US1922635A - Hoisting machine - Google Patents

Description

Aug. 15, 1933. I R Q 5 1,922,635

HOIST-ING MACHINE Filed June 20, 1929 g/ as 35 L9 37 INVENTOR.

ATTORNEY Patented Aug. 15, 1933 i l 1 922 635 UNITED STATES PATENT OFFICE HOISTING MACHINE Robert 0. Post, Englewood, N. J., assignor to Post & McCord, a Corporation of New York Application June 20, 1929. Serial No. 372,290

11 Claims. (01. 18S82) My invention relates to improvements in hoist- Another object of my invention is to provide ing machines of the type in whichloads may a safety brake which is normally held in operbe raised and lowered by winding and unwindative position but is thrown out of engagement ing a cable on a hoisting drum. with the drum only when the service brake is in Usually such machines are operated by an controlling position.

electric motor or other prime mover which Another object is to provide a safety brake drives the drum in hoisting direction through of a type which when in operative position will the medium of a clutch. When lowering a load permit rotation of the drum in hoisting direction the clutch is thrown out and rotation of the but will permit rotation of the drum in reverse or drum is controlled by means of a service brake owering direction. acting thereon. Usually the service brake is Another object of the invention is to provide operated by a foot pedal under control of the a safety brake which is maintained in inoperoperator. The clutch is normally disconnected ative position by power means, so that in case and must be held manually in operating or enof failure of the power, the safety brake will gaging position, the purpose of this being to automatically be thrown into engagement to stop permit of more accurate control of the load. the drum a st eV 0 unwinding a- Thus the operator may let the clutch slip slightly tion. so as to ease up the load to a desired point. To Another object of the invention is to provide hold the load at any fixed point, the winding a safety brake of the character described above,

20 drum is usually provided with ratchet teeth Wi a auxi iary manual Control, whereby the adapted to be engaged by a pawl which can readbrake may be disconnected from power so that ily be thrown into engaging position by the it will. move automatically into operative en operator. To prevent the motor from running gagementwith the winding drum. in reverse direction an automatic brake is prot e Objects and advantages of y invention 25 vided on the rotor shaft which is effective only will appear in the following description of a against reverse rotation of the motor. Thus if Preferred embodiment and thereafter the 110V- for any reason power should fail while raising e ty' and Scope of the invention Will be pointed a load, the automatic brake will prevent the load out in the Claims. from falling so long as the operator holds the In the aeee p y w 30 clutch lever in engagement. This gives the oper- Figure 1 is a view inside elevation of a single ator time to throw the pawl into engagement with d u hoisting machine provided With y the ratchet. Furthermore, the operator could D OV d Sa y brake, Certain 1301110115 0f the stop the rotation of the drum by depressing the chine being removed to reveal features of the pedal and thus applying the service brake. invention;

35 However, the hoisting drum is normally free Fig. 2 is a'plan view of the hoisting machine,

and neither the motor brake nor the service and brake will come into play automatically to stop .Figs. 3 to 5 are detail views of parts of the the drum; for the motor brake although autosafety" brake mechanism, showing one of the matically stopping the motor will not stop the safety brake shoes in three different positions.

40 drum unless the clutch is held in engaging posi- As shown in the accompanying drawing, the, tion and the service brake is inactive unless the hoisting machine is provided with a base 10 on pedal is depressed. An operator might be sudwhich are mounted two brackets 11. Thesebrackdenly stricken, releasing the clutch lever and the ets provide bearings for the rotor shaft 12 of a pedal, and then there would be nothing to premotor 13. The shaft 12 is provided with a i 45 vent the load from falling. There is also a servo-brake consisting of abrake wheel 14 which possibility that an operator might become exis adapted to be engagedby brake shoes 15 and cited or confused, releasing the clutch and de- 16 supported on a yoke 1'7. The latter is mountlaying depression of the pedal until the load ed to oscillate on a stud supported in a bracket had gathered sufficient momentum to break the 18 secured to the base 10. The shoe 16 is di- 50 hoisting cable or wreck the machine. 7 rectly connected to one arm of the yoke, while 'It is an object of my invention to overcome the shoe 15 is connected to the other arm of such dangers by providing an automatic safety the yoke by means of a link 19.. When the brake which will automatically come. into play motorshaft turns in normal direction, as shown to prevent uncontrolled dropping or lowering of by the arrow in Fig. 1, the brake is ineffective 5 the load. and the shoe l5 merely trails along the brakewheel 14, because the point of attachment of the shoe 15 to the link 19 is above a line passing through the shaft 12 and the point of attachment of link 19 to the yoke. However, should the rotor be turned in the opposite direction, the shoe 15 would be dragged downward by the brake wheel 14, causing the yoke 17 to oscillate and force the opposite shoe 16 also into operative engagement with the brake wheel.

The brackets 11 also provide bearings for a shaft 20 on which is mounted a cable drum 21. The shaft 20 is driven by the motor 13 through a train of gears 22 so as to turn in the direction of the arrow in Fig. 1. The cable drum 21 is connected to the shaft through a friction clutch 23 and this clutch is operated by means of a lever 24. The construction of the friction clutch may be of standard type and is not shown in detail in the drawing. The clutch is normally spring-pressed in disengaged position but may be moved into andheld in engaging position by operating a clutch, lever 24.

The hoisting drum 21 is controlled by a service brake when lowering a load and to this endthe drum is formed at one end Witha brake surface 25 adapted to be engaged by a brake band 26. This band is anchored at one end to a bracket 2'7, while the free end of the band is secured to an arm 28 fixed upon a shaft 29.

- lever normally in the position indicated by broken lines at A in Fig. 1. The hoisting drum is also provided at one end with ratchet teeth 31 adapted to be engaged by a pawl 32; The pawl may be thrown by hand into or out of engagement with the ratchet teeth.

" The ratchet teeth are so formed as to prevent reverse rotation of the drum when engaged by the pawl, but will throw the pawl out of engagement when the drum is driven by the motor 1 to raise the load.

Secured to the drum near the forward side of the machine is a safety brake-wheel 33'. .This

is adapted to be engaged by a pair of brake shoes 34 and 35 carried by a yoke 36 pivotally mountedon the adjacent bracket 11. The brake shoe 34 is directly connected to one arm of the yoke 36 while the other brake shoe 35 is connected to the other arm of the yoke by means of an arm 37. This construction, it will be observed, is similar to that of the brake on the motor shaft with this difference, however, thatposition shown in Fig. 3. is formed with a rearward projection 35a which is urged by a spring 41 against a stop 37a formed on the arm 37. When the drum is driven in ii hoisting direction the parts will assume the po-' sition shown in Fig. 3 with the upper edge of the shoe 35 engaging and trailing on the brake wheel 33. When the direction of rotation of the drum is reversed the shoe 35 will be dragged flown to the position shown in Fig. 4, thereby rocking the yoke 36 on its pivot and forcing the The arrangement is such that.

However, when the solenoid is deenergized the arm will drop by gravity to the The brake shoe 35 shoe 34 also into engagement with the wheel 33. The latter is thus arrested. When the solenoid is energized the arm 37 is lifted, raising the shoe 35 clear of the wheel 33 and a compression spring 36a acting on one arm of the yoke 36 restores the latter to the position shown in .Fig. 1, with the other arm of the yoke bearing against a stop 362). In this position the shoe 34 is withdrawn from engagement with the wheel 33.

On one side of the bed of the machine, I have provided a control box 42 with a controller handle 43 by which current to the motor may be controlled. Current is fed into the control box through a pair of mains 44 and 44a, respectively.

, Tapped across these mains are a pair of leads 45 and 46, respectively, of which the lead 45 runs directly to one terminus of the solenoid, while the lead 46 runs to a contact brush 47 carried by the pedal 30. This'contact brush is adapted to engage a contact plate 48 which is connected by a line 49 to the other terminus of the solenoid 40. When the pedal is in its normal raised position A, the brush will be disconnected from the contact plate 48 and the solenoid will be deenergized and the safety brake will drop by gravity into a position to operate. When the pedal 30 is lowered to the operating position shown by full lines in Fig. 1, the circuit will be closed through the brush 4'? and plate 48 to the solenoid 40, and the brake shoe 35 will be raised out of operative engagement with the brake wheel 33, as in Fig. 5.

Thereafter further depression of the pedal 3Q down to the limit of its braking stroke (indicated by broken lines B, in Fig. 1) will maintain the electrical connection to the solenoid, so that the safety brake will continue to be held inoperative as long as the pedal is inoperative position. To permit throwing out the safety brake by hand, even should pedal 36 be depressed, a hand switch 50 is provided in the lead 46.

An electric lamp 551 is bridged across the mains 44, 44a, so that the operator will know at any time whether current is available to operate the motor or safety brake; for in case of any failure in current, due to theblowing of the fuse or for any other reason, the lamp 51 will be extinguished.

The operation of the machine is as follows: To raise a load, the operator throws in the clutch lever 24 and operates the controller handle 43 to energize the motor 13. This turns the drum in the direction of the arrow in Fig. 1 and although gravity is drawing the arm 37 downward there will be no braking action of the safety brake because of the direction in which the drum and brake wheel are rotating. When lowering a load, the operator, having'thrown the control handle 43 to cut off current from the motor, depresses the pedal 30 to apply the service brake. Then the pawl 32 is thrown out of engagement with ratchet wheel 31, the-clutch lever 24 is released and the load is lowered in the usual manner, under control of the service brake. The, instant the pedal is depressed to the position shown by full lines in Fig. 1 the brush 47 engages contact plate 48 energizing solenoid 40, which raises the arm 37 and holds the safety brake in inoperative position. If, for any reason, the operator should remove his foot from the pedal 30, re-

leasing the service brake, the pedal would spring,

up to the position A, under action of spring 300:. deenergizing the solenoid and permitting the brake shoe 35 to drop to operative engagement with the safety brake wheel 33. Thereupon the iii) safety brakewould act to arrest the hoisting drum and prevent the load fromdropping. The same thing would occur even if the operator were lowering the load under control of the service brake 26, should the current fail, because as soon as the solenoid is deenergized the safety brake will drop into operative position. The hand switch 50 could also be operated to deenergize the solenoid and throw in the safety brake. Thus, my invention provides against any emergency which might arise and renders the operation of the cable hoist safe at all times'and under all conditions.

I have shown my invention as applied to a single-drum hoisting machine, but it will be obvious that the same mechanism can be aplied to a multiple-drum hoisting machine; in other words, a safety brake would be used with each drum and would cooperate with the pedal of the normal service brake of said drum in the manner described above.

While I have shown a specific embodiment of my invention, I wish it to, he clearly understood that I do not limit myself to the particular type of brake or other mechanism illustrated, but reserve the right to make such changes in details of construction and in form and arrangement of parts as fall within the spirit and scope of the following claims.

I claim:

1. In a hoisting machine, the combination with a hoisting drum, of a service brake, means for operating the service brake to control and arrest rotation of the drum, a safety friction brake normally operating to arrest rotation of the drum, and means for rendering the safety brake inoperative when the service brake is operated.

2. In a hoisting machine, the combination with a hoisting drum, of a service bralre, means for operating the service brake to control and arrest rotation of the drum in one direction, a safety friction brake normally acting to arrest rotation of the drum in said direction, and means controlled by the first-named means for rendering the safety brake inoperative when the service brake is operated.

3. In a hoisting machine, the combination with a hoisting drum, of a service brake, a lever for operating the brake to control rotation of the drum, a safety friction brake normally in position to arrest rotation of the drum, and means controlled by said lever for withdrawing the safety brake from operative position while the service brake is in controlling position.

4. In a hoisting machine, the combination with a hoisting drum, of a service brake, a pedal for operating the brake to control rotation of the drum, a safety friction brake normally in position to'arrest rotation of the drum, and means controlled by said pedal for withdrawing the safety brake from operative position while the service brake is in controlling position.

5. In a hoisting machine, the combination with a hoisting drum, of a service brake, a pedal for operating the bralre to control rotation of the drum, a safety friction brake normally in operative position to arrest rotation of the drum, pow er energized means for holding the safety brake in inoperative position, and a control device actuated by said pedal for energizing said means to release the safety brake while the pedal is operated to control the service brake.

6. In a hoisting machine, the combination with a hoisting drum, of a service brake, a pedal for operating the brake to control rotation of the drum, a safety brake normally in operative position to arrest rotation of the drum, electrically energized means for holding the safety brake in inoperative position, a switch in the circuit of said means and controlled by said pedal for energizing said means while the pedal is in position to control the service brake.

7. In a hoisting machine, the combination with a hoisting drum, of a service brake, a pedal for operating the brake to control rotation of the drum, a safety brake normally in operative position to arrest rotation of the drum, electrically energized means for holding the safety brake in inoperative position, a switch in the circuit of said means and controlled by said pedal for energizing said means While the pedal is in position to control the service brake, and a hand switch also in said circuit.

8. In a hoisting machine, the combination with a hoisting drum, of a service brake, a pedal for operating the brake to control rotation of the drum, a safety brake normally in operative position to arrest rotation of the drum, electrically energized means for holding the safety brake in inoperative position, a switch in the circuit of said means and controlled by said pedal to close said circuit while the pedal is in position to control the service brake, a pair of power lines sup plying current to said circuit and a lamp bridged across said power lines.

9. I In a hoisting machine, the combination with a hoisting drum, driving means for rotating the drum in hoisting direction, and means for disconnecting the drum, of a service brake, means for operating the same to control rotation of the drum in reverse direction, means normally holding the safety brake in operative position, said safety brake when in operative position permitting rotation of the drum in hoisting direction and arresting rotation of the drum in reverse direction, and power actuated means for withdrawing the safety brake from said operative position while the service brake is in controlling position.

10. In a hoisting machine the combination with a hoisting drum and a motor for driving the drum and a source of power for energizing said motor, of a safety brake for controlling rotation of the hoisting drum, restraining means energized from said source of power for holding the safety brake inactive, a service brake movable into position to control rotation of the drum, and

means for disconnecting the restraining means from said power source when the service brake is in controlling position.

11. In a hoisting machine, the combination with a hoisting drum, of a service brake, means for operating the service brake to control and arrest rotation of the drum, a safety brake normally operating toarrest rotation of the drum,

means interconnecting the brakes whereby when the service brake is operated the safety brake will be inoperative, and manually controlled means for restoring the safety brake to operative condition while the service brake is in operation.

ROBERT C. POST.

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