US2873848A

US2873848A - Shaft locking means

Info

Publication number: US2873848A
Application number: US567160A
Authority: US
Inventors: Walter C Steinmetz
Original assignee: Jeffrey Manufacturing Co
Current assignee: Jeffrey Manufacturing Co
Priority date: 1956-02-23
Filing date: 1956-02-23
Publication date: 1959-02-17
Anticipated expiration: 1976-02-17

Description

Feb. 17, 1959 w. c. STEINMETZ 2,873,848

SHAFT LOCKING MEANS v Filed Feb. 25, 1956 2 Sheets-Sheet 1 {7 INVENTOR},

l v WALTEE C. STEINMETZ) ATV-Y Feb. 17, 1959 w; c. STEINMETZ 2,873,848

SHAFT LOCKING MEANS Filed Feb. 25, 1956 2 Sheets-Sheet 2 J I 'l 4: 1 1

START MOTOR STARTING 5T0 CIRCUIT Fly. 4

INVENTOR; WALT ESE C STEsNM ETZ/ /4& //4%,

United States Patent SHAFT LOCKING MEANS Walter C. Steinmetz, Columbus, Ohio, assignor to lzhe Jeffrey Manufacturing Company, a corporation of 01110 Application February 23, 1956, Serial No. 567,160

20 Claims. (Cl. 198232) The instant invention relates to conveyors, and more particularly to a novel means for preventing rearward rotation of a shaft in aconveyor.

It is the prime object of the instant invention to provide a novel means for locking a shaft and preventing rotation thereof.

It is a further object of the instant invention to provide means to prevent rearward rotation of a conveyor head shaft and thereby prevent rearward movement of the conveying means.

It is another object of the instant invention to provide a locking means for a head shaft of a conveyor, which locking means is automatically released when the conveyor power means is energized to start rotation of the shaft.

It is another object of the instant invention to provide a locking means for a conveyor head shaft in which the locking means is automatically released when the conveyor driving means is energized to start rotation of the shaft, and including speed responsive means connected to the shaft which is operative to render the locking means effective to lock the shaft when the latter loses speed and stops.

It is still another object of the instant invention to provide a locking means to prevent rotation of a shaft, in which there is provided a control circuit which is energized by the release of the locking means in response to the initial rotation of the shaft, the locking meansbeing operative to energize the control circuit for actuating means for holding the lockingmeans in released position while the shaft continues its rotation.

A further object of the instant invention is to provide a locking means to prevent rearward rotation of a shaft, in which the shaft is provided with a ratchet wheel and the locking means comprises a pawl for engaging the ratchet wheel to lock the shaft and thereby prevent rearward rotation of the shaft, the pawl being released by forward rotation of the shaft and operating means for holding the pawl in released position to permit continued rotation of the shaft in a forward direction. 7

Still another object of this invention is to provide a novel locking means for a shaft in which the shaft is provided with a ratchet wheel and the locking means comprises a pawl adapted to engage the ratchet wheel to lock the shaft against rotation in a rearward direction,- forward rotation of the ratchet wheel releasing the pawl from engagement therewith and there being provided means for holding the pawl. in released position, which means is included in a control circuit which is energized by the pawl upon release thereof to actuate the holding means for retaining the pawl in released position.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

In the accompanying drawings:

Fig. .1 is a partial elevational view showing the head shaft of a conveyor which includes a novel means for preventing rotation of the shaft;

Fig. 2 is an elevational view in section showing the novel shaft locking means of this invention;

Fig. 3, is a plan view in section of the novel shaft locking means taken on the line 33 in Fig. 2;

Fig. 4 is a circuit diagram showing the control. circuit for the novel shaft locking means and its association with the power circuit; and

Fig. 5 is a circuit diagram showing a modification of the control circuit illustrated in Fig. 4.

Referring to Fig. 1 of the drawings, there is shown a conveyor N of the vertical elevator type comprising a platform 11 which supports the head shaft 12 of the conveyor 10. The platform 11 also supports a power drive means 13 on a laterally extending portion thereof, which may be in the form of an electric motor or the like motive means. The power drive means 13 includes a pulley or wheel 14 on which there is entrained a power transmitting chain 15 which drives a pulley or wheel 16 secured on the shaft 12. The wheel 16 is secured to the shaft 12 and transmits power to the shaft 12 for driving the conveyor.

The conveyor 10 has an endless chain 17 which is entrained about a sprocket wheel 18 secured to the shaft 12. The endless chain 17 is also entrained about a second sprocket wheel at the opposite lower end of the conveyor If) (not shown). The chain 17 includes a plurality of buckets 19 each secured to a link thereof, which buckets rise on the right side of the conveyor to convey material to the top thereof, and the buckets 19, as they pass around the periphery of the sprocket wheel 18, discharge their contents into a chute or like means and descend in inverted position on the left side of the conveyor as seen in Fig. 1.

It is apparent that the buckets 19 on the right side of the conveyor. are loaded with material whereas the buckets on the left side of the conveyor are empty, so that the added weight on the right side of the conveyor would normally cause the chain 17 to move in a clockwise or rearward direction on the sprocket wheel 18 unless the power drive means 13 is operating to move the conveyor chain 17 in a direction to raise the loaded buckets 19 or if some other means is provided to prevent clockwise or rearward rotation of the shaft 12 when the power drive means 13 is inoperative. The instant invention contemplates the provision of a novel locking means adapted to cooperate with shaft 12 to lock the shaft against rearward rotation and prevent downward movement of the loaded buckets 1% when the power drive means 13 is not operative to drive the shaft 12.

The novel locking means of this invention includes a ratchet wheel 20 secured to the shaft 12 and adapted to rotate therewith in a counterclockwise or forward direction when the power drive means 13 is operative. The teeth 21 on the ratchet wheel 20 face rearwardly and are adapted to be engaged by a pawl 22 to prevent clockwise or rearward rotation of the ratchet wheel 20 and the shaft 12. As will appear hereinafter, when the power drive means is inoperative the pawl 22 projects into the path of the ratchet wheel periphery and engages with a tooth 21 thereof to prevent clockwise or rearward rotation, and resists the force applied by the loaded buckets 19 attempting to rotate the shaft 12 in a rearward direction.

The pawl 22 is contained within a housing 23 which is supported on the platform 11. The housing 23 includes a base plate 24 provided at its forward end with a pair of posts 25 disposed one at each side of the base plate 24. Each of the posts 25 is bored for the reception of the opposite ends of a transversely extending pin 26, which is fixedly secured to the posts 25 by set screws 27.

The pawl 22 is bored transversely through the bottom thereof and receives therein the intermediate portion of the pin 26 which spans the space between the posts 25.

The pawl 22 pivots on the pin 26 between a position in which it is in engagement with a ratchet wheel tooth 21 as seen in Fig. 2, and a position in which the pawl 22 iswithdrawn into the housing 23 and is held in released position out of engagement with the teeth 21 of the ratchet wheel 20 (as seen in broken lines in Fig. 2) thereby permitting free rotation of the shaft 12.

A central portion 28 of the bottom of the pawl surrounding the pin 26 is cut away to provide space for a torsion spring 29 which is wound on the pin 26. One arm 30 of the torsion spring 29 is fixedly secured to the base plate 24 and a second arm 31 abuts a shoulder 42 on the pawl 22, the force of the spring operating to urge the pawl 22 into engagement with a tooth 21 'of the ratchet wheel 20. When the power drive means 13 is inoperative the pawl 22 is urged into engagement with a tooth 21 of the ratchet wheel 20 by the torsion spring 29. When the power drive means 13 is energized to operate the conveyor and rotate the shaft 12 in a forward direction. The electric control circuit includes a I.

switch 35 which may be a normally open micro-switch which is closed to energize the control circuit.

The housing 23, which contains the locking mechanism, has a front wall 36 and an intermediate wall 37 formed with

apertures

38 and 39, respectively. A plunger 40 is seated in the

apertures

38, 39 and extends between the actuator 41 of the switch 35 and a shoulder 42 on the pawl 22, located adjacent the cut away portion 28 of the pawl. Thus, when the pawl is pushed away from engagement with a ratchet tooth 21 upon forward rotation of the ratchet wheel 20 and the shaft 12, the shoulder 42 abuts the plunger 40 pushing it rearwardly in the

apertures

38, 39 and operating the switch actuator 41 to close the switch 35 and thereby energize the control circuit for a purpose to be explained hereinafter.

- I The rear face of the pawl 22 is formed with a cutout pocket 45 facing rearwardly in the locking mechanism housing 23. One end of a connecting link 46 is disposed within the pocket 45 and secured to the pawl 22 by a pin 47. The connecting link 46 extends rearwardly from the pawl 22 through an aperture 48 in the front wall 36 and at its rear end is connected to an armature 49 of a solenoid 50 which is bolted to the rear wall 52 of the housing 23. The front end of the armature 49 is bifurcated for the reception of the rear end of the connecting link 46. A stud 51 extends between the legs of the bifurcated portion of the armature 49 and through the end of the connecting link 46 thereby connecting the armature 49 to the pawl 22.

When the pawl 22 is in engagement with a tooth 21 ofv the ratchet wheel 20, as illustrated in Fig. 2, the switch 35 is open and the solenoid 50 is dormant. When the power drive means 13 is energized, the shaft 12 and the ratchet wheel 20 start rotating in a counterclockwise and forward direction pushing the pawl 22 away from the teeth 21, thereby releasing the pawl. The shoulder 42 onthe pawl 22 pushes the plunger 40 rearwardly to close the switch 35 thereby energizing .the control circuit and the solenoid 50, the latter drawing the armature 49 rearwardly to pull the pawl 22 completely away from the teeth 21 of the ratchet wheel 20, and as long as the control circuit 55 remains energized, the solenoid 50 is operative to hold the locking mechanism in released position to permit free rotation of the shaft 12.

The control circuit is illustrated in Fig. 4, showing its connection with the power circuit for the power drive means Energy is delivered to the power drive means 13 through a plurality of power lines 53 connected through a conventional motor starting means 54. The locking mechanism control circuit 55 is connected across two of the lines 53. It is seen in Fig. 4 that the solenoid 50 and the switch 35 are connected in series in the control circuit.

When the power drive means is inoperative and no power is fed through the lines 53 the control circuit 55 is likewise not energized, and since the solenoid 50 is dormant, the pawl 22 is maintained in its forward position in engagementwith a tooth 21 of the ratchet wheel 20 by the force of the torsion spring 29, operating thereon. When the power drive means 13 is energized the shaft 12 and the ratchetwheel 20 start rotating, releasing the pawl 22 from engagement with the tooth 21 and closing the switch 35 to energize the control circuit 55 and the solenoid 50 for holding the pawl 22 in released position while the shaft 12 is rotating in'the forward or counterclockwise direction.

In a modified. form of the invention (see Fig. 5), the line 56 (Fig. 4) in the control circuit 55 is replaced by the line 57, which includes a speed responsive plugging switch 58 connected in series to the switch 35 and the solenoid 50. Referring to Fig. l, the switch 58 is seen to be connected to a pulley 59 secured on the shaft 12. A drive chain 60 is entrained on the pulley 59 and on a smaller wheel 61, which is a part of the plugging switch 58, to drive the latter. Thus, the plugging switch 58 is operated under control of the speed of the shaft 12. The plugging switch 58 may be of a conventional form which is speed responsive, to maintain the switch contacts closed when rotating above a given rotational speed.

: In operation the plugging switch 58 is normally open maintaining the control circuit 55 de-energized. After the shaft 12 has reached a given speed of rotation which is reflected in the rotational speed of the plugging switch 58, the contacts of the plugging switch 58 will close, thereby permitting the control circuit 55 to thereafter operate in response to the position of the pawl 22 as previously described.

The instant invention provides a novel locking mechanism to prevent rotation of a shaft in one direction, in which rotation of the shaft in the opposite direction releases the locking mechanism and thereby causes the energization of a control circuit to operate means for holding the locking means in released position while the shaft continues its rotation in the one direction. The control circuit for the novel locking mechanism is tied to the power drive means for the shaft, so that when the power drive means is deactivated the control means is likewise de-energized, whereupon the locking means again operates to lock the shaft against rotation in said opposite direction while the power drive means is inactive. As a further feature, the control circuit for the locking mechanism may include a Speed responsive plugging switch which is driven by the shaft, and operates the control circuit for holding the locking means in released position only when the shaft rotates above a given speed. The plugging switch constitutes a safety feature in that should the drive from the power drive means to the shaft fail accidentally, the shaft will lose speed and eventually stop rotating, whereupon the plugging switch will open and render the control circuit of the locking mechanism inoperative to hold the locking means in released position, so that the latter will again lock the shaft to prevent rotation thereof in said opposite direction until the shaft is again rotated in the one direction under control of the power drive means.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended, and applicant therefore wishes not to be restricted to the precise con-v sjtruction herein disclosed.

Having thus described and shown an embodiment of the invention, what it is desired to secure by Letters Patent of the United States is:

1. In combination with a shaft and power means for rotating the shaft in one direction, means for locking the shaft to prevent rotation thereof in the opposite direction, means operating in response to rotation of the shaft in the one direction for releasing the locking means, and means operative under control of the locking means for holding the locking means in released position while the shaft is rotating in the one direction.

2. In combination with a shaft and power means for rotating the shaft in one direction, means for locking the shaft to prevent rotation thereof in the opposite direction, means operating in response to rotation of the shaft in the one direction for releasing the locking means, means for holding the locking means in released position while the shaft is rotating in the one direction, control means operated by the locking means, and means for operating said holding means in response to the operation of the control means by the locking means.

3. In combination with a shaft and power means for rotating the shaft in one direction, means including a pawl for locking the shaft to prevent rotation in the opposite direction, said shaft including means engaged by the pawl and operating in response to rotation of the shaft in the one direction to release the pawl from engagement therewith, means for holding the pawl in released position while the shaft is rotating in the one direction, control means operated by the pawl, and means for operating said holding means in response to the operation of the control means by the pawl.

4. In combination with a shaft and power means for rotating the shaft in one direction, means for locking the shaft to prevent rotation thereof in the opposite direction, means operating in response to rotation of the shaft in the one direction for releasing the locking means, means for holding the locking means in released position while the shaft is rotating in the one direction, a control circuit including said holding means, a switch in said circuit operated by the locking means to energize the circuit upon release of the locking means and to operate the holding means.

5. In combination with a shaft and power means for rotating the shaft in one direction, means including a pawl for locking the shaft to prevent rotation thereof in the opposite direction, said shaft including means engaged by the pawl and operating in response to rotation of the shaft in the one direction to release the pawl from engagement therewith, means for holding the pawl in released position while the shaft is rotating in the one direction, a control circuit including said holding means, a switch in said circuit operated by the pawl to energize the circuit upon release of the pawl and to operate the holding means.

6. In combination with a shaft and power means for rotating the shaft in one direction, means including a pawl for locking the shaft to prevent rotation thereof in the opposite direction, said shaft including means engagedby the pawl and operating in response to rotation of the shaft in the one direction to release the pawl from engagement therewith, means for holding the pawl in released position while the shaft is rotating in the one direction including a solenoid having an armature linked to the pawl, a control circuit including said solenoid, a switch in said circuit operated by .the pawl upon release thereof to energize the solenoid for operating the armature to hold the pawl in released position.

7. In combination with a shaft and power means for rotating the shaft in one direction, a pawl for locking the shaft to prevent rotation thereof in the opposite direction, a ratchet wheel secured to the shaft and engaged by the pawl for locking the shaft, rotation of the ratchet wheel in the one direction releasing the pawl from engagement therewith, means for holding the pawl in re- 6 leased position while the shaft is rotating in the one (ii rection control means operated by the pawl, and means for operating said holding means in response to the operation of the control means by the pawl.

8. In combination with a shaft and power means for rotating the shaft in one direction, means including a pawl for locking the shaft to prevent rotation thereof in the opposite direction, a ratchet wheel secured to the shaft and engaged by the pawl for locking the shaft, rotation of the ratchet wheel in the one direction releasing the pawl from engagement therewith, means for holding the pawl in released position while the shaft is rotating in the one direction including a solenoid having an armature linked to the pawl, a control circuit including said solenoid, a switch in said circuit operated by the pawl upon release thereof to energize the solenoid for operating the armature to hold the pawl in released position.

9. In combination with a shaft and power means for rotating the shaft in one direction, means including a pawl for locking the shaft to prevent rotation thereof in the opposite direction, a ratchet wheel secured to the shaft and engaged by the pawl for locking the shaft, rotation of the ratchet wheel in the one direction releasing the pawl from engagement therewith, means for holding the pawl in released position while the shaft is rotating in the one direction, a control circuit including said holding means, a switch in said circuit operated by the pawl upon release thereof to energize the circuit and to operate the holding means.

10. In combination with a shaft and power means for rotating the shaft in a forward direction, means including a pawl for locking the shaft to prevent rotation thereof in a rearward direction, a ratchet wheel secured to the shaft and engaged by the pawl for locking the shaft, rotation of the ratchet wheel in a forward direction releasing the pawl from engagement therewith, means for holding the pawl in released position while the shaft is rotating including a solenoid having an armature linked to the pawl, a control circuit including said solenoid, a switch in said circuit operated by the pawl upon release thereof to energize the solenoid for operating the armature to to hold the pawl in released position.

11. In combination with a shaft and power means for rotating the shaft in a forward direction, means includmg a pawl for locking the shaft to prevent rotation thereof in a rearward direction, a ratchet wheel secured to the shaft and engaged by the pawl for locking the shaft, rotation of the ratchet wheel a forward direction releasing the pawl from engagement therewith, means for holding the pawl in released position while the shaft is rotating, a control circuit including said holding means, and a switch in said circuit operated by the pawl to energize the circuit upon release of the pawl and to operate the holding means.

12. In combination with a shaft and power means for rotating the shaft in a forward direction, a pawl for locking the shaft to prevent rotation thereof in a rearward direction, a ratchet wheel secured to the shaft and engaged by the pawl for locking the shaft, rotation of the ratchet wheel in a forward direction releasing the pawl from engagement therewith, means for holding the pawl m released position while the shaft is rotating control means operated by the pawl, and means for oper atmg said holding means in response to the operation of the control means by the pawl.

13. Imcombination with a shaft and power means for rotating the shaft in a forward direction, means including a pawl for locking the shaft to prevent rotation thereof in a rearward direction, said shaft including means engaged by the pawl and operating in response to forward rotation of the shaft to release the pawl from engagement therewith, means for holding the pawl in released position while the shaft is rotating, control means operated by the pawl, and means for operating said holding means in response to the operation of the control means by the pawl.

14. In combination with a shaft and power means for rotating the shaft in a forward direction, a circuit for energizing the power means, means for locking the shaft to prevent rotation thereof in a rearward direction, means operating in response to forward rotation of the shaft for releasing the locking means, means for holding the locking means in released position while the shaft is rotating, a control circuit connected to the first said circuit and including said holding means, and a switch in said control circuit operated by the locking means to energize the control circuit upon release of the locking means and to operate the holding means, said control circuit being inoperative when the power means is not energized.

15. In combination with a shaft and power means for rotating the shaft in a forward direction, a circuit for energizing the power means, means including a pawl for locking the shaft to prevent rotation thereof in a rearward direction, said shaft including means engaged by the pawl and operating in response to forward rotation of the shaft to release the pawl from engagement therewith, means for holding the pawl in released position while the shaft is rotating, a control circuit connected to the first said circuit and including said holding means, and a switch in said control circuit operated by the pawl to energize the control circuit upon release of the pawl and to operate the holding means, said control circuit being inoperative when the power means is not energized.

16. In combination with a shaft and power means for rotating the shaft in one direction, a circuit for energizing the power means, means for locking the shaft to prevent rotation thereof in the opposite direction, means operating in response to rotation of the shaft in the one direction for releasing the locking means, means for holding the locking means in released position while the shaft is rotating in the one direction, a control circuit connected to the first said circuit and including said holding means, and a switch in said control circuit operated by the locking means to energize the control circuit upon release of the locking means and to operate the holding means, said control circuit being inoperative when the power means is not energized.

17. In combination with a shaft and power means for rotating the shaft in one direction, means for locking the shaft to prevent rotation thereof in the opposite direction, means operating in response to rotation of the shaft in the one direction for releasing the locking means, means for holding the locking means in released position while the shaft is rotating in the one direction, a control circuit including said holding means, a switch in said circuit operated by the locking means to energize the circuit upon release of the locking means and to operate the holding means, and a speed responsive plugging switch in the control circuit operating under control of the shaft, said plugging switch de-energizing the control circuit when the shaft loses speed and stops rotating to render the holding means inoperative for holding the locking means in released position.

18. In combination with a shaft and power means for rotating the shaft in one direction, means including a pawl for locking the shaft to prevent rotation thereof in the opposite direction, said shaft including means engaged by the pawl and operating in response to rotation of the shaft in the one direction to release the pawl from engagement therewith, means for holding the pawl in released position while the shaft is rotating in the one direction, a control circuit including said holding means, a. switch in said circuit operated by the pawl to energize the circuit upon release of the pawl and to operate the holding means, and a speed responsive plugging switch in the control circuit operated by the shaft, said plugging switch de-energizing the control circuit when the shaft loses speed and stops rotating to render the holding means inoperative for holding the pawl in released position.

19. In combination with a shaft and power means for rotating the shaft in a forward direction, a circuit for energizing the power means, means for locking the shaft to prevent rotation thereof in a rearward direction, means operating in response to forward rotation of the shaft for releasing the locking means, means for holding the locking means in released position while the shaft is rotating, a control circuit connected to the first said circuit and including said holding means, a switch in said control circuit operated by the locking means to energize the control circuit upon release of the locking means and to operate the holding means, said control circuit being inoperative when the power means is not energized, and a speed responsive plugging switch in the control circuit operated by the shaft, said plugging switch de-energizing the control circuit when the shaft loses speed and stops rotating to render the holding means inoperative for bolding the locking means in released position.

20. In a'conveyor including a shaft supporting a belt, a motor connected to the shaft for rotating the shaft to drive the belt, a ratchet wheel secured to the shaft for rotation therewith, a pawl adapted to engage a tooth on the ratchet Wheel to prevent rotation of the shaft, said pawl being mounted on a pin for oscillation from a position spaced from the ratchet wheel to a position in engagement with a tooth on the ratchet wheel, a torsion spring on the pin and abutting the pawl for urging the pawl into engagement with a tooth on the ratchet wheel, a circuit for operating the motor and supplying power thereto, a control circuit connected to the first said circuit, said control circuit including a switch mechanically connected to the pawl for operation of the switch by the pawl, a solenoid connected to the switch and energized upon closing said switch, said solenoid including an armature linked to the pawl, said pawl being released from engagement with the ratchet tooth upon rotation of the ratchet wheel and closing the switch to energize the solenoid for operating the armature to hold the pawl in released position.

References Cited in the file of this patent UNITED STATES PATENTS