US2162954A - Conveying apparatus - Google Patents

Description

kJune 20, 1939. H. s. I ENHART CONVEYING APPARATUS Filed July s1, 1936 :s sheets-sheet 1 INVENTOR H. SCLENHART BY@ 'dh/l5 1m/w V240@ s shets-sheet s Filed July 31, 1936 INVENTOR H. S. LENHART B [uuml 2 E. E YN Patented June 20, 1939 CONVEYING APPARATUS v Herbert S. Lenhart, Allentown, Pa., assigner to Fuller Company, Catasauqua, Pa., a corporation of Delaware Application July 31, 1936, Serial No. 93,555 9 claims. (c1. iso-17)"V This invention lrelates to conveying apparatus for dry pulverulent materials and more particularly to a portable conveyor or pump for unloading materials from'box-cars vand barges, and yfor reclaiming materials from the floors of Warehouses. The apparatus is especially intended to handle Portland cement, but may also be employed as a conveyor of pulverized limestone, lime, soda ash and other materials having similar physical characteristics. The pump is used in conjunction with the usual pipe-line system, the

- sired radius of movement.

The apparatus of the invention constitutes an improvement of that of Morrow Patent No. 1,890,298, and to a lesser extent, the patent referred to therein. The improved apparatus offers a wider field of utility; greater material handling capacity, the convenience, flexibility and `safety of operation by remote control; simplified mechanical construction, and decreased liability to accidental stoppages.

'I'he operation of the Morrow apparatus is wellknown in this art particularly through its use in handling cement during theconstruction of concrete structures. 'I'he cement is fed tothe barrel ofv the pump by a slowly rotating, perforated disc, the disc serving also to break down the compacted cement and to recover it over a relatively wide area. cement to pass through the disc, so that the disc will be maintained substantially parallel to the floor. A rapidly rotati *g impeller screw, lled to its maximum capacityggy the feed disc, advances the cement through the barrel, the cement being compacted as it is advanced by the effect of screw flights of decreasing pitch, to form a seal to resist a backward ow of air along the screw shaft. The seal density is usually augmented by a space between the terminal flight' of the screw and the orifices or air-ring, through which compressed air is admitted to the barrel.

length of this space is variable, usually by making the screw shaft axially adjustable, The shaft is directly driven by a motor, the rotor of which is secured to a bushingthrough which the shaft paSSeS.

Beyond the air ring,.the barrelopens into an elbow, which by-passes the screw shaft and motor, the elbow leading to the transport -pipe line. The pipe line comprises an initial section,

at least, of reinforced rubber hose, of sufficient length to permit the desired radius of movement of the pump, the remainder of the system being ordinarily black steel pipe,

The apparatus is supported for movement upon two wheels far enough 'in the rear of the center of balance of the pump, to overcome the drag of the hose and to maintain the apparatus tilted 'forwardly to rest upon an extension o f the feeder The perforations permit the as Well as the machine.

The

shaft below the disc. The wheels are driven through power take-off and speed-reductionv gearing, driven` by the screw shaft, the'wheels being arranged to be driven independently in either direction through separate pairs of clutches, one forward and one reverse, of the band type. Power is transmitted to the feed disc through a portion of the same gear train and additionalshafting and speed-reduction mechanism. The operator controls the movement of the apparatus by the manipulation .of t

levers which cause the clutches to be engaged.

This arrangement limits the capacity of the pump to handle materials, thel distance over which they may be conveyed, or both, as the power to move the pump and to drive the feed disc is also derived from the screw shaft motor. The limited motor power remaining available for pumping is further considerably decreased by the power transmission losses of the complicated system of gearing andclutches. Overloading is cumulative. When the cement is densely compacted, and slides descend upon the feed disc and overload both the latter and the screw, the operator rst attempts to withdraw the pump, which involves a further overload to an already overloaded motor, thereby increasing the possibility of stalling the apparatus, with the nal result that the operator must remove the cement before the machine can again be started.

Pumps of this type could not be used safely to recover cement fr om cement mill warehouses for fear that slides, occurring as the deeply piled cement is undermined, would bury the operator A further disadvantage exists in the fact that the pump cannot be moved from one location to another, without rotating the screw shaft. This frequently causes some of the residue of cement remaining in the barrel to enter and accumulate in some of the orices ofthe air ring, during movement of the pump, as the air supply should be shut off when the machine is not actually pumping to avoid a dust nuisance. The reduction in air flow then makes `subsequent operation erratic, due to in-v complete aeration. v

These and other disadvantages are overcome vin the present apparatus, principally because available motor power with respect both to ,vol/e of material substantially at a constant maximum v the pump will function eillciently even though it AVance into the stored material to maintain it under full load; to permit him to leave the pump while it is in operation so that -he may sweep or otherwise clean the floor of the residue of material; to permit the operator to control the pump from a safe distance, when recovering cement' from piles in a storage warehouse, and to prevent damage to the apparatus due to careless operation. A

kIn general, the new apparatus comprises a pumping assembly, substantially similar but considerably simpler than that of the Morrow patent. The feed disc is driven by a vseparate motor 'through speed-reduction mechanism, the operation of the motor being controlled within a predetermined rangevof loading of the screw motor, as more particularly described and claimed in my Patent No. 2,141,920.

The supporting wheels are preferably equipped with pneumatic tires to obtain better traction and are independently driven by separate elec- `tric motors and speed-reduction mechanisms, each wheel and its driving mechanism forming an assembly, a part of each assembly being enclosed in a gear case, the vgear cases forming integral parts of a yoke which supports the pump and is secured to the forward end-bell of the screw motor, and is preferably separable there# from. 'I'hese motors are ,provided with separatev circuits so that they may be driven to move the pump in 'any direction without starting the screw and feeder motors.

.The discharge elbow opens into a conduit passing centrally between t the wheel driving motors,

the end of the conduit being supported upon the rear end-bell of thescrew shaft motor, to elevate the hose and centralize and decrease its dragging effect.

All of the n iotor startersare preferably secured to a panel in a dust-proof casing which may be located at any convenient point, the power circuits'to the pump preferably being included -in a single cable paralleling and secured to the transport hose. Each of the whel vdriving motors is provided with a reversing starter, whereby the motors may be independently driven in either l direction, either together to cause the pump to advance or withdraw, or'V oppositely to cause the pump to turn on a substantially fixed pivot.

'r'hc actuating circuits for the starters for tric screw and wheel motors preferably form a cable leading from the casing,-the cable terminating in be used to actuate the wheel motor starters, but,

I prefer to employ enclosed switches of the mercury type, which are -closed in pairs or singly by tilting the handle in the direction in which the operator desires the machine to move. Bytilting the handle forwardly or backwardly, while the pushbutton switch abovereferred to is held in closed position, the pump will immediately move in either of these directions. By4 tilting the handle to one side or the other, the wheels will be rotated in opposite directions. The operator may move one wheel only, to swing the feed disc over a wider arc bytilting the handle to any one of the four angles mid-way between the positions described. When the pushbutton switch is in open position the wheel motor driving circuits cannot be closed accidentally and the operator may leave the switch assembly at any convenient place without stopping the operation of the pump. As movements of the switch handle are instinctive, an unskilled operator can employ th'e pump to its fullest efficiency Without confusion.

Compressed air is supplied through the usual flexible hose, paralleling and usually secured to vthe transport hose, to a connection to the air ring. A pressure actuated switch, of the conventional diaphragm type, may be conveniently supplied from this connection, the switch being connected in the screw motor starter circuit, so that the operator cannot start the pump before turning on the air supply,` the ,switch also serv-l ing to stop the pump and the feeder automatically if the air pressure falls below a ,predeter-l Fig. 3 is a plan view on a slightly reducedl scale; Fig. 4 is a detail, in partial vertical'section, of

the right-wheel driving assembly, on line 4-4 of Fig. 3;

Fig. 5 is a sectional detail, in plan, on line 5-:5`of Fig. 4;

' Fig. 6 is a schematic-wiring diagram of the power and control circuits, and A Fig. 7 is a side elevation of the handle enclosing the control switch assembly.

Referring to the drawings, and iirst to Figs. 1, 2 and 3, the apparatus will 4be seen to consist of a. pump casing or barrel I,provided with a flange 2 at'its inlet, to'which a similar flange 3 of the hood 4 is secured, the latter being open .at the bottom and flared outwardly to span one side of a feed disc 5, as shown in detail in Fig. 2. The

feed disc is approximately parallel with the floor, indicated by the line 6; upon which the material to beconveyed -is stored, but is tilted forward slightly to leave a minimum residue of material on the iioor. 'I'he hood l, is preferably formed of two sections, suitably flanged as at `1, and to which is secured a support 8, for the feed ldisc driving assembly which includes a motor M2,

'prefcramy cf the totauy enclosed, ban bearing,

squirrel cage, induction, elevator type. 'y This motor may 'have a speed of i125 R. P. M. arid drives the feed disc 5 throughl the shaft 9 and a built-in speed reducer III, preferably of the double parallel, geared head type, having atotal reduction ratio of 33.5:1, to drive tlf shaft 9 at a speed of 33.6 R. P. M., the shaft 9 being secured'to'the disc 5 by suitable flanges secured by rivets as in` dicated at il, the lower flange supporting the disc 5 out of actual contact with the floor. Contact with the walls of a car or other enclosure is prevented by means 'of rod I2 which may conveniently be secured to the support 8, the rod also 'is arranged concentrically within the barrel, in

the usual manner, with preferably at least one complete flight section within the hood 4, the leading edge of the flight being thus arranged to receive the maximum load carried by the feed disc 5. The pitch of the screw flights decreases, in the usual wam-toward the terminal flight, and the latter is spaced from the point of air admission,

yindicated generally as the air-ring I6, the barrel rbeing flanged and secured to the air-ring in the usual manner. Compressed air for rendering the material fluent inay be injected through the air-ring from any suitable source of supply, represented by the three-way cock I1 to which the usual flexible hose is secured, the cut-off cock I3 and the pipe-line I9, the cock I8 serving as an orifice plate of variable size to control the volume flow of air.

Secured to the barrel I beyond the air-ring I6, is an off-set discharge elbow 20 suitably flanged at 2|, and connected to a portion of the conduit 22 arranged centrally ofthe apparatus and forming an extension of the elbow, the conduit being supported by the rear end-bell 23 of the screw shaft driving motor MI, as indicated at 24. A non-return valve 25, of the gravity type, vis secured to the conduit beyond the support 24, the valve including a flap-valve 26, carried by a cra-nk 21, the crankbeing secured to a rod terminating in a crank 28, shown in Fig. 3. This valve is lifted from its seat by the flow of material, and closes when the flow stops. If the pump is to be stopped for a considerable time, sufficient to permit the air to escape from the aerated material, the operator opens the cock I1 to cause air at the full available volume to flow into the valve and system to move the material and clear the pipe-line while the material is still `tegral part thereof, the housing enclosing an oil seal 3| preferably of the double fixed and rotating ring type, the rotating rings being longitudinally movable on a 'short bushing 32 surrounding the shaft, so that the seal assembly, including the bushing 32, can be removed as a unit, after the shaft I4 has been withdrawn, through a port 33 in the side of the housing, shown in Fig. 3. 'I'he housing is chambered at 34 and supplied with air through suitable tubing from lthe connection I9, to provide the usual counter-current to prevent dust from moving rearwardly along the shaft, the oil seal 3l forming a dead-end. The housing 29 is secured to the forward end-bell 35 of the motor MI, the shaft passing through a bushing 36 to which the rotor of the motor MI is keyed, in the usual manner. The bushing 36 is supported for rotation in a radial and thrust bearing 31- arranged in a chamber in the forward end-bell 35 .and a radial bearing 38, similarly arranged in the rear end-bell 23. Beyond the bearing 38, the

shaft I4 is secured to the bushing by a key-ring standard commercial design.

- M3 and M4 are 2 horsepower, 1125 R. P. M., totalelevator type, 440 volt, 60 cycle, 3 phase.

modifythe seal distance between the terminal flight and the air-ring I6. The inner race of bearing 38 is held in place by a spacer 4I abutting a shoulder on key-ring 39. As the normal thrust of the material advanced by the screw maintains the shaft under tension, the inner race of bearing 31 is 4engaged by a shoulder formed on the bushing, the race being restrained from forward movement by a lock-washer and nut 43.

As will be seen in Fig. 3, the driving assemblies for the left wheel LW and the right wheel RW are similar and the driving motors M3 and` M4 are identical and only one assembly will be described in detail. Referring to Fig. 4, the motor M3 is provided with a geared head 44 including the pinion 45 and gear 46,` the latter being suitably keyed to the worm shaft 4l', theshaft being supported in suitable anti-friction bearings.

.Shaft 41 drives the worm 48 which engages a worm gear 49, the gear being keyed as at 50 to the axle 5I. The geared head 44 is secured to an upper ange of a gear case 52,-the gear case being formed as an integral part of a yoke 53 (Fig. 1), having an upper web 54 and a lower web 55, the yoke having a central, circular opening surrounding the'forward section of end-bell 35, and being secured thereto by cap-screws 56, as shown in Fig. 5. The yoke 53 is also provided with an angular boss 51 (Fig. 5) to which a brace 58 may be secured by a cap-screw 59, the other end .of the brace being secured to a similar boss 60, shown in Fig. 3 at the. side of the elbow 20 near the air-ring I6.

The axle 5I is semi-oating, -and its inner end is supported for rotation in a radial bearing 6I, the latter being secured bythe usual lockwasher and nut and separated from' the worm gear 49 by the spacer 62. 'I'he gear case 52 is enclosed by the cover 63, the latter being chambered to receive a radial and thrust bearing 64, the inner race of which is secured to the axle 5I by the lockwasher and nut 65, the outer race of the bearing being held by the retainer 66. vBeyond the retainer, the shaft is surrounded by a bushing 61, which receives the wheelV hub 68, the latter carrying a disc wheel 69, which may be of the Ford truck type, the disc being secured by stud bolts 10. Cap screws 1I pass through a hub cap 12 and secure it to the hub 68.' The hub cap is keyed to the shaft at I3 and secured by the usual nut 14.1' The wheel 15 is preferably provided with a pneumatic tire 16 of the heavy duty, truck type in order to obtain sufficient traction when the pump is moved against the face of a pile of material when the floor has not been entirely cleaned.

'I'he power and control circluitsl for the four motors are illustrated schematically in Fig. 46.

For simpliciay, the motors are indicated as three-l wire machines, but it willbe realized that as pumps of this type are frequently moved from one installation to another in construction work,

nine-wire motors would actually be employed, so that they may be connected in accordance with the voltage characteristics of the current available. It will be assumed, for example, that the pump is of common size havingv screw flights of' 6" diameter, the screw shaft being driven by motor MI of 40` horsepower, 1125 R. P. M., 440 volt, 60 cycle, 3 phase squirrel cage, induction, vertical type, the rotor and starter frames being ly enclosed, ball bearing, squirrel cage, induction, The control circuit may be supplied with alternating 7o 'Ihe motors M2, y

current at volts, 60 cycle, for the sake of safety.

The 440 volt power lines for the four motors are represented by the@ nes LI, L2 and L3, the 110 volt lines supplyinglr e starter actuating circuits being represented by lines L4 and L5. A full voltage magnetic starter Sl controls the-operation of the screw shaft motor MI, the starter being provided withl usual contacts for ener. gizing motor circuits TI, T2 and T3. These circuits include two thermal overload relays indicated generally at R. Circuit TI includes an adjustable, instantaneous overload relay RI, of-the type actuated by a solenoid and released to closethe contacts by gravity, the relay having contacts Kl in the actuating coil circuit of starter S2 for motor M2. voltage, magnetic type and is provided with similar thermal overload relaysR2,in the circuit of the feeder motor M2, the circuits being represented by the lines T4 and T5 and common wire T2, the starter having only two contacts as the circuit through the common wire is closed by starter SI.

Starter S3 controlsthe right wheel motor -M3 and'may conveniently be a reversible fulll voltage, magnetic starter having two sections of three contacts each, for energizing the motor through the usual circuits T6, Tl and T8 and the thermal as follows:

Starter Si, for the screw shaft motor Ml, is actuated by a maintaining contact switch K2, the latter forming a part of a portable switch assembly, shown in Fig. 7, the contacts .of this switch close the power supply line Ll' and control 'circuit line Cl, this line including an air-pressure actuated switch`K3. and an overload relay 'switch Kl, the latter -forming a part of thermal overload relay R, the circuit being completed to power supply 'line L5, through the actuating coil of the starter.

Closing of the maintaining contact switch K2 closes the starter SI, and simultaneously, the closing of auxiliarycontacts K5, forming a part of the starter, closes the low voltage supp1y,through line L4 tothe actuating lcoil of starter S2, the opposite side of the actuating coil of starter S2 being fed by the normally closed contacts Klof the instantaneous overload relay Rl. to close starter S2 simultaneously with starter SI, whereby both the screw shaft motor MI and the feeder motor M2 will be started together. v

I'he closingof starter SI isonly possible when the pressure switch K3 is closed. This switch is of the conventional diaphragm type and may conveniently be connected to the air supply through suitable tubingv from the connection I9.' Should the airsupply pressure to the air-ring I6 drop below a predetermined point, or fail entirely, this switch willopen, de-energizing the actuating coil 4 and releasing starters SI and S2 causing the pump to stopbefore un-aerated material -is forced into the conduit 22.

The instantaneous overload relay RI, referr to above, is of the adjustable type including the usual solenoid plunger and dash-pot, and, experience has shown that the most satisfactory This starter is likewise of the full relay is one actuatedat about of full load, at which time it will open the contacts KI, thereby releasing starter S2, to stop the feeder motor -M2, when screw shaft motor Ml is overloaded found to be satisfactory for a general purpose, I

squirrel cage induction motor.

The circuits for actuating the starters of thel wheel motors M3 and M4 are closed `by switches preferably of the mercury contact type, the latter being assembled in a housing in the form of a handle, asA illustrated in Fig. 7. In Fig. 6, these switches are shown in plan in the positions actually occupied in the handle, the switches being marked for simplicity RF and LF, representing right-wheel forward and left-wheel forward, and LR and RR, representing left-Wheel reverse and right-whelreverse. Each of these switches is tilted about 15 degrees from the horizontal with the contacts elevated to keep the circuits open when the handle is held vertically, with the switch K2 upward. I

There are four normal and four intermediate directions for tilting the handle. The operator normally faces the'pump and holds the handle in front of him in the upright or normal posir tion, withtheswitches in the horizontal position shown diagrammatically in plan in Fig. 6. By tilting the handle forwardly from this position, circuits will be closed through the switches RF and LF, and it-will be realized that both wheel motors M3 and MI will rotate the right-wheel RW and left-wheel LW to move the pump forwardly. Tilting the switch assembly in the oppo- 1 site direction, normally toward the operator who usually faces the machine, will close the circuits through the switches LR and RR to reverse the operation and move the pump backwardly'.

Similarly, tilting the switch to the left will close f circuits to the switches RF-and LR, to cause the left wheel LW tg reverse and RW to turn fore wardly, thereby swinging the pump around a substantially fixed pivot toward the left. Similarly,

tilting the switch assembly toward the right will A switch KE of the normally open pushbuttonl Y type is included in the switch assembly andcon- .nected in line LI, the switch being so located that it may be conveniently held in closed position vby the operator when he desires to move the pump in .any direction- The purpose of this switch vis to make the wheel lmotor controls inoperative except when it is closed to prevent accidental movement of the 'apparatus if the operator desires to leave the pump inv operation and place Vthe switch assembly at any convenient point, at which time all of the circuits through the mercury type switches will be opened. The switch K6 closes a circuit through a control line C2. common to each of the mercury type switches.

, Switch RF includes a second line C3 which 'closes a circuit through the forward actuating coil AI of the starter S3, the circuit being closed when the switch RF is tilted from the position l the pump. A second terminal block 84 is proj vided for a cable 85 including the control circuit illustrated. Switch LF includes a second line C4 which closes a. circuit through the forward actuating coil. A2 of the starter S4, to drive the motor M4 forwardly, as above described. Switch LR includes a second line C5 which energizes the reverse actuating coil A3 to close the reversing section of starter- S4 to cause the motor M4 to reverse andg rotate wheel LW in the reverse direction. Switch RR includes a second line C6 which energizes al circuit through the reverse actuating coil A4 to close the reversing section of starter S3.' Y

The operation of the apparatus will be generally apparent from the foregoing. Assuming that the pump is to be used for unloading boxcars of cement, the operator holds the pushbutton switch K6 in closed position and tilts the switch assembly in the necessary directions to cause the pump to move from the platform into the car and advance to a point where the feed disc 5 enters the stored cement. He then opens the air supply to air-ring I6 through the cocks' I1 and I8 and immediately closes switch K2 to start motors MI and M2. Further operation merely involves tilting the switch assembly to cause the pump to keep in contact with the material, with the feed disc 5 wholly or partially submerged. The maximum capacity rate is maintained by tilting the switch alternately to the right and left at frequent intervals, as the pump advances, to cause the feed disc' to swing about relatively wide arcs to recover vthe material over a relatively wide area. The rod I2 assists in breaking down the face of the pile so that the feed disc. will undermine the cement and move it rapidly into the hood 4 where it is picked up by the screw flights I5. When heavy slides of cement descend upon the feed disc, and particularly'when the cement has been stored for a considerable period and is densely compacted, the screw shaft driving motor MI may be overloaded. When this overload equals the setting of relay RI, the contacts lKI are opened thereby deenergizing the4 holding 'or actuating coil of starter S2, the latter releasing and stopping motor M2. As the flow of material into the hood 4 decreases the motor load falls, releasing the contactor of relay Rl to close the circuit through the contacts KI and the actuating coil of starter S2, to start motor M2.

The thermal overload relays R protect motor MI fromy too frequent overloading. 'I'he wheel motors M2 and M4 have sufficient power to move the machine under all normal conditions, and the pump may be moved forwardly against the stored cement until these motors are stalled, when if the operator fails to tilt the switch assembly to open the switches RF and LF, the

thermal overload relays, such as at R3, open the circuits, thereby protecting the motors.

The starters are preferably arranged on a panel 80, which may be enclosed in a suitable dust-proof casing (not shown). The panel is provided with a terminal block 8| to which the wires of cable 82 may be connected, the cable terminating in a -terminal block 83 secured to wires, the cable terminating in the remote control switch assembly. A

It will be understood fromthe foregoing that the operator can force the pump into the cement at all times to maintain a maximum rateA of pumping without damage to the apparatus or causing the motors to oe-dangerously,overloaded.

I1, to the conduit until the latter has been cleared of materiaLas indicated by a transport line pressure gauge 11, on panel 18, when the gauge shows a lack of back-pressure. This gauge is connected by suitable tubing (not shown) to the body of the non-return valve and also serves to indicate` the operating pressure of the pipe line system when the apparatus is in normal operation. A

second gauge 19 may be arranged on the panel and connected to the air connection I9 beyond the cock I8, to indicate the air-ring supplypres- Sure.

I claim: L. 1. In a portable apparatus for receiving p ulverulent material and conveying it through av pipe line, the improvement which comprises the combination of a pair of supporting wheels, a yoke adapted to be secured to an element of the apparatus, a gear case at each'end of the yoke, each case having an axle supported lfor rotation in spaced bearings therein and extending beyond a wall thereof, the outer end of each axle being secured to a supporting wheel, similar means for driving each axle independently of the other in either direction, each including a reversible, alternating current electric motor, a reversing starter for the motor, a worm and a worm gear driven thereby, the worm being secured to the axle between the bearings.

2. In a portable apparatus for receiving pulverulent material and conveying it through a pipe line, `the improvement which comprises the combination of a pair of supporting wheels,a yoke having a central opening to surround an element of the apparatus, the yoke being adapted to be secured thereto, a gear case at each end of the yoke, each case having an axle supported for rotationin spaced bearings therein and extending beyond a wall thereof, the outer end of each axle being secured to a supporting wheel, similar means for driving each wheel independently of. the other in either direction, each including a reversible alternating current electric motor, a reversing starter for the motor,'a worm for driving each wheel independently'of the other v in either direction, each said means including a reversible, alternating current electric motor and speed reduction gearing, a reversing maglnetic starter for the motor having a forward section and a reversing section, each of said starters, including both sections, being independ- I ently supplied from a common power supply, a-

manually operated switch in the actuating-coil circuit of the forward section of the starten, and a second manually operated switch in the actuating-coil circuit of the reversing sectiongof the starter. n

4. In a portable apparatus for receiving pulverulent material and conveying it through a pipe line, the improvement which comprises the combination of a pair of supporting wheels, a. separate vaxle, for each wheel and similar means for in either direction, each said means including a reversible, alternating current electric motor and speed reduction gearing, a reversing magnetic starter for the motor having a forward section and a reversing section, eachof said starters, including both sections, being independently supplied from a common power supply, the forward actuating-coil circuit and the reverse actuatingcoil circuit of the starter including wires enclosed by a flexible cable, the cablel terminating in a portable switch assembly and a manually operated switch in each of said circuits arranged in the switch assembly.

5. In aportable apparatus for receiving pulverulent material and conveying it through a pipe line, the improvement which comprises the combination of a pair of supporting wheels, a separate axle for each wheel and similar means for driving each wheel independently of the other in either direction, each said means including a reversible, alternating current electric motor and speed reduction gearing, a reversing magnetic starter 4for the motor having a forward section and a reversing section, each of said starters, including both sections, being independently's'upplied from a common power supply, the forward actuating-coil circuit and the reverse actuatingcoil circuitof the starter including wires enclosed by a exible cable, the cable terminating in a portable switch assembly, and amanually operated switch in each of -said circuits, the switches having a common power supply wire, and a normally open manually operated switch in said wire, all of said switches being arranged in the switch assembly. l

6. In a portable apparatus for receiving pulvern ulent material from a pile and conveying it through a pipe line, the improvement which comprisesA the combination of a pair of supporting wheels, a. separate axle for each 'wheel'and similar means for driving each wheel independently of the other in either direction, each said means including a reversible electricmotor and speed reduction gearing, a reversing magnetic starter for the motor, the forward actuating-coil circuit and the reverse actuating-coil circuit of the starter including wires enclosed by a flexible cable, the cable terminating in a portable switch assembly, and a switch of the mercury` contact .type in eachl of said circuits. the switches being enclosed by a portable switch assembly andl located at opposite sides thereof, so that tilting the assembly in one direction will close the circuit through the switch in the forward actuating-coil circuit and tilting it in the opposite direction will open said switch and close the switch in the circuit of the reverse actuating-coil.

7. In a portable apparatus for receiving pulve i ulent material from apile and conveying it through a pipe line, the improvement which comprises'the combination of a pair of supporting wheels, a separate axle for each wheel and similar meansfor driving each wheel independently of the other in either direction, each said means including a4 reversible electric motor and speed reduction gear-A, ing, a reversing magnetic starter for the motor,

the forward actuating-coil circuit and the reverse actuating-coil circuit of the starter including wires enclosed by a flexible cable, the cable terminating in a portable switch assembly; a switch of the mercury contact type in each of said ciropposite direction will open said switch and close the switch in the circuit of the reverse actuatingcoil, each of the mercury contact switches having a common power supply wire, and a normally open manually operated switch in said wire to keep said actuating-coil circuits open until an operator desires to move the apparatus.

8. In a portable apparatus for receiving pulverulentmaterialfroma pile and conveying it through a pipe line, the improvement which comprises the combination of a right and a left wheel for supporting the apparatus, Aa separate axle for each wheel and similar means for driving each wheel independently of the other in either direction, each said means including a reversible electric motor and speed reduction gearing, a reversing magnetic starter for each motor, the forward actuating-coil circuits and the reverse actuating-coil circuits of both motors including wires enclosed by a cable terminatingin a portable switch assembly, said assembly enclosing four switches of the mercury contact type, one in each of said actuating-coil circuits, the switches being inclined from the horizontal with the contacts `elevated in open position in a normal position in one direction, those in the reverse actuatingcoil circuits are closedwh'en theb assembly is tilted in the opposite direction, and, one switch in a forward and one switch in a reverse actuating-coil circuit areclosed when the assembly is tilted at right angles to said directions.

, 9.. In a portable apparatus for receiving pulverulent material from a pile and conveying it through -a pipe line, the improvement which comprises the combination of a right and a left wheel for supporting the apparatus, a separate axlefor each wheel and similar means for driving each wheel independently of the other in either direction, each said means including a reversible electric motor and speed reduction gearing, a reversing magnetic starter for each lmotor, the forward actuating-coil circuits and the reverse actuating-coil circuits of both motors including wires enclosed by a cable terminating in a portable switch assembly, said assembly enclosing switches in the right wheel motor actuating circuits, whereby the wheels may be driven together either forwardly or rearwardly, or oppositely byY closing said switches in pairs, or either wheel may be driven in either direction by tilting the as- 4 sembly to close a single switch.

HERBERT s. LENHART.

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