US2040660A - Feeding and batching apparatus - Google Patents

Description

y 1936- H. s. LENHART 2,040,660

FEEDING AND BATCHING APPARATUS Filed May 14, 1955 5 Sheets-Sheet l INVENTOR H. S. LiNHAHT EML 0km 'ATTORNEYS May 12, 1936. H. s. LENHART 2,040,66

FEEDING AND BATCHING APPARATUS Filed May 14, 1935 3 Sheets-Sheet 2 nun IIIIIIIl/IIIIIIIIIIIIIIII lNVENTOR 6,, 8 H. 5. LUV/MR7" [IA- BY 8 .12 Q M z iww g ATTORNEYS Patented May l2, 1936 UNITED STATES PATENT OFFICE 2,040,660 FEEDING AND BATCHING APPARATUS Herbert S. Lenhart, Allentown, Catasauqua,

Fuller Company, tion of Delaware Pa., assignor to Pa., a corpora- Application May i4, 1935, Serial No. 21,335 11 Claims. (Cl. 249-45) This invention relates to'a feeding and weighing apparatus, and more particularly to an appatating parts of mechanical feeders. Heretofore, this has required expensive and specially designed feeding apparatus to avoid the withdrawal of an excessive quantity of material. Such excesses not only involve serious cumulative losses but prehandling materials such as cement raw materials, lime, soda ash and others which can be handled by a mechanical feeder.

For batching Portland cement, it is essential that the feeding apparatus withdraw the material rapidly at a uniform rate, for otherwise the quantity of material withdrawn cannot be controlled accurately within the permissible limits of tolerance of over or under-weight., ,Such variations delay the discharge of the batches, as will be explained useful rate.

' bination of a mechanical feeder for more fully hereinafter, and thereby prevent operation of the apparatus at a only start the initial plished by remote control provided only that each batch is within a permissible tolerance over or below the pre-determined weight. All other operations are automatic and beyond his control.

In general, my invention comprises the comwithdrawing the material at a uniform rate and a valve mechanism which serves as a positive means to interrupt the flow of material when the desired quantity has been withdrawn, to prevent the discharge of an over-weight due either to a flood of ceoif, due to the momentum of the rotating part or The feeder discharges into a batch hopper or scale pan which may be supported by conventional scale elements such as those of a beam The batch hopper may be discharged by a gate or valve of any suitable type.

The feeder is an improvement over that disclosed in the Morrow patent in that it is considerably less expensive, as such is not essential, and includes a positive means for relieving the pressure-head of material upon the feed roll as well as means to shut oi? the flow of cement, including that retained in the flutes or pockets in the roll. The feed roll rotates within a drum-type gate or valve having oppositely arranged sealing elements which, when the flow of cement is interrupted close both the inlet and discharge openings of the feeder feed roll and gate valve are independently driven feeder casing or its flange. hopper is preferably closed of canvas or the like,

The top of the batch by a flexible apron which is also attached to the lower flange of the feeder casing. The batch hopper or scale pan is preferably discharged through a rotary gate valve similar to that enclosing the feed roll, whereby the cement may be For simplicity, the apparatus will be described in combination with a scale of the double beam type, but it is to be understood that other scales of conventional type may be utilized. When a double beam scale is used, the poise or counterweight on the tare beam is moved to balance the tare weight of the scale pan and its associated parts. It is preferably equipped with a tell-tale index or pointer to indicate to the operator that a batch of permissible weight has been withdrawn and that the batch hopper can be discharged. Certain of the control switches, the function of which will be described hereinafter, are operated by the tare beam and may conveniently be combined with the operation of the tell-tale.

When the apparatus is first placed in service, the desired pre-determined weight is established by making the proper adjustment of the poise on the balance beam. If desired, a casing may be provided to surround the apparatus, or the beam box may be locked to prevent unauthorized changes in the batch weight.

In brief, the operation of the follows:

Assuming that the scale elements have been adjusted, as described above, and the hopper discharge gate is closed, closing of the power service switch energizes both the power supply and control circuits. The feed roll and the double gates which surround it start simultaneously, the gate rotating a quarter of a turn to its fully opened position, whereupon the circuit to its driving motor is opened and further rotation prevented by a spring-actuated magnetic brake. The feed roll continues to operate until the quantity of cement deposited in the hopper or scale pan approaches the pre-determined batch weight, whereupon the circuit to the feed roll driving motor is opened and the gate motor circuit is again energized causing the gate and roll to turn together until the gate is entirely closed. This not only offers positive protection against nooding but also prevents the discharge of an excessive quantity of material due to over-running of the roll as a result of its momentum. The control circuits are so adjusted that the material falling between the feeding apparatus and the apparatus is as batch hopper, that is the material in suspension the. discharge gate motor circuit .to the motor and a when the feeder gate is closed, equals the necessary additional quantity of cement to provide for a batch weight within the desired limits of tolerance.

For convenience, the circuit controlling-the discharge gate may be provided with a push-button switch or the like, which controls the operation of the driving motor. The discharge gate may be opened successively increasing distances to prevent sudden discharge of cement by closing the push-button switch for short successive intervals. The gate cannot be closed,.however, or the feeder started until it has reached its fully open position and the hopper has been completely discharged with the tare beam again in balance. To

expedite the complete discharge of the hopper,

7 the V actuated when the gate reaches its fully opened position.

'As soon as the tare beam returns to balance,

is closed autois opened both magnet which releases a spring-actuated magnetic brake on the motor shaft. At this time the feeder and its gate motor circuits are again energized and the next batch matically, after which the circuit 'paratus may is withdrawn automatically in a similar manner.

In order to prevent interruption of the operation, due to the entrance of foreign material which may lodge between a wall of a pocket of the feed roll and an edge of the gate, the sealing elements of which serve as the side walls of the feeder casing when in open position, the feed roll is automatically reversed in direction of rotation by the provision of two starters of the magnetic type, one of which is normally closed, the other serving to reverse the phase. Each starter includes a thermal overload relay which becomes overheated when the driving motor is overloaded. The release of this relay de-energizes the starter magnet and actuates the other starter to reverse the motor. Ordinarily this reversal will dislodge the foreign material, unless it is of unusual size and causes it to be ultimately discharged to the scale pan. The roll will then run in the new direction until a similar overload occurs, whereupon the second starter is released and the other is closed.

It will be realized from the foregoing that the operation of the apparatus requires no manual intervention other than the closing of a switch to discharge the batch, all other operations being completely automatic. This prevents delaying the rate of withdrawing and discharging successive batches without sacrificing any of the advantages of the in preventing the discharge of a batch below or above the permissible tolerance in pre-deterinined batch weight.

For a better understanding of the invention, reference is made to the accompanying drawings in which:

t Fig. l is a side elevation of the complete appara- Fig. 2 is a fragmentary detail of the scale beam 4 and tell-tale;

Fig. 3 is a plan view' of the feeder with the gate open;

Fig. 4 is a longitudinal section of the feeder with the gate closed.

Fig. 5 is a cross-section of the feeder on line 5-5 in Fig. 4, and

Fig. 6 is a wiring diagram of the power and control circuits, with all elements illustrated in the positions occupied before the circuits are energized, and with the hopper discharge gate in fully closed position, the power circuits being shown in bold and the control circuits in light lines.

Referring to the the apparatus will chanical feeder, the conveniently to paratus about drawings, and first to Fi 1,

support the remainder of the apto be described. The entire apflange of the feeder to a corresponding flange on a cement storage bin (not shown). A batch hopper or scale pan 2 is carried by the lever elements of the scale, indicated generally at 3 which are in turn supported by brackets 4 secured to frame members 5 which also support the scale beam bOx. 8. i

that the feeding having an upper flange 1, intended to be secured to a supply bin, spout or the like (not shown), and a lower flange}. The walls'at the inlet port of the casing slope inwardly as at 8 to conduct the cement to a mechanical feeding device preferably comprising a feed roll in, provided with parallel flutes or pockets l l to convey the cement single Morrow apparatus be seen to consist of a mecasing of which may be used be supported by securing the upper By reference to Figs. 3', 4 and 5, it will be seen", apparatus comprises ,a casing Til v sufficient diameter to permit the-removal the roll I The motor relatively low power, as

to the discharge port I2, the pockets being preferably of uniform size so that the flow of material will not be erratic. Feed roll I0 is hollow and its interior surface is preferably irregular or corrugated as indicated at I3 whereby one or more weights such as the balls I4 will serve to vibrate the apparatus sufficiently to discharge cement from the pockets II and thereby provide for high capacities and uniform feeding. The balls I4 likewise serve to prevent the material from lodging between the ends of the roll and the parts about to be described, thereby reducing wear and friction between the parts. For purposes of economy, is preferably cast as a single piece, the balls being supported by wires in the core and freed after the sand is withdrawn from the castmg.

The feed roll rotates within a drum-type gate I5 preferably provided with oppositely arranged gate members I6 and I! whereby both the inlet and discharge ports of the casing may be sealed completely and the roll 0 totally enclosed, the gate members serving as the side walls of the cas ing when the gate is fully open. The casing is bored longitudinally so that the inner edges I 8 of the sloping walls 9 of the inlet and outlet ports are concentric to the gate, and a minimum clearance is provided whereby the cement will be prevented from flowing between the outer surfaces of the gate members I6 and I1 and the surfaces I8 when the gate is in closed position. The gate members I6 and I l are secured to end plates I9 and provided respectively with hollow shafts 2I and 22 which rotate in bronze bearings 23 and 24 which also serve as packing glands, the latter being secured to circular end plates 25 and 26 which close the ends of the casing and are of of the gate I5 and feed roll I0. The shaft 22 is rotated througha flexible coupling 21 secured to the speed reducer shaft 28 of a motor 29 of the usual type combined with reduction gearing and a spring actuated magnetic brake, to be described hereinafter in connection with the operating circuits. may conveniently be supported by a bracket 30 secured to the casing of the feeder.

The feed roll I0 is carriedby shafts 3| and 32 the latter turning in a bronze bushing 33, which likewise serves as a packing gland.- Shaft 3| turns in a. bushing 34 carried by the hollow shaft 2| and is driven through a flexible coupling 35 by a motor 36, also-provided with reduction gearing, but not including a brake, as continued operation of the feed roll I!) due to its momentum is harmless since either of the gate elements I6 or I1 will have closed the discharge port I2 when the flow of cement is to be stopped. as will be explained hereinafter. The motor 36 may be of compared with that disclosed in the Morrow patent, since a gate element, such as I6, protects the roll Ill from the pressure-head of material in the storage bin and thereby reduces the starting torque, as the preferred method of operation is to start rotation of both the roll Ill and the gate I5 simultaneously.

For purposes of economy, in construction and to reduce wear and friction losses, a substantial clearance may be provided as at 31 between the ends of the feed roll I0 and the end plates I9 and 200i the gate I5. This clearance together with the vibrating effect of the balls I 4 prevents the packing of cement between the adjacent surfaces and allows the material to discharge freely when the gate is open. For convenience in assembly, the inner end walls of the casing are provided with bosses 38, to support the feed roll 'be'fore end plates I9 and 20 are secured to the casing.

It will be seen that the gate I5 and feed roll Ill are arranged to move independently and as these parts are symmetrical they may turn in either direction. As will be described in connection with the operation of the apparatus, it will be apparent that if foreign material tends to lodge between an edge of a pocket II and a surface I8 of the inlet, that reversal of the direction of rotaion of the feed roll will permit the material to be discharged unless it is of unusual size.

Again referring to Fig. 1, it will be seen that the hopper 2 is discharged by a gate 40 preferably of the rotary type havingopposed sealing ele-.

ments substantially similar to feeder gate I5, or that disclosed in the Morrow patent. This gate may be driven through a flexible coupling 4| by a motor 42, preferably of the type provided with reduction gearing and a magnetically operated spring-set brake. The other shaft of gate 40 serves to operate a drum switch or commutator 43 the function of which will be described hereinafter. A magnetic vibrator M, of conventional type is preferably secured to a wall of the hopper 2 to provide for the rapid and complete discharge of material. i

The scale elements may be of conventional type and comprise a tare beam 45 provided with a loop 46, beam 41 which carries the usual poise 48. A tell-tale 49 comprising the usual scale and index 50 serves two functions, first to indicate to the operator that a batch can be discharged and also to actuate certain of the control circuits. To this end the tell-tale includes a pivotly mounted support 5l actuated by the fare beam 45 through a link 52. If these control switches are of the mercury contact type, the support 5| is provided with clips having set-screws 53 whereby the angular position of the switches may be so adjusted that the'apparatus will function within desired limits. It will be recalled that the beam box is ordinarily closed and locked during normal operation, and a tell-tale is accordingly desirable. The lever elements of the scale, generally indicated at 3, are connected to the tare beam through the usual link 54.

The power and control circuits which cause the apparatus to function in the preferred manner are illustrated in Figs. 6, in which the associated elements are indicated in the positions occuplied with'none of the circuits energized and-with the lower gate 40 in its fully closed position. The telltale, "is shown with the index and its switches at neutral position with the tare weight of the hopper 2 and associated parts in balance. The preferred cycle of operation is briefly as follows:

When the power service switch (not shown) is closed, the upper gate I5 immediately begins to open and simultaneously the feed roll I0 starts rotation. The gate I5 opens only to its fully open position but the roll III continues to operate until the weight of material inthe hopper or scale pan 2 approaches the pre-determined weight as established by the adjustment of the poise 48 on weigh beam 41. The roll is stopped and the gate closed prior to the deposit of the entire batch in the hopper to compensate for the weight of the material falling in suspension. When the gate I5 begins to close the motor 36 is de-energized whereby the gate and roll travel together to the closed position. Assuming that the batch is within the pre-determined limits of tolerance which engages the end of the weigh gate I! ginedto ergiae the magnet of starter SI by weight, the circuit to the motor l2 may be energized to open gate 40. This gate can be opened in steps, but it cannot be reversed thereby preventing the operator from retaining any material in the batch hopper. when the tare beam comes to balance after all material has been discharged, the lower gate is closed automatically without manual intervention. The vibrator ll begins to operate after this circuit is closed, the gate is fully opened and continues only as long as the push-button is closed.

In Fig. 6 all power circuits are indicated by bold lines, the control circuits being indicated by light lines. Closing oi the power service switch (not shown) energizes lines Ll, L2 and L3 and causes circuits represented by power line line Ci through a commutator ring 55 of the drum switch 43 secured to the shaft the discharge gate 40. At the same time this closes the circuit through starters SI, and 83 which control respectively the driving motor 18 of the feed roll- II and the motor 20 of the gate l6. Simultaneously to the closing of the circuit to motor 2! the magnets ot a spring-set brake Bl are enerwhen the gate l rotates a quarter of a turn from the position illustrated in Figs. 4 and 5, to its fully open position, Fig. 3, a cam 28 having two oppositely arranged cam surfaces opens a limit switch 51 thereby opening circuit LI and C2, causing therelay R! to return to open position and de-energize the magnet of starter 88, at which time the motor 29 and the magnet of brake BI is released and as the latter is spring-set it immediately prevents the motor and gate; II from overrunning, thereby holding the gatei in its tully'opened position.

As' the gate i5 is now fully opened and the feed roll it is delivering material to the scale hopper 2, motor it continues to operate until the weight approaches'the desired limit, less the weight oi the material that will fall in suspension after is closed. At this time the scale beams move a sutflcient distance to tilt the support I, which actuates tour switches,'which may be of the mercury contact type. Switch 59 is adjusted angularly whereby the circuit about to be described is closed by a sufllcient movement of the scale beams to compensate for the material ralling in suspension. Closing of the switch ll closes circuits LI and C3 and energizes relay RA through the contacts of which and relay RI circuits are closed through lines C2 and C4 to ento close the latter to start motor 2! and energize the magnets of brake Bl to release the motor shaft. The

motor rotary gate I! again rotatesa quarter of a turn to its fully closed position, at which time the' cam, 58 closes the limit switch 51 through the circuits represented by lines Li and C2, thereby energizing the magnet oi! relay RI and de-energizing the magnet of starter S! which stops the motor and causes the brake Bi to engage the shaft. At the same time, when starter S3 is closed, the magnet 0! starter SI is tie-energized causing the circuit to motor 28 to be opened to stop rotation of the feed roll Ill. As explained above, motor I! is not provided with a brake as over-running of roll Ill does not discharge .an

' excessive quantity of material, as the roll is now totally enclosed by the gate I.

The material falling between batch hopper 2, aiterthe gate the batch up to the desired the ion is and is closed, brings pre-determined release the brake from the shaft of the weight and the proper angular adjustment or switch 5!, to make a compensation for this quantity, can best be determined by three or four trials alter the apparatus has been installed. Switches 60 and 6! on the tell-tale support 5| are oppositely arranged and are to control the discharge gate operating circuit so that the gate cannot be opened unless the batch weight is satisfactory, the circuit being completed through both switches. The limits of tolerance are adjusted by varying the angles of these switches from the horizontal. Decreasing the angles reduces the degree of tolerance.

Assuming that the circuit is closed through switches 60 and 6 I, at which time the weigh beam is in balance, closing of the push-button switch 62 energizes relay R6 through circuits L2 and C5, the contacts of the relay closing circuits C6 and C1 which energize the magnet to close starter S4 through the contacts of relay RI.

Closing of starter SI energizes the magnets of the springset brake B2 releasing the latter and starting motor 42 to open the gate 40. When this gate moves a quarter turn the commutator ring 551 closescircuits L3 and C8 thereby energizing-relay Ri and opening circuit C6, de-energizing the magnet of starter S4 and causing the latter to open, at the same time opening the circuit to magnetic brake B2, which being spring-set stops the motor 42 from over-running.

When the circuit including the lines L2 and C6 is energized, a circuit is completed to a magnetic counter 62 provided with the usual release coil 64 and latch coil 65, a counter of the mechanical latch type' being preierred as repeating is prevented unless the latch is flrst released by coil 85.

If desired, the gate may be opened slowly by repeatedly closing push-button 62 for short successive intervals, but as'will appear hereinafter,

' it cannot be closed manually or otherwise until the hopper is empty. Continued closing of the push-button 82 after the gate is fully opened energizes the vibrator through circuits C9 and L2.

Further, when the circuits controlling the opening or discharge gate 40 are energized, the solenoid i8 is energized through circuits CH and L2 through the contacts of relay R2, relay R2 being released when the gate begins to open due to the opening of the circuits through lines CI and L3, through the commutator 55. The solenoid 66 serves to lift the weigh beam 41 from the loop 4 suspended from tare beam 45, thereby tare weight to be balanced when all 0! the material has been discharged from hopper 2. when the tare weight is in balance, a circuit through lines CIB and LI is closed through mercury switch 61, carried by the tell-tale support 5| through the contacts 0! relays R6 and RI, thereby closing starter S4 and energizing the magnets oi brake B2 to cause motor 42 to close the gate 40 automatically. When this gate is fully closed, commutator again assumes the position illustrated, opening circuits C8 and LI to release relay RI, which upon opening breaks the circuit through CIB and releases the magin the same circuitreleases the mechanical latch oi the counter by energizing the release coil 84 through the circults CH and L2.

Should ioreign materialstop the feed roll it,

a thermal overload relay 82 in the starter SI discharged to the batch hopper.

overheats and opens the circuit through the magnet to release the starter. This also causes the release of relay R3 which closes its normally closed contacts and completes a circuit to the starter S2, which as the diagram shows, is oppositely connected to reverse the phase of the power circuit, and thereby the direction of rotation of motor 36 to cause roll [0 to change direction. Unless the material is of usual size it will assume a position within a roll pocket and clear the surface l8 of the feeder casing and ultimately be The roll ID will continue to turn in the new direction, opposite the direction of gate l5, until foreign material is again engaged between the feed roll and gate, whereupon a similar thermal overload relay 69 releases starter S2 and reverses the direction of rotation, provided the thermal overload relay 68 has cooled sufficiently to complete its circuit.

The operation of the apparatus will be apparent from the foregoing description and itwill beseen that the sole function of the operator is to discharge the batches-by remote control in the oper- V ation of the push-button switch or its equivalent.

Although he can obviously stop the operation of the entire apparatus by opening the power circuit he cannot discharge a batch. If it should be desired to discharge a batch of more than the allowable weight deposited in the hopper by damaged apparatus, the casing which usually surrounds the apparatus or the cover of the beam box (not shown) may be unlocked and the scale brought to balance thereby closing mercury-contact switches 60 and GI, whereby the circuit to the motor 42 may be completed by closing the push button switch 62.

I claim:

1. An apparatus for withdrawing batches of pro-determined weight of bulk materials from a storage bin comprising the combination of a scale, a batch hopper supported by elements thereof, the hopper being provided with a discharge gate, means for withdrawing materials at a uniform rate and depositing them in the hopper including a casing having inlet and discharge ports, a mechanical feeder within the casing, a motor for driving the feeder, electrically actuated gate members closing the inlet and discharge ports of the casing, electrically actuated means for driving said members, control circuits for the motor and said electrically actuated means including switch means movable to closed position by an element of the hopper discharge gate when the latter closes to energize the motor and gate actuating means to drive the feeder and open the gate members.

2. An apparatus for withdrawing batches of pre-determined weight of bulk materials from a storage bin comprising the combination of a scale, a batch hopper supported by elements thereof, the hopper being provided with a discharge gate, means for withdrawing materials at a uniform rate and depositing them in the hopper including a casing having inlet and discharge ports, a mechanical feeder within the casing, a motor for driving the feeder, a gate member closing the casing to the flow of material, a motor for driving the gate member, and a control circuit therefor including a switch movable to closedposition by an element of the hopper discharge gate as the latter closes to energize the motor to open the gate.

3. An apparatus for withdrawing batches of pre-determined weight of bulk materials from a storage bin comprising the combination of a scale, a batch hopper supported by elements thereof, the hopper being provided with a discharge gate, means for withdrawing materials at a uniform rate and depositing them in the hopper including 'a casing having inlet and discharge ports, a mechanical feeder within the casing, a motor for driving the feeder, a rotary gate having oppositely disposed gate members closing the inlet and outlet ports of the casing, a motor'for driving the gate, a controlcircuit for said motor including a switch movable to closed position by an element of the hopper discharge gate when the latter closes to energize the motor, and a second switch in said circuit movable to open position by an element of the gate to de-energize the motor when the gate has rotated one quarter turn.

'4. An apparatus for withdrawing batches of pre-determined weight of bulk materials from a storage bin comprising the combination of a scale, a batch hopper supported by elements thereof, the hopper being provided with a discharge gate, means for withdrawing materials at a uniform rate anddepositing them in the hopper including a casing having inlet and discharge ports, a

feed roll, provided with material receiving pockets,

within the casing between said ports, a motor for driving the feeder, a rotary gate having a gate member concentric to the feed roll and closing a. port of the casing, a motor for driving the gate, control circuits for said motors including switch means movable to closed position by an element of the hopper discharge gate as the latter closes to energize the motors.

5. An apparatus for withdrawing batches of predetermined weight of bulk materials from a storage bin comprising the combination of a scale, a batch hopper supported by elements thereof, the hopper being provided with a discharge gate, means for withdrawing materials at a uniform I rate and depositing them in the hopper including a casinghaving inlet and discharge ports, a feed roll, provided with material receiving pockets, within the casing between said ports, a motor for driving the feeder, a rotary gate having oppositely disposed gate members surrounding and concentric to the feed roll, and closing the inlet and outlet ports of the casing, a motor for driving the gate, control circuits for said motors including switch means movable to closed position by an element of the hopper discharge gate as the latter closes to energize said motors, and a limit switch in the circuit of said gate driving motor movable to open position by an element of said gate to de-energize its motor when thegate has rotated a quarter turn.

6. An apparatus for withdrawing batches of pre-determined weight of bulk materials from. a storage bin, comprising the combination of a 'scale, a batch hopper supported by elements thereof, the bottom of the hopper being provided with an electrically actuated discharge gate, a closing circuit therefor including a switch movable to closed position by a movable element of the scale when the hopper is completely empty to move the gate to its fully closed position automatically, means to withdraw materials at a uniform rate from the storage binandto deposit them in the hopper including a casing having inlet and discharge ports, a feed roll, provided with material receiving pockets, within the casing between the ports, a motor for driving the feeder, a rotary gate having oppositely disposed gate members surrounding and concentric to the feed roll, and closing the inlet and outlet ports of the casing, a motor for driving said rotary gate, control circuits for said motors including 7 switch means movable to closed position by an element of the hopper discharge gate as the latter closes to energize said motors, and a limit switch in the circuit of said rotary gate driving moto'r, movable to open position by an element of said rotary gate to de-energize its motor when the gate has rotated a quarter turn.

'7. An apparatus for withdrawing batches of pre-determined weight of bulkmaterials from a storage bin comprising the combination of a scale, a batch hopper supported by elements thereof, the hopper being provided with a discharge gate, means for withdrawing materials at a uniform rate and depositing them in the hopper including a casing having inlet and discharge ports, a feed roll having material receiving pockets wlthin the casing between the pockets, a motor for driving the feeder, a control circuit therefor including a switch movable to closed position by an element of the discharge gate as the latter closes to energize the motor, the motor having a power circuit equipped with two starters oppositely connected to reverse the phase to change the direction of rotation of the feed roll, each starter having an overload relay, one of the starters being normally closed but subject'to opening by operation of the relay, and means to close the other starter when the relay opens.

8. An apparatus for withdrawing bulk materials from a source of supply at a uniform rate, comprising the combination of a casing having inlet and discharge ports, a feed roll within the casing, provided with pockets for transferring material from the inlet to the outlet, and a rotary gate member concentric to the feed roll and movable to close-one of said ports to the flow 'of material, and to permit the free transfer of material in its open position.

9. An apparatus for withdrawing bulk materials from a source of supply at a uniform rate, comprising the combination of a casing having inlet and discharge ports, a feed roll within the casing, provided with pockets for transferring material from the inlet to the outlet, and a rotary gate having oppositely disposed gate members surrounding and concentric to the feed roll and movable to close the inlet and outlet ports, the gate members permitting the free transfer of material in open position.

10. An apparatus for withdrawing bulk materials from a source of supply at a uniform rate, comprising the combination of a casing having inlet and discharge ports, a feed roll within the casing, provided with pockets for transferring material from the inlet to the outlet, and a rotary gate having oppositely disposed gate members surrounding and concentric to the feed roll, the gate members serving to seal the inlet and discharge ports in closed position and to serve as continuations of the side walls of the casing when in fully open position, and permitting the free transfer of material in open position.

11. An apparatus for withdrawing bulk materials from a source of supply at a uniform rate, comprising the combination of a casing having 'inlet and discharge ports, a feed roll within the casing, provided with pockets for transferring material from the inlet to the outlet, and a rotary gate having oppositely disposed gate members surrounding and concentric to the feed roll and end plates beyond the ends of the feed roll, the end plates being provided with hollow shafts supported for rotation in the end walls of the casing, the feed roll being provided with shafts extending into said hollow shafts and arranged for rotation therein.

- HERBERT S. IENHART.

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