CA1125695A - Silo unloader lowering control - Google Patents

Abstract

SILO UNLOADER LOWERING CONTROL

ABSTRACT OF DISCLOSURE:
A top unloading silo unloader pendently supported from a tripod with a cable connected to a motor operated winch.
An automatic silo unloader let-down control is operably con-nected to the winch motor to energize the motor once during each revolution of the unloader to lower the unloader in the silo. The let-down control has a control switch mounted on the unloader which is actuated by the rotating part of the unloader once during each revolution of the part. An auto-matic time delay unit is adjustable to control the duration of operation of the winch motor thereby controlling the amount of let-down of the silo unloader.

Description

S~i~5 SUMMARY OF INVENTION:
The invention is directed to control means for locating a material unloading apparatus relative to material being un-loaded by the appara-tus. The control means is more particu-larly associated with a top unloading silo unloader and power operated winch connected to the unloader with a suspension cable. The control means has a control switch mounted on the unloader that is opened once during each revolution of the unloader. The control switch is connected in series with an automatic time delay unit having an adjustable component con-;; trolling the duration of operation of the winch motor. The i winch motor operates each revolution of the unloader to lower the unloader a predetermined amount in the silo. A continu-ous motor operating switch is included in the control means to provide the operator with means for continuously operating the winch motor to either raise or lower the silo unloader in the silo.
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IN THE DRAl~INGS:
Figure 1 is a foreshortened side elevational view of a tower silo, partly in section, and a top unloading silo un-loader equipped with an automatic silo unloader let-down con-, ~- trol;
Figure 2 is an enlarged perspective view of the silo un-loader support structure and slip ring assembly carrying the control switch of the automatic silo unloader let-down control of Figure l;
Figure 3 is a perspective view of the power winch used ; to lower the silo unloader in the tower silo;
Flgure 4 is an enlarged perspective view of the control switch of Figure 2; and . ` .

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Figure 5 is an electrical circuit diagram of the automatic silo unloader let-down control.

D~SCRIPTION OF PREFERRED EMBODIMENT:
Referring to Figure 1, there is shown a tower silo indi-cated generally at 10. Silo 10 is a conventional material storing structure having a cylindrical upright side wall 1l.
rein-forced with circular bands or hoops 12. Side wall 11 can be concrete or cement staves or made of plastic or metal mate-rial. Side wall 11 has a plurality of openings or doorways 1~ that are open to an upright chute 13. Chute 13 extends from the top to the bottom o:E side wall 11 and provides a passageway for directing material to the base of silo 10.
The top of side wall 11 is covered with an arched roof 15.
Animal feed 16, as silage, haylage, and the like, is stored in silo 10. Other types of materials can be stored in silo ` 10.
.: Animal feed 16 is removed from silo 10 with a top un-loading silo unloader indicated generally at 17. Unloader 17 operates to collect the feed and discharge the feed through a doorway 14 in the silo wall 11 into the passageway o-f chute 13. The feed falls down the chute passageway to the base ~ of the silo.
; Silo unloader 17 can be the silo unloader disclosed in U. S. Patent No. ~,170,385, or silo unloader shown in `. U. S. Patent No. 3,822,796; U. S. Patent No. 3,651~910;
U. S. Patent No. 3,5~7,283; and U. S. Patent No. 3,522,971.
Unloader 17 has an elongated feed collector 18 extended from the central area of the silo to wall 11. Collector 18 has conveying means, such as one or more augers for moving ~.

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J~15 the feed towarcl a transfer means 19. Transfer means 19 moves the feed through an out chute 41 which directs the feed through doorway 14 into chute 13. Transfer means 19 includes an im-peller rotatably mounted in an impeller housing for receiving the material from the collector 18 and discharging the mate-rial to out chute 41. A slip ring assembly 21 is mounted on top of transfer means 19. Slip ring assembly 21 can be con-structed in accordance with the transition assembly shown in U. S. Patents Nos. 3,181,715; 3,438,123; and 3,517,369. The slip ring assembly has a non-rotating upper portion and a rotating lower portion. Other types of slip ring assemblies can be used with silo unloader 17. Slip ring assembly 21 is used to conduct the electrical powel from the power line to the electric motor that drives the conveyor o:E collector 18 and the impeller of transfer means 19. A motor also drives drive wheel structure 20 operab:Le to move collector 18 around the silo.
As shown in Figures 1 and 2, a support frame indicated generally at 22 is mounted on s:Lip ring assembly 21. Support :
frame 22 comprises three bars Z3, 24, and 25 triangularly ori-` ented about slip rin~ assembly 21. Bolts 26 secure bars 23, 24 3 and 25 to the non-rotatable portion of slip ring assembly -.;` 21. A torque arm 27 is pivotally connected to frame 22 with a short sleeve 28. Sleeve 28 is secured by welds to bar 23.
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~ Torque arm 27 extends through a doorway 14 and engages silo ~ ' wall ll to maintain out chute 41 in alignment with the door-`: way 14.
Unloader 17 is pendently supported in silo 10 by a cable arrangement 29 and a single cable 31. A ring or loop connec-tion 32 connects the upper end of the cable arrangement 29 to single cable 31. As shown in Figure 2, the lower ends : . .

of cables 29 are connected l~ith an elongated eye bolt 33 attached with nuts to the outer ends of bars 23, 24, and 25.
The structure for supporting and holding cable 31 is herein-: a-fter described.
Referring to Figure 2, transfer means 19 has an impeller housing 35 having an upwardly directed discharge neck 36. An annular collar or plate 37 is secured to the upper end o~ neck 36. A square boot or tube 38 is mounted on plate 37 with a plurality of nut and bolt assemblies 39. Discharge chute 41 is pivotally connected to the discharge or upper end of slip ring assembly 21 whereby the feed moved by the impeller located in the housing 35 is moved upwardly through slip ring assembly 21 and directed laterally by discharge chute 41 toward door-; way 14.
~` Returning to ~igure 1, a tripod assembly indicated at 42 i.s mounted on top of silo wa:Ll 11. An example of the tri-~`, pod assembly is shown in U. S. ]?atent No. 3,211,407. Other types of support assemblies can be used to centrally locate cable 31 to pendently support silo unloader 17 in the silo.
20 Tripod assembly 42 has three legs 43, 44, and 45 joined at th.eir upper ends and supporting a rotatable pulley 46. Cable 31 is trained over pulley 46 and a second pulley 48 directing `.. : the cable downwardly to a power winch indicated generally at 49. Th.e lower ends of the legs 43, 44, and 45 each carry a ~oot 47 which supports the tripod assembly 42 on the top o~ ;
, si.lo wall 11.
-~ Power winch 49 is located on the outside o~ wall 11 adja-cent the base of silo 10. A pair of upright bars or angle irons 51 mount winch 49 on hoops 12. Suitable connectors, as .
U-bolts, attach bars 51 to hoops 12. Other structures can be used to attach the winch 49 to silo wall 11 or hoops 12. Also, .~ --5--, t~ '2 ~ ,~i..',~
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': ' :'` ' ~t'.`5~5 winch 49 can be attached to anchor structure fixed to the ground. Examples of winches for accommodating a cable used to support a silo unloader are disclosed in U. S. Patents Nos.
3,217,907 and 3,235,229.
Referring to Figure 3, power winch 49 has a frame indi-cated generally at 52 that is attached to upright bars 51 with suitable nut and bolt assemblies Frame 52 has a pair of flat side upright side plates 53 and 54 located in laterally spaced relation. Lower portions of plates 53 and 54 are secured to a pair of beams 56. A spool 57 is interposed between plates 53 and 54. Spool 57 is mounted on a shaft 58 extended to a gear box 59. Gear box 59 attached to the outside of plate 54 has a worm and worm gear arrangement. The worm is connected to an input shaft 61. The gear bo~ output shaft is the shaft 58. A second or counter shaft 62 extended parallel to the worm shat 61 is rotatably mounted in a sleeve 63. Sleeve 63 is secured to the bottom portions of beams 56. A chain and sprocket drive 64 drivably connects shafts 61 and 63.
~` A reversing electric motor 66 is operable to drive the worm gear shaft 61 and thereby selectively rotate spool 57 in opposite directions. Motor 66 is mounted on the bottom side of a plate 67. A plurality of downwardly directed brac-kets 68 mount plate 67 to beams 56. Motor 66 has a small drive pulley 69 aligned with a firs~ large pulley 71 mounted on coun-ter shaft 62. A V-belt 72 drivably connects the pulleys 69 and 71. A second V-belt pulley 73 is mounted on the worm shaft 61. The second pulley 73 is adapted to accommodate a second V-belt, shown in broken lines, in lieu of V-belt 72.
When V-belt 72 is drivably connected to the pulleys 69 and 71, winch 49 is operated at a slow speed. For high speed operation, a second V-belt is trained about pulleys 69 and ~ 5 73 whereby motor 66 is in a direct drive relationship with worm shaft 61 and rotates sha-ft 61 at a faster rate of speed than when shaft 61 is driven via the chain and sprocket drive 64 and pulleys and belt drives 69, 71, and 72.
The chain and sprocket drive 64 and the pulley and belt drives 69, 71, and 72 are enclosed within a shield 74, as shown in broken lines, mounted on a bracket 76. Bracket 76 is secured to the side of beam 56.
Cable 31 is wound around spool 57. Motor 66 is operated ; 10 to selectively rotate spool 57 in opposite directions and thereby raise or lower silo unloader 17 in the silo 11. An automatic let-down control system indicated generally at 77 is opera-tive to sequentially operate winch motor 66 to lower silo un-loader 17 in the silo during the operation of the silo unloader.
Referring to Figures 1, 2, and 4, control system 77 has a control box 78 mounted on silo ~all 11. Box 78 can be located in other accessible locations. A cable 79 containing suit-able electrical lines comlects control box 78 to motor 66.
A second cable 81 connects control box 78 to a control switch 82 mounted on frame 22. As shown in Figures 2 and 4~ control switch 82 has a box shaped housing 83 attached to a mount 84.
Mount 84 is attached to bar 23 with suitable fasteners, such as nut and bolt assemblies. Control switch 82 is an electrical ~ switch having a movable actuator or finger 86. Switch 82 ,~ is normally closed when actuator 86 is in a downwardly directed position as shown in Figure 4. Switch 82 is opened once dur-ing each revolution of unloader collector 18. As shown in Figure 2, an elongated generally horizontal arm 87 located above impeller housing 35 extends in the direction of collector 18. Nut and bolt assemblies 88 secure arm 87 to rotatable boot 38. Arm 87 moves in horizontal circumferential direction .~,j, ~.....

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as indicated by arrow 89 along with collector 18.
Referring to Figure 5, there is shown the electrical cir-cuit diagram or wiring diagram indicated generally at 90 for electrically coupling control switch 82 with the reversible electrical motor 66. The components of the electrical circuit are located in control box 78. A power supply 91 is connected across terminals 92B and 92C of the power supply input 92.
Power supply input may be a connector for receiving a three-prong electrical plug leading to the power supply. In the pre-ferred embodiment, the power supply is a conventional AC elec-; tric power source. A conductor 93 connects terminal 92A of plug 92 to ground. A pair of conductors 94 and 95 connect ter-minals 92B and 92C to terminals 96A and 96B, respectively, of a contactor indicated generally at 96. Contactor 96 has a coil 97 operative to control a pair of movable switching elements 98 and 99 which are connected to terminals 96A and 96B, respectively.
A conductor 101 connected to terminal 96A leads to an "auto-matic let-down switch" 102 and a "continuous switch" 103. Swit-ches 102 and 103 are manually operable normally open, single pole, single khrow switches. A conductor 104 connects the con-tact of switch 102 to one terminal of a light assembly 106 which indicates the "on" condition of the automatic let down control. A conductor 107 connected to the other terminal of light assembly 106 leads to a terminal 96C on contactor 96.
Terminal 96A is connected to one end of coil 97. The opposite end of coil 97 is connected to a conductor lOg leading to one switching terminal o~ an automatic time delay relay unit indi-` cated generally at 109.
A second light assembly 110 operative to indicate a motor "run" condition is connected by a conductor llOA to terminal96C.

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Automatic time delay relay unit 109 has a normally closed switching element 111 controlled by a relay coil 112. An adjust-able electronic time delay device 113 is connected in series with coil 112. Device 113 has a manually adjustable control knob 114. A conductor 115 connects switching element 111 to the contact of control switch 82. Switch 82 has a normally closed switching element 85 that is opened in response to a change in the position of actuator 86 once during each revolu-tion of the silo unloader. A conductor 116 connects time delay device 113 to line 115. The opposite end of coil 112 is con-nected with a conductor 117 to terminal 96B and to switching ` element 99, thereby providing power to coil 112. A conductor ; 120 connects conductor 117 to terminal 96C. The circuit to coil 112 is energized when switching element 85 of control switch 82 is closed, thereby opening the switching element 111.
A pair of conductors 118 and 119 are connected to the con-tacts for switch elements 98 and 99, respectively. Cable 79 contains the conductors 118, 119, 127, and 128 and 136. Switch element 99 of contactor 96 is connected by a conductor 121 to a manual reversing switch indicated generally at 122. Revers-ing switch 122 is a double pole, double throw switch and has a pair of movable switc]ling elements 123 and 124 and a manu-ally operated actuator 126. Motor 66 has electrical terminals .
66A, 66B, 66C, 66D, and 66E. A conductor 127 connects a first contact 130 to terminal 66C of motor 66. A second conductor 128 connects a second contact 131 to another terminal 66D of motor 66. Switching element 123 is movable to selectively en-gage contacts 130 and 131. Conductor 121 is connected to a contact 132. Conductor 127 is also connected to a contact 133. Contacts 132 and 133 are selectively engageable by swit-ching element 124. Switching element 123 is connected to the g ~/

~5~5 contact of switch element 98 by a conductor 129. Switching element 124 is connected to the conductor 128 which also con-nects to contact 131. Switch 122 is a two position swi.tch, selectively positioned in a ~irst position where switching ele-ments 123 and 12~ engage contacts 130 and 132, respectively, and a second position wherein switching elements 123 and 124 engage contacts 131 and 133, respectively. The circuit for the reversible electric motor 66 also includes a ground conductor 136 connected to terminal 66E.
The operation is as follows:
When continuous-run switch 103 is closed, power winch 49 is continuously operated by motor 66. Reversing switch 122 is used to determine the direction of rotation of motor 66.
When continuous run switch 103 is closed a circuit is completed for energizing coil 97 of contactor 96 thereby closing switches ~ 98 and 99. This circuit is from terminal 92B and through con-ductor 94, terminal 96A, conductor 101, switch 103, conductor ~` 105, terminal 96D, coil 97, terminal 96C, conductor 120, ter-minal 96B and conductor 95 to terminal 92C. When switch 98 is closed a circuit is completed through motor signal light assem-bly ll~ ~rom terminal 92B, conductor 94, terminal 96A, switch 98, conductor llOA, light llO, conductor llOB, terminal 96C, conductor 120, terminal 96B, and conductor 95 to terminal 92C.
~ Light assembly 110 will emit a light indicating that the cir-::~ cuit is complete and that motor 66 is continuously operating.
The motor run circuit is from terminal 92B, through switch 98 and conductor 118 to motor terminal 66B and from motor ter-minal 66A and through conductor 119 and switch 99 to terminal .~ 92C. The reversing circuit is from terminal 92B and switch 98, through conductor 129, switch 123 and conductor 127 to motor terminal 66C and from motor terminal 66D, through conductor .~

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128, switch 124, and conductor 121 and switch 99 to terminal 92C when reversing switch 122 is in the up position as shown.
When switch 122 is in the down position the circuit across motor terminals 66C and 66D is reversed. In this mode control switch 82 on unloader 17 is not used.
; The automatic let-down mode operates as follows. ~hen con-tinuous switch 103 is open and the automatic let-down switch 102 is closed, a circuit is completed from terminal 92B, through conductor 94, terminal 96A, conductor lOl, switch 102, conduc-; lO tor 104, light 106, conductor 107, terminal 96C, conductor 120, terminal 96B and conductor 95 to terminal 92C. A parallel cir-cuit extends from switch 102~ through conductor 104, control switch 82, conductor 115, switch 111 of relay 109, conductor ; 108, ~erminal 96D, coil 97, terminal 96C, conductor 120, ter-minal 96B and conductor 95 to terminal 92C. Another parallel circuit extends Erom switch 82, through conductor llS, conduc-tor 116, time delay device 113, coil 112, conductor 117, ter-; minal 96B and conductor 95 to terminal 92C. Control switch 82 `~ is normally closed as is relay 109. When a circuit is completed 20 across time delay device 113 and coil 112, coil 112 is energized and switch lll opened only after a time delay determined by the adjustment of member 11~. In an actual em~odiment, this time delay can be adjusted from approximately one second ~o three minutes. Thus, any time that the automatic let-down switch 102 is closed, winch motor 66 will run until the time delay relay 112 opens the circuit. Thereafter, each time that control switch 82 is opened in response to a revolution of un~
loader collector 18~ the time delay relay 112 closes switching element 111 energizing contactor coil 97 and thus operating 30 motor 66. Motor 66 is energized through reversing switch 122 so that its direction of operation will depend upon the position . .

of the reversing switch elements 123 and 124.
The time delay relay 112 has a relatively short reset timed so any time the circuit to it is broken (even if only a moment-ary interruption) it will reset and close. Control switch 82 ; with its elongated actuator 86 will remain open between 10 to 15 seconds of each revolution of the unloader collector 18. ~ctu-ator 86 must move over moving arm 87 which holds switch element 85 in the open position for a short period of time. Any moment-ary break in the circuit will reset timed delay relay 109. Re-lay 109 is adjusted by electronic time delay device 113. The adjustment can be from approximately one second to up to three minutes or more. This controls the duration of the operation of motor 66. Wlth switch 122 in the "down position", unloader 17 wi~l be lowered a predetermined amount during each revolution of the unloader collector 18 in the silo. The amount of lowering of unloader 17 is easily adjusted by adjusting time delay device 113. Control knob 114, being part of time delay device 113, provides for easy manual adjustment of the time delay and there-by the lowering time per revolution of the unloader in the silo.
2a While there has been shown and described a preferred em-bodiment of the invent.ion, it is understood that changes in the structure and electrical circuit and components can be made by .~; those skilIed in the art without departing from the invention.
The invention is defined in the followina Claims.

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Claims (52)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In combination, a silo unloader operable to remove material from a tower silo, said unloader having a material collector and means for discharging material from the silo, said silo unloader including a rotatable portion, winch means having an electric motor, a cable connecting the winch means and silo unloader whereby on operation of the motor the silo unloader is vertically moved in the silo, means suspending the cable from the upper portion of the silo, and control means electrically connected to the electric motor for con-trolling its operation thereby controlling the position of the silo unloader in the silo, said control means having a control switch non-rotatably mounted with respect to the silo unloader, said switch having an actuator operably engageable by the rotatable portion of the silo unloader once during each revolution of the rotatable portion to trigger the con-trol switch, and means connected to the switch for operating the electric motor each time the actuator triggers the con-trol switch.

2. The structure of Claim 1 wherein: the means connected to the switch includes a switching element connected in series with the control switch, a relay coil operable to open the switching element, and delay means connected to the relay coil for delaying the switching of the switching element whereby the electric motor is operated only a limited period of time each time the actuator triggers the control switch.

3. The structure of Claim 2 including: means to adjust the delay means for varying the delay time of the relay coil, and thereby the run time of the motor.

4. The structure of Claim 1 wherein: the control means includes a motor reversing switch connected to the winch motor whereby the winch motor is selectively operated in opposite directions.

5. The structure of Claim 1 wherein: said rotatable por-tion includes an arm engageable with the actuator once during each revolution of the collector.

6. The structure of Claim 1 wherein: the silo unloader has a non-rotating portion including a frame connected to the cable, said control switch being mounted on the frame.

7. The structure of Claim 6 wherein: said rotatable por-tion includes an arm located below said frame, said arm engage-able with the actuator once during each revolution of the col-lector.

8. The structure of Claim 1 wherein: said control switch has a normally closed switching element that is opened in response to movement of the actuator.

9. The structure of Claim 1 wherein: the control means includes first on-off switch means connected in series with the control switch means to connect the control switch means to a power source, and a second on-off switch means operable to continuously connect the winch motor to a power source.

10. The structure of Claim 1 wherein: the control means includes contactor means having switching means operable to connect a power source to the winch motor, and a relay coil operable to control the switching means, said coil being con-nected to a time delay means to control the operation of the relay coil.

11. In combination, a silo unloader operable to remove material from a tower silo, said unloader having rotatable means for collecting material in the silo and discharging the material from the silo, non-rotatable means operatively connected to the rotatable means, winch means having an electric motor, cable means connecting the winch means with the non-rotatable means of the silo unloader whereby on opera-tion of the motor the silo unloader is vertically moved in the silo, means suspending the cable means in the silo, and control means electrically connected to the motor for controll-ing its operation thereby controlling the position of the silo unloader in the silo, said control means having first means operable to supply electric power to the motor for a limited period of time, and control switch means mountable on the non-rotating means of the silo unloader and electrically coupled to the first means, said switch means having actuator means operably engageable with a portion of the rotating means of the silo unloader during each revolution of said rotatable means to trigger the first means thereby operating the motor for a limited period of time to lower the silo unloader in the silo.

12. The structure of Claim 11 wherein: the portion of the non-rotatable means includes an arm engageable with the actuator once during each revolution of the rotatable means.

13. The structure of Claim 11 wherein: the non-rotatable means includes a frame connected to the cable means, said control switch means being mounted on the frame.

14. The structure of Claim 13 wherein: said portion of the non-rotatable means includes an arm located below said frame, said arm being engageable with the actuator of the con-trol switch means once during each revolution of the rotat-able means of the silo unloader.

15. The structure of Claim 11 wherein: said control switch means has a normally closed switching element that is open in response to movement of the actuator.

16. The structure of Claim 11 wherein: said first means includes time delay means having a switching element connected in series with the switch means, a relay coil operable to open the switching element, and a delay means connected to the relay coil for delaying the switching of the switching element.

17. The structure of Claim 16 including: means to adjust the delay means for varying the delay time of the relay coil.

18. The control of Claim 11 including: a loader revers-ing switch adapted to be connected to the motor of the winch operable to selectively operate the motor in opposite direc-tions.

19. The control of Claim 11 including: first on-off switch means connected in series with the control switch means to connect the control switch means to a power source 9 second on-off switch means operable to continuously connect the winch motor to a power source whereby the winch motor con-tinuously operates as long as the second on-off switch means is on.

20. The structure of Claim 11 including: contactor means having switching means operable to connect a power source to the motor of the winch, and a relay coil operable to con-trol the switching means, said relay coil being connected to the first means.

21. The structure of Claim 11 wherein: said first means includes contactor means having first switching means operable to connect a power source to the motor of the winch and a first relay coil operable to control the first switching means, time delay means having a second switching means connected in series with the first switch means, a second relay coil operable to open the second switching means, and a delay means electrically connected to the second relay coil for delaying the switching of the second switching means, and first on-off switch means connected in series with the control switch means to connect the control switch means to a power source and thereby connect the time delay means to a power source, and a second on-off switch means connected to the first relay coil, said second switch means when in the on position functioning to continu-ously connect the winch motor to a power source whereby the winch motor continuously operates along a second switch means in the on position.

22. The structure of Claim 21 including: means to adjust the delay means for varying the delay time of the second relay coil thereby varying the operating time of the motor of the winch.

23. The structure of Claim 21 including: a motor revers-ing switch connected to the motor of the winch and the first switching means operable to selectively cause the motor to operate in opposite directions.

24. A let-down control for controlling the position of a silo unloader in a tower silo with a winch connected to the silo unloader by a cable, said winch having a motor, said silo unloader having a rotatable portion, comprising: first means operable to supply electric power to the motor for a limited period of time, control switch means non-rotatably mounted with respect to the silo unloader and electrically connected to the first means, said switch means having an actuator disposed in the path of and operably engageable by the rotatable portion of the silo unloader once during each revolution of said rotatable portion thereby to trigger the control switch means, and means connected to said control switch means for operating said winch motor for a limited period of time to lower the silo unloader each time said actuator triggers the control switch means, the first means thereby causing the motor to operate.

25. The control of Claim 24 wherein: said first means includes time delay means having a switching element connected in series with the switch means, a relay coil operable to open the switching element, and delay means electrically connected to the relay coil for delaying the switching of the switching element.

26. The control of Claim 25 including: means to adjust the delay means for varying the delay time of the relay coil.

27. The control of Claim 24 including: a motor revers-ing switch adapted to be connected to winch motor operable to selectively cause the motor to operate in opposite direc-tions.

28. The control of Claim 24 including: first on-off switch means connected in series with the control switch means to connect the control switch means to a power source, and a second on-off switch means operable to continuously connect the winch motor to a power source.

29. The control of Claim 24 including: contactor means having switching means operable to connect a power source to the winch motor, and a relay coil operable to control the switching means, said relay coil being connected to the first means.

30. The control of Claim 24 wherein: said first means includes contactor means having first switching means operable to connect a power source to the winch motor and a first relay coil operable to control the switching means, time delay means having a second switching means connected in series with the switch means, a second relay coil operable to open the second switching means, and delay means electrically connected to the second relay coil for delaying the switching of the second switching means, and first on-off switch means connected in series with the control switch means to connect the control switch means to a power source and thereby connect the time delay means to a power source, and a second on-off switch means connected to the first relay coil, said second switch means when in the on position functioning to continuously connect the motor of the winch to a power source whereby the winch motor continuously operates along a second switch means in the on position.

31. The control of Claim 30 including: means to adjust the time delay means for varying the delay time of the second relay coil thereby varying the operating time of the motor of the winch.

32. The control of Claim 30 including: a motor revers-ing switch connected to the motor of the winch and the first switching elements operable to selectively cause the motor to operate in opposite directions.

33. In combination, a silo unloader operable to remove material from a tower silo, said unloader including a portion rotatable within the silo, winch means having a driving motor and elongated flexible support means connecting the winch means and silo unloader whereby on operation of the motor the silo unloader is vertically moved in the silo, and control means operably connected to the motor and controlling the supply of motive power thereto for controlling its operation thereby controlling the position of the silo unloader in the silo, said control means having a control member non-rotatably mounted with respect to the silo unloader, said control member having an actuator operably engageable by the rotatable portion of the silo unloader once during each revolution of the rotatable portion to trigger the control member, and means connected to the control member for supplying motive power to motor each time the actuator triggers the control member.

34. The structure of Claim 33 wherein: the means con-nected to the control member includes a switching element connected in series with the control member, a relay coil operable to open the switching element, and a delay means connected to the relay coil for delaying the switching of the switching element whereby the electric motor is operated only a limited period of time each time the actuator triggers the control member.

35. The structure of Claim 34 including: means to adjust the delay means for varying the delay time of the relay coil, and thereby the run time of the motor.

36. The structure of Claim 33 wherein: the control means includes a motor reversing switch connected to the winch motor whereby the winch motor is selectively operated in opposite directions.

37. The structure of Claim 33 wherein: said rotatable por-tion includes an arm engageable with the actuator once during each revolution of the collector.

38. The structure of Claim 33 wherein: the silo unloader has a non-rotating portion including a frame connected to the cable, said control switch being mounted on the frame.

39. The structure of Claim 38 wherein: said rotatable por-tion includes an arm located below said frame, said arm engage-able with the actuator once during each revolution of the col-lector.

40. The structure of Claim 33 wherein: said control switch has a normally closed switching element that is opened in response to movement of the actuator.

41. The structure of Claim 33 wherein: the control means includes first on-off switch means connected in series with the control switch means to connect the control switch means to a power source, and a second on-off switch means operable to continuously connect the winch motor to a power source.

42. The structure of Claim 33 wherein: the control means includes contactor means having switching means operable to connect a power source to the winch motor, and a relay coil operable to control the switching means, said coil being con-nected to a time delay means to control the operation of the relay coil.

43. In a silo unloader operable to remove material from a tower silo, said unloader having a material collector and means for discharging material therefrom, said silo unloader including a portion rotatable within the silo and means for rotating the same, winch means having an electric motor, a cable connecting the winch means and silo unloader, means suspending the cable from the upper portion of the silo where-by upon operation of the motor the silo unloader is vertically moved in the silo, and control means electrically connected to the electric motor for controlling its operation and there-by the vertical position of the silo unloader in the silo, the improvement wherein said control means includes a control switch non-rotatably mounted with respect to the silo unloader, said switch having an actuator disposed in the path of and operably engageable by the rotatable portion of the silo unloader once during each revolution of said rotatable portion thereby to trigger the control switch, and means connected to said switch for operating said electric winch motor for a limited period of time to lower the silo unloader each time the said switch actuator triggers the control switch.

44. The improved silo unloader of Claim 43 wherein: the means connected to the switch includes a switching element connected in series with the control switch, a relay coil operable to open the switching element, and delay means con-nected to the relay coil for delaying the switching of the switching element whereby the electric motor is operated only a limited period of time each time the actuator triggers the control switch.

45. The improved silo unloader of Claim 44 including:
means to adjust the delay means for varying the delay time of the relay coil, and thereby the run time of the motor.

46. The improved silo unloader of Claim 43 wherein: the control means includes a motor reversing switch connected to the electric motor whereby the electric motor is selectively operated in opposite directions.

47. The improved silo unloader of Claim 43 wherein: said rotatable portion includes an arm engageable with the actuator once during each revolution of the collector.

48. The improved silo unloader of Claim 43 wherein: the silo unloader has a non-rotating portion including a frame connected to the cable, said control switch being mounted on the frame.

49. The improved silo unloader of Claim 48 wherein: said rotatable portion includes an arm located below said frame, said arm engageable with the actuator once during each revolu-tion of the collector.

50. The improved silo unloader of Claim 43 wherein: said control switch has a normally closed switching element that is opened in response to movement of the actuator.

51. The improved silo unloader of Claim 43 wherein: the control means includes first on-off switch means connected in series with the control switch to connect the control switch to a power source, and a second on-off switch means operable to continuously connect the electric motor to a power source.

52. The improved silo unloader of Claim 43 wherein: the control means includes contactor means having switching means operable to connect a power source to the electric motor, and a relay coil operable to control the switching means, said coil being connected to a time delay means to control the opera-tion of the relay coil.