US2555880A - Safety device - Google Patents

Description

June 1951 w. J. FRUECHTEL 2,555,880

SAFETY DEVICE Filed May 11, 1945 2 Sheets-Sheet 1 I I7 I K 19- INVENTOR.

W lLBERT J. FREUCHTEL BY ATTORNEYS June 5, 1951 w. J. FRUECHTEL 2,555,880

SAFETY DEVICE Filed May 11, 1945 2 Sheets-Sheet 2 INVENTOR.

WILBERT J. FREUCHTEIL M CV'WM.

ATTORNEYS Patented June 5, 1951 UNITED STATES PATENT OFFICE! SAFETY DEVICE Wilbert J. Fruechtel, Cleveland, Ohio, assignor to The C. 0. Bartlett & Snow Company, Cleveland, Ohio, a corporation of Ohio Application May 11, 1945, Serial No. 593,238

6 Claims. 1 This invention relates as indicated to safety devices and more especially to such devices -which may be used in conjuction with endless conveyors.

The common form of endless conveyor is usually driven by means of an electric motor acting through a speed reducing device, which latter device is connected to the conveyor by a belt or chain driving connection. Since there is always a possibility of a foreign object becoming lodged in the conveyor mechanism,

some means should be provided to deenergize the driving means when the resistance to driving the conveyor reaches a predetermined value so as to prevent damage to the conveyor parts when such breaking or other derangement of the conveyor occurs.

' Heretofore, it has been the practice to provide a metal shear pin in the driving means for the conveyor so that such pin will shear off under a predetermined load to disconnect the driving means from the conveyor. Shear pins, however accurately produced, are inclined to vary' in their breaking loads and when a shear pin has once broken, there is a strong tendency on the part of workmen to insert a rigid pin in its place, thus eliminating all safety provision.

It is a principal object of my invention to provide a safety device which is more positive and sensitive in its reaction to overloads than 'such shear pins as have been previously used and, likewise, more sensitive than conventional overload relays which have been used on cc casion in the power line to the motor.

It is a further and more particular object of my invention to provide a safety device of the character described which is relatively inexpensive and which cannot be readily tampered with;

Other objects of my invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain ilustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawings:

Fig. 1 is a fragmentary side elevational view of a conveyor provided with driving means incorporating the safety device of my invention;

Fig. 2 is a fragmentary view of the apparatus 'the base v thereon may rotate in a clockwise directiorifas viewed in Fig. 1, about theaxis of the pin ll.

ings and more especially to Fig. 1, the conveyor here illustrated for purposes of convenience in describing my invention comprises spaced sprockets generally indicated at l and 2 about which is trained an endless conveyor belt 3 of conventional design, and forming no part of this invention. The conveyor which may be thus of any standard form of construction is driven through the medium 'of a non-slipping web, generally indicated at 4 and which usually consists of an endless chain trained about a sprocket 5 on the conveyor and a corresponding sprocket 6 on a speed reducing device 1 which isdriven by means of an electric motor 8.

Positioned adjacent the conveyor is a: supporting frame generally indicated at 9, on which there is mounted a base It] which carries the speed reducing device I and the motor 8.

The base I0 is pivotally secured to its supporting frame by means of a pivot pin I I so that II] and the mechanism supported Mounted on theframework 9 beneath the base l0, and as most clearly illustrated in enlarged' Figs. 2 and 3, is a switch box l2 having a projecting switch actuating handle l3 adapted to be actuated by a cam member I4 connected .to and extending downwardly from the base II].

The switch I2 may be of any well-known construction and will be connected in the control circuit for the power line leading to the motor 8 in the manner illustrated, for example, in Fig.

In Fig. 4, the power lines to the motor 8 are shown at l5 and I6. In the line Hi there is the main switch I! controlled by means of a relay l8 energized by the control circuit. The control circuit consists of leads l9 and 20 across which the relay I8 is adapted to be connected by means of a switch 2| actuated by a control relay 22. The relay 22 is connected across the lines l9 and 20 by means of leads 23 and 24 in series with which are switches I2 and 25.

The relay 22 may be connected to the control circuit lead 20 by means of a lead 26 in series with which is a starting switch 21. The operation of the circuit illustrated in Fig. 4 is briefly as follows.

When the; parts are in the position, illustrated in Fig. 4, i. e. the conveyor is not in operation, the main switch I! will be open, likewise, the switch 2| in the control circuit. The operator then closes the normally open start switch 21" :which will energize the relay 22 by connecting. it across the lines l9 and 2B. Energization of the relay 22 will close the switch 2| and thereafter the operator may open the start switch 2.! and the relay 22 will keep the switch 2! closed; because of the back contact lead 24 through normally closed stop switch 2-5 and the normally closed limit switch [-2.

When now there issome obstruction to. thenormal. movement oi. the endless conveyor 3, continued operation of the motor 8 willv result in the sprocket 6, crawling, toward the conveyor. on

the tight side. of the non-slipping webv or chain switch arm i3v from its full line. position, as.

illustrated in Fig. 2,, to. its dotted linepositioni'. e. it will open. the. normally closed switch 12...

Since during the. normal continuous, opera.- tion. of the conveyor the. start, switch 2.! is open, opening the. limit switch 1.2, will. deenergi-ze. the relay 22,, opening the switch 2.I., resulting in deenergizing, the relay l8, opening. the. witch I! and stopping the motor 8...

Even though thebase lilshould. later settle back down, onits supporting framework, permitthe. switch [2 toclo'se, the conveyor would not.- start. because of the normally open. control switch 2i and thus. before. the. conveyor can be started again, itis necessary for the operator to closethe start button 21..

Instead of having the driver means, i. e.. the

motor 8- and. speed reducer I mounted on a base such. as, I; which. is. pivotally supported to oscillate. in a, vertical. plane, it. may be convenient in certain instances to have the basev such as, 2.8.Fig. carrying the, motor 8 and the speed reducer l oscillate. in. a. horizontal. plane, by having, the same pivotally secured to. vertically extending shaft or pin. 29; on the, fixed support 28c. It will. be. observed that when an. arrangement such.- as illustrated in. Fig. 1 is, employed, the weight of the base. [0, and the mechanism supported thereby maintains the,- parts in their normal. relation; however, when an expedient. such as, is. illustrated in Fig... 5. is. employed, a spring such. as that illustrated. at. 3.0; may be utilized for a, corresponding purpose, i.. e.., for the. purpose of maintaining. the. base 28 in proper location. by urging the same against. a fixed. stop 3.1.. 'A limit switch, generally mdicatled at. {211. in Fig... 5. extending, forinstance, through an opening in the fixed support 28a and constructed, and. operable similar to that of switch, 12 previously illustrated and described, may be employed for a. similar function. i

In its. general aspects, the drive. de-energizin means, while illustrated bya switch as aforeindicated, may be. of. other forms accomplishing the action (with electrical operationv or wholly mechanical unclutching operation), as set ofiE by displacement of the drive means from its normal operating position. 7

While the invention has been illustrated and described in connection with an endless conveyor, its application to other types of equipment where similar problems are encountered will be apparent tothose familiar withthe art.

Other modes of applying; the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

I therefore particularly point out and distinct- 1y claim as my invention:

1;.111 a conveyor provided with a non-slipping drive, a prime mover for actuating said nonsl'ipping drive, and control means including a movable base supporting said prime mover mounted to swing horizontally when the driving re sistance to said non-slipping drive exceeds a pre-' determined value, means responsive to such movement. of said base for deenergizing said nonslipping drive, and means tending to swing said base. back to its normal position.

2.. Ina conveyor provided with an endless nonslippi'ng. web, means for driving said conveyor comprising a prime mover, a, driver member ac.- tuated by said prime mover and about which said nonrslipping, web is trained, a. movable base. supporting said prime mover, said base being pivoted to, swing in. a horizontal plane with said driver member relatively to said conveyor when the resistance. to. movement by said non-slipping web exceeds a. predetermined value, means responsive to. such movement of said base for deenergizing said' prime mover, and means tending to swing said movable base back to its original positioIn 3.. In. a conveyor provided with an endless nonsli'pping web, means for driving said conveyor comprising a, prime. mover, a driver member ac tuatedi by said prime mover and about which said non-slipping web is trained, a fixed support, a movable base thereon supporting said prime r mover, said base being pivoted to swing in a horizontal plane with said. driver member reliatively to said conveyor when the. resistance to movement by said non-slipping, web exceeds a predetermined value, means on said fixed support in the path. of. such. movement of said base adapted to. be tripped in swinging movement of said base. to deenergize said prime. mover,, and means tending. to swing. said movable base back to its original position.

1.111 a. conveyor provided with. an endless nonslipping, driving web, a. pivotally mounted base on which is driving means comprising a. motor and a sprocket wheel about which said non.- slippingv web. is. trained, said base pivoted so. as to move with said driver means. relatively to said conveyor when the resistance tov movement.- by said non-slipping web. exceeds av predetermined value, and means for stopping the drive motor consisting. of. circuit breaker means. including, an initial stop control, switch operated by such movement of said base, and a relay switch in circuit with said control switch. and deenergi'zed by the the operation thereof.

5.111 a conveyor provided with an endless chain drive, a driving unit for. said conveyor comprising a motor,,a speed reducer and a sprocket aboutv which. said endless chain is trained, a. base. carrying- Said driving. unit, means. movably support-- ing said base; whereby it. may move relatively toward said conveyor as the resistance to move ment by said endless chain exceeds a predetermined value, and means for stopping the drive motor shaft consisting of circuit breaker means including an initial stop control switch operated by such movement of said base, a relay switch and an electrically operated motor feed switch both in circuit with said control switch and deenergized by the operation thereof, and a starting switch in another circuit in series with said relay switch.

6. In a conveyor provided with an endless chain drive, a driving unit for said conveyor comprising a motor, a speed reducer and a sprocket about which said endless chain is trained, a base carrying said driving unit, means supporting said base whereby it may swing horizontally relatively to said conveyor as the resistance to movement by said endless chain exceeds a predetermined value, and means for stopping the drive motor shaft consisting of circuit breaker means including an initial stop switch in the path of such movement of said base, a relay switch and an electrically operated motor feed switch in circuit with said control switch and decnergized by the operation thereof, and a starting switch in another circuit in series with said relay switch.

WILBERT J. FRUECHTEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,398,790 Ogur Nov. 29, 1921 2,022,007 Moore Nov.. 26, 1935 2,082,052 Frost et a1. June 1, 1937

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