pressure created by pump 25 and the pressure required to open resistance valve 48. Therefore, since the torque required to rotate shaft 9 and to maintain a uniform tension upon web 3 as it is wound upon shaft 9 will progressively increase as roll It! increases in diameter, the resistance of valve 48 must be progressively decreased in response to roll it] increasing in diameter in order that motor 24 may maintain a uniform tension upon web 3.

As shown, an adjusting screw 55 has its head end in contact with the spring 56 of valve 48 and its threaded end fixed in an adjusted position to a lug 51 which is pivoted to a lever 58 intermediate the ends thereof.

Lever 58 is pivoted at its lower end upon a sta-.

tionary bracket 59 and connected at its upper end by a pair of links 60 to a slide block 6| which is fixed by a set screw 62 in adjusted position on a lever 63 intermediate the ends thereof.

Lever 63 is pivoted at its lower end upon a stationary bracket 64 and provided at its upper end with a roller 65 which is held in contact with roll Ill by a spring 66 connected to lever 58.

The arrangement is such that, as roll H] increases in diameter, roller 65 will be moved outward thereby and swing lever 63 upon bracket 64, and lever 63 through links 60 will swing lever 58 upon bracket 59 and cause adjusting screw 55 to decrease the tension of spring 56, thereby reducing the resistance of valve 48 with the result that the torque of motor 24 progressively increases as roll |0 progressively increases in diameter so that motor 24 is thus enabled to maintain a substantially constant tension upon web 3 as it is wound upon shaft 9.

By adjusting screw 55 relatively to lug 57, the tension of spring 56 may be adjusted and thereby regulate the pressure required to open valve 48 when roller 65 is in any given position and, by shifting block 6| along lever 63, regulation is obtained of the rate at which the resistance of valve 48 decreases relatively to the rate at which the diameter of roll It! increases.

When pump I8 is being driven due to web being unwound from parent roll 2, it will be supplied with liquid through channel 50 and discharge liquid through a channel 10, a resistance valve H and a channel 12 into return channel 50. Valve resists the discharge of liquid from pump I8 and thereby enables pump I8 to resist rotation of roll 2 so that tension is maintained upon the web as it is unwound from the parent roll.

Since the torque required to drive a pump is proportional to the pressure created by the pump, the torque required to drive pump |8 will be proportional to the pressure required to open resistance valve H, and since the torque required to maintain a given tension upon web 3 is proportional to the diameter of parent roll 2, it is apparent that the resistance of valve must be progressively decreased in response to roll 2 decreasing in diameter in order that pump I8 may maintain a uniform tension upon web 3.

The mechanism shown for adjusting resistance valve H is substantially the same as the mechanism shown for adjusting resistance valve 48 and previously described. Consequently, corresponding parts have been indicated by corresponding reference numerals with the exponent a added to the numerals applied to the several parts of the mechanism which adjusts valve 48, and a detailed description thereof will not be given.

It is deemed sufllcient to state herein that, as parent roll 2 decreases in diameter due to web 3 being unwound therefrom, roller 65 will move toward shaft I and swing lever 68 upon bracket 84, and lever 63 through links I58 will swing lever 58 upon bracket 58 and cause adjusting screw 55 to decrease the tension of spring 56!, thereby reducing the resistance of valve H with the result that the torque required to drive pump l8 will progressively decrease as roll 2 progressively decreases in diameter so that pump i8 is thus enabled to maintain a substantially uniform tension upon web 3 as it is unwound from roll 2.

Hydrodynamic machine 2|, when functioning as a motor, discharges through a resistance valve l5 which has its inlet connected to channel 52 by a channel it, its outlet connected to return channel 50 by a channel ll, and which is provided with an adjusting screw 18 for regulating the tension of its spring 18. When hydrodynamic machine 2| functions as a pump, it discharges through a resistance valve 80 which has its inlet connected by a channel 8| to valve casing 3| at a point spaced from channel 43, its outlet connected to return channel 50 by a channel 82, and which is provided with an adjusting screw 83 for regulating the. tension of its spring 84.

The arrangement is such that, when valve 30 is in the position shown in full lines, motive liquid may flow through valve casing 3| and channel 43 to machine 2| and cause it to drive shaft 1 and discharge through resistance valve and, when valve 38 is shifted toward the left to the position shown in dotted lines and machine 2| is being driven by web being unwound from shaft 1, channel 42 will be blocked so that motive liquid cannot be delivered to machine 2|, channel 43 will be open to channel 8| and machine 2| will draw liquid from return channel 50 through check valve 5| and channel 52 and discharge it through channel 43, valve casing 3|, channel 8|, resistance valve 80 and channel 82 into return channel 50.

In order that a substantially uniform tension may be maintained upon web 3 when it is being wound upon shaft 1, it is necessary that the resistance of valve 15 be decreased as roll 8 increases in diameter for the same reason that the resistance of valve 48 must be decreased as roll in increases in diameter and, in order that a substantially uniform tension may be maintained upon web 3 when it is being unwound from roll 8, it is necessary that the resistance of valve 80 must be decreased as roll 8 decreases in diameter for the same reason that the resistance of valve 1| must be decreased as roll 2 decreases in diameter.

Since the mechanism for adjusting resistance valves 15 and 80 may be substantially the same as the mechanism shown for adjusting resistance valve 48 and previously described, corresponding parts have been indicated by corresponding reference numerals with the exponent b added to the numerals applied to the several parts of the mechanism which adjusts valves 15 and 80 and a detailed description thereof will not be given. The only essential difference between the two mechanisms is that lug 51 is larger than lug 51 and has both of adjusting screws 18 and 83 connected thereto.

The arrangement is such that, when machine 2| is functioning as a motor and driving shaft 1 to cause web 8 to be wound thereon, the increase in the diameter of roll 8 will cause roller 85 to move toward the left, and lever 63 will swing the upper end of lever 58 toward the left and cause adjusting screw I8 to decrease the tension of spring 19, thereby reducing the resistance of valve 15 with the result that the torque of machine 2| progressively increases as roll 8 increases in diameter so that machine 2| is thus enabled to maintain a substantially uniform tension upon web 3 as it is wound upon shaft 1.

Conversely, when machine 2| is being driven and functioning as a pump due to web 3 being unwound from roll 8, the decrease in the diameter of roll 8 will permit roller 65* to move toward the right, and lever 63 will swing the upper end of lever 58 toward the right and cause adjusting screw 83 to decrease the tension of spring 84, thereby reducing the resistance of valve 88 with the result that the torque required to drive machine 2| will progressively decrease as roll 8 decreases in diameter so that machine 2! is thus enabled to maintain a substantially uniform tension upon web 3 as it is unwound from shaft 1.

Operation Assuming that a parent roll 2 of web 3 is fixed upon shaft I, that web 3-has been passed around roller 6 and attached to shaft 1 as shown in full lines, that the several parts of the drive are in the positions shown in full lines and that pump is running, the drive will function as follows:

Pump 25 will deliver liquid at a constant pressure through channel 40, valve casing 35, channels 4| and 42, valve casing 3| and channel 43 to hydrodynamic machine 2| and cause it to drive shaft 1 which will wind web 3 thereon into a roll 8.

The liquid discharged by machine 2| will flow through channels 52 and I8, resistance valve 15 and channel 'l'l into return channel 50, the difference between the pressure created by pump 25 and the pressure required to open valve 15 determining the torque of machine 2| and the tension maintained by machine 2| upon web 3, the resistance of valve 15 being progressively reduced to keep the tension on web 3 substantially uniform as previously explained.

Web 3 is unwound from roll 2 as it is wound up on shaft 1 so that shaft is rotated and pump I8 is driven thereby. Pump I8 will discharge through resistance valve H which will enable pump l8 to maintain tension upon web 3 and which will have its resistance progressively reduced to keep the tension on web 3 substantially uniform as previously explained.

As web 3 passes through the coating unit, rubher is fed between rollers 4 and 5, carried around upon roller 5 and pressed thereby into the upper face of web 3 so that the web has one face thereof coated as it is wound into a roll 8 upon shaft 1.

After roll 8 has been completed, valve 34 may be shifted to the position shown in dotted lines to block channel and thereby stop machine 2|. Web 3 may then be led from roll 8 through the coating unit, around rollers l2 and 3 and attached to shaft 9 so that the web may be unwound from roll 8 and wound into a roll l0 upon shaft 9 as indicated by dotted lines. As the web passes between rollers 5 and 5, its uncoated face is presented to roller 5 which presses rubber thereon so that the web is coated upon both of its faces when it is wound into a roll I0.

After web 3 has been attached to shaft 9, valves 30 and 32 are shifted to the positions shown in dotted lines and valve 34 is shifted to the position shown in full lines. Pump 25 will then deliver liquid at a constant pressure through channel 40, valve casing 35, channel 4|, valve casing 33 and channel 44 to 'motor 24 and cause it to drive shaft 9 which will wind web 3 thereon into a roll in.

The liquid discharged by motor 24 will flow through channel 49 and resistance valve 48 into return channel 50, the diiferenece between the pressure created by pump 25 and the pressure required to open valve 48 determining the torque of motor 24 and the tension maintained by motor 24 upon web 3. The resistance of valve 48 is progressively reduced to keep the tension on web 3 substantially uniform as previously explained.

Web 3 is unwound from roll 8 as it is wound up on shaft 9 so that shaft 1 is rotated and machine 2! is driven thereby and functions as a pump. Machine 2| will discharge through channel 43, valve casing 3|, channel 8|, resistance valve 80 and channel 82 into return channel 50. Resistance valve 80 will enable machine 2| to maintain tension upon web 3, and the resistance of valve 80 will be progressively reduced as the diameter of roll 8 decreases to thereby maintain the tension upon web 3 substantially uniform as previously explained.

The hydraulic drive described herein may be modified in various ways and adapted to various uses without departing from the scope of the invention as hereafter claimed.

The invention is hereby claimed as follows:

1. The combination, with a shaft and a roll of web material fixed upon said shaft and varying in diameter as said web is wound thereon or unwound therefrom, of a hydrodynamic machine having a rotatable member connected to said shaft to rotate therewith, said hydrodynamic machine having two ports and being adapted to rotate said member and discharge liquid from one of said ports upon motive liquid being supplied thereto through the other port and to draw liquid through one of said ports and discharge it through the other port upon said member being rotated, means for supplying liquid at a substantially constant pressure to said machine to enable it to drive said shaft, a resistance valve for resisting the discharge of liquid from said machine and having a spring urging it toward closed position, and means responsive to variations in the diameter of said roll for varying the tension of said spring.

2. The combination, with a shaft and a roll of web material fixed upon said shaft and varying in diameter as said web is wound thereon or unwound therefrom, of a hydrodynamic machine having a rotatable member connected to said shaft to rotate therewith, said hydrodynamic machine having two ports and being adapted to rotate said member and discharge liquid from one of said ports upon motive liquid being supplied thereto through the other port and to draw liquid through one of said ports and discharge it through the other port upon said member being rotated, means for supplying liquid at a substantially constant pressure to said machine to enable it to drive said shaft, a resistance valve for resisting the discharge of liquid from said machine and having a spring urging it toward closed position, means for varying the tension of said spring, and a roller engaging the periphery of said roll and connected to said means for operating the same in response to variations in the diameter of said roll.

3. The combination, with a shaft, means for delivering a substantially continuous web to said shaft to be wound thereon into a roll and means for unwinding said web from said roll, of a hydrodynamic machine connected to said'shaft and adapted to be driven thereby and function as a pump during the unwinding of web from said roll, a first resistance valve for resisting the discharge of liquid from said machine when functioning as a pump to enable said machine to act as a brake upon said shaft, a source for supplying motive liquid at a substantially constant pressure to said machine to cause it to function as a motor and drive said shaft, a second resistance valve for resisting the discharge of liquid from said machine when functioning as a motor, means for directing liquid from said source to said machine and for directing the discharge from said machine through said second resistance valve, and means responsive to variations in the diameter of said roll for varying the resistance of said resistance valves.

4. The combination, with a shaft, means for delivering a substantially continuous web to said shaft to be wound thereon into a roll and means for unwinding said web from said roll, of a hydrodynamic machine connected to said shaft and adapted to be driven thereby and function as a pump during the unwinding of web from said roll, a first resistance valve for resisting the discharge of liquid from said machine when functioning as a pump to enable said machine to act as a brake upon said shaft, a source for supplying motive liquid at a substantially constant pressure to said machine to cause it to function as a motor and drive said shaft, a second resistance valve for resisting the discharge of liquid from said machine when functioning as a motor, means for directing liquid from said source to said machine and for directing the discharge from said machine through said second resistance valve, a lever for varying the resistances of both of said valves, and means responsive to variations in the diameter of said roll for operating said lever.

5. The combination, with a shaft, means for delivering a substantially continuous web to said shaft to be wound thereon into a roll and means for unwinding said web from said roll, of a hydrodynamic machine connected to said shaft and adapted to be driven thereby and function as a pump during the unwinding of web from said roll, a first resistance valve for resisting the discharge of liquid from said machine when functioning as a pump to enable said machine to act as a brake upon said shaft, a source for supplying motive liquid at a substantially constant pressure to said machine to cause it to function as a motor and drive said shaft, a second resistance valve for resisting the discharge of liquid from said machine when functioning as a motor, means for directing liquid from said source to said machine and for directing the discharge from said machine through said second resistance valve, and means responsive to variations in the diameter of said roll for decreasing the resistance of said first resistance valve as said roll decreases in diameter and for decreasing the 65 periphery of said parent roll, means for transresistance of said second resistance valve as said roll increases in diameter.

6. The combination, with a shaft for winding a substantially continuous web thereon into a roll and means for resisting the winding of said web upon said shaft, of a hydraulic motor for driving said shaft, means for supplying motive liquid to said motor at a substantially constant pressure to energize the same, a resistance valve connected to the outlet of said motor and having a valve member urged by a spring in a direction to resist the discharge of liquid from said motor, and means responsive to said roll increasing in diameter for reducing the tension of said spring in proportion to the increase in roll diameter.

'7. The combination, with a shaft for winding a substantially continuous web thereon into a roll and means for resisting the Winding of said web upon said shaft, of a hydraulic motor for driving said shaft, means for supplying motive liquid to said motor at a substantially constant pressure to energize the same, a resistance valve connected to the outlet of said motor and having a valve member urged by a spring in a direction to resist the discharge of liquid from said motor, a lever for adjusting the tension of said spring, a roller contacting the periphery of said roll, and means for transmitting motion from said roller to said lever to thereby adjust the tension of said spring in proportion to variations in the diameter of said roll.

8. In a machine having an unwind shaft for carrying a parent roll of web and a winding shaft for winding said web into a new roll, the combination of a pump connected to said unwind shaft to be driven thereby as said web is unwound from said parent roll, a resistance valve for resisting the discharge of liquid from said pump, means for reducing the resistance of said valve in response to said parent roll decreasing in diameter, a hydraulic motor for driving said winding shaft, means for supplying motive liquid at a substantially constant pressure to said motor to energize it, a second resistance valve for resisting the discharge of liquid from said motor, and means for reducing the resistance of said second valve in response to said new roll increasing in diameter.

9. In a machine having an unwind shaft for carrying a parent roll of web and a winding shaft for winding said web into a new roll, the combination of a pump connected to said unwind shaft to be driven therby as said web is unwound from said parent roll, a resistance valve for resisting the discharge of liquid from said pump, a lever for adjusting said valve, a roller contacting the mitting motion from said roller to said lever to thereby effect a progressive reduction in the resistance of said valve as the diameter of said parent roll decreases, a hydraulic motor for driving said winding shaft, means for supplying motive liquid at a substantially constant pressure to said motor to energize it, a second resistance valve for resisting the discharge of liquid from said motor, a second lever for adjusting said second valve, :3. second roller contacting the periphery of said new roll, means for transmitting motion from said second roller to said second lever to thereby effect a progressive reduction in the resistance of said second valve as the diameter of said new roll increases.

10. In an apparatus for operating upon web material and having a first shaft for carrying a parent roll from which said web is to be unwound, a second shaft for winding said web thereon into a semi-finished roll and from which said web is to be unwound, and a third shaft for winding said web thereon into a finished roll, the combination of a pump connected to said first shaft to be driven thereby as said web is unwound from said parent roll, means for resisting the discharge of liquid from said pump to cause said pump to resist the unwinding of said web, means for reducing the resistance of said means in response to said parent roll decreasing in diameter, a hydrodynamic machine connected to said second shaft to function as a motor to drive said second shaft or as a pump to resist rotation thereof, means for supplying motive liquid at a substantially constant pressure to said machine to cause it to function as a motor and drive said second shaft and thereby cause said web to be wound thereon into a semi-finished roll, means for resisting the discharge of liquid from said machine while functioning as a motor, means for reducing the resistance of said last named means in response to said semi-finished roll increasing in diameter, a hydraulic motor for driving said third. shaft to cause said web to be wound thereon into a finished roll, said web being unwound from said semi-finished roll as it is wound 'into said finished roll and said machine being driven and caused to function as a pump by the unwinding of said web, means for resisting the discharge of liquid from said machine while functioning as a pump to cause said machine to resist the unwinding of Web from said semi-finished roll, means for reducing the resistance of said last named means in response to said semifinished roll decreasing in diameter, means for supplying motive liquid at a substantially constant pressure to said motor to energize it, means for resisting the discharge of liquid from said motor, and means for reducing the resistance of said last named means in response to said finished roll increasing in diameter.

11. In an apparatus for operating upon web material and having a first shaft for carrying a parent roll from which said web is to be unwound, a second shaft for winding said web thereon into a semi-finished roll and from which said web is to be unwound, and a third shaft for winding said web thereon into a finished roll, the combination of a pump connected to said first shaft to be driven thereby as said web is unwound from said parent roll, a resistance valve connected to the outlet of said pump to resist the discharge of liquid therefrom and thereby cause said pump to resist the unwinding of said web, means responsive to said parent roll decreasing in diameter for adjusting said valve to reduce the resistance thereof, a hydrodynamic machine connected to said second shaft to function as a motor to drive said second shaft or as a pump to resist rotation thereof, means for supplying motive liquid at a substantially constant pressure to said machine to cause it to function as a motor and drive said second shaft and thereby cause said web to be wound thereon into a semi-finished roll, a second resistance valve for resisting the discharge of liquid from said machine while functioning as a motor, means responsive to said semi-finished roll increasing in diameter for adjusting said second valve to reduce the resistance thereof, a hydraulic motor for driving said third shaft to cause said web to be wound thereon into a finished roll, said web being unwound from said semi-finished roll as it is wound into said finished roll and said machine being driven and caused to function as a pump by the unwinding of said web, a third resistance valve for resisting the discharge of liquid from said machine while functioning as a pump to cause said machine to resist the unwinding of web from said semi-finished roll, means responsive to said semi-finished roll decreasing in diameter for adjusting said third valve to reduce the resistance thereof, means for supplying motive liquid at a substantially constant pressure to said motor to energize it, a fourth resistance valve connected to the outlet of said motor to resist the discharge of liquid therefrom, and means responsive to said finished roll increasing in diameter for adjusting said fourth valve to reduce the resistance thereof.

12. In an apparatus for operating upon web material and having a first shaft for carrying a parent roll from which said web is to be unwound, a second shaft for winding said web thereon into a semi-finished roll and from which said web is to be unwound, and a third shaft for winding said web thereon into a finished roll, the combination of a pump connected to said first shaft to be driven thereby as said web is unwound from said parent roll, a resistance valve connected to the outlet of said pump to resist the discharge of liquid therefrom and thereby cause said pump to resist the unwinding of said web, means responsive to said parent roll decreasing in diameter for adjusting said valve to reduce the resistance thereof, a hydrodynamic machine connected to said second shaft to function as a motor to drive said second shaft or as a pump to resist rotation thereof, a constant pressure pump for supplying liquid to said machine to cause it to function as a motor and drive said second shaft and thereby cause said web to be wound thereon into a semi-finished roll, a second resistance valve for resisting the discharge of liquid by said machine while iunctioning as a motor, means responsive to said semi-finished roll increasing in diameter for adjusting said second valve to reduce the resistance thereof, a hydraulic motor energized by liquid supplied by said constant pressure pump for driving said third shaft to cause said web to be wound thereon into a finished roll, said web being unwound from said semi-finished roll as it is wound into said finished roll and said machine being driven and caused to function as a pump by the unwinding of said web, a third resistance valve for resisting the discharge of liquid from said machine while functioning as a pump to cause said machine to resist the unwinding of Web from said semi-finished roll, means responsive to said semi-finished roll decreasing in diameter for adjusting said third valve to reduce the resistance thereof, a fourth resistance valve connected to the outlet of said motor to resist the discharge of liquid therefrom, means responsive to said finished roll increasing in diameter for adjusting said fourth valve to reduce the resistance thereof, valve means for controlling the delivery of liquid to said motor, and valve means operable to either direct liquid from said pump to said machine or to block the delivery of said liquid and direct the liquid discharged by said machine through said third resistance valve.

RANSOM TYLER.

Gil

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