US2211873A - Electric hoist - Google Patents

Description

P. WHITCOMB ELECTR Aug. 20, 1940.

IC HOIST Filed Oct. 6, 1937' 4 snags-sheet 1 Aug. 20, 1940. P. WHITCOMB 2,211,873

ELECTRIC HOIST Filed Oct. 6, 1937 4 Shuts-Sheet 2 I INVENTOR. 9

ATTORNEYJ P. WHITCOMB ELECTRIC HOIST Aug. 20, 1940.

Filed Oct. 6, 1937 4 Sheets-Sheet 3 INVENTOR. Fresh Whif'comb M ITORNEYS,

Aug. 20, 1940. P. WHlfCOMB 7 2,211,873

ELECTRIC HOIS'I Filed 001.. 6, 1937 4 Sheets-Sheet 4 INVENTOR. fiehm whifcomb RNEYS Patented Aug. 20, 1940 UNITED 'STATES PATENT OFFICE EIEOTRIO HOIST Application October 6, 1937, Serial No. 167,484

1 Claim.

This invention relates to improvements in small electric hoists.

An object of the invention is to provide a compact, simple and rugged hoist structure which 8 in proportion to the loads it is capable of lifting is remarkably light in weight and small in size.

A further object of the invention is to provide an electric motor hoist adapted for hook suspension, which is of such character as to provide 10, maximum strength and good balance about a central vertical axis with low cost and simplicity of construction.

Further and more specific objects of the invention as will appear below are successfully secured 15 thereby.

This invention resides substantially in the combination, construction, arrangement and relative location of parts, all as will be described in greater detail in the following specification.

20 In the accompanying drawings,

Figure 1 is a front elevational view of the structure of this invention;

Figure 2 is a side elevational view thereof withsome parts broken away;

25 Figure 3 is a top plan view thereof;

Figure 4 is an inside elevational view of the gear box and parts associated therewith showing the frame adjacent the chain pinion in crosssection;

30 Figure 5 is an elevational view looking into the gear box with its cover removed, with some parts broken away;

Figure 6 is a cross-sectional view taken on the line 6-45 of Figure 2; and

35 Figure 7 is a view looking into the brake hous- *-ing on the plane 'l'| of Figure 1.

The full nature of the novelty and scope thereof as incorporated in this invention will be more quickly understood by first describing the struc-- 40 tural details thereof. The main frame of the de-. vice consists of a ring-like casting I within which a standard fractional horsepower electric motor 2 is secured in the manner clearly illustrated. The housing casting l is provided with an inte- 45 gral journal member 4 at the bottom thereof provided with an integral bracket member 5 to which The gear housing is provided with aion 8 which meshes with the driven gear '9, the projecting inner end of the motor shaft being journaled in a bearing I keyed in the gear housshaft I3. Shaft l3 extends through the back of the gear housing and into the journal housing 4.

As is clear from Figures 1 and 4, the journal 10 housing is divided longitudinally into two parts to provide an opening into which the chain pinion fits. The pinion is mounted on a short shaft I 3a. The pinion '5 lies in a bearing block I4 which is U-shaped in form so that the pinion l5 lies between the legs thereof, as is clear from Figure 4. The block l4 closes the lower half of, the space in the bearing member 4 and is secured to and held in place by means of a bar I5 which is attached to the casting, as is clear from Fig- 2 ures 1 and 4, by screws or bolts. By this arrangement the chain is guided in its movement over the pinion l5.

The hoist chain is shown at It, the'upper free end of which is attached to the casting l by means of a hook I! mounted on the casting. As is clear from Figure 4, the chain hangsin a loop between the pinion 15 and the hook ll. The other end of the chain is provided with the loading hook l8 which is attached thereto by means of a U-shaped yoke l9 and rivets, as is clear from Figure 4. Secured by these same rivets is an L-shaped bracket 20 which performs a function which will be described later. The suspension book, by means of which the device is supported .from overhead, is shown at 2| secured in any suitable manner to the casting I. It is noted that the hook 2| is mounted directly over the pinion l5 and the weight of the various parts on either side of the axis which includes them is so distributed that the device is nicely balanced. This is of practical advantage since the loads on the chain are directly transmitted through the casting I to the overhead support without danger of I causing the device to tip or swing.

As shown in Figures 6 and 7 the shaft l0 extends into the brake housing 22 and has secured on the end of it a disc-like member 24 which in turn loosely supports the inner brake disc 25.

The disc 25 is held properly positioned and is 30, positioned to engage the ring 24. When the' member 3| is revolved in either direction the disc 30 is caused to have an axial movement either towards or away from the friction ring 25. Secured to the outer face of the member 35 by means of a screw 33 is the lever 32. At one end of the lever 311s a handle 34 secured thereto by a suspending cord while there is mounted on the other end of the lever a weight 35. The threads of the member 3| are pitchedin such a direction that when lever 32 is free the weight 35 tends to move the member 3| and the disc 30 inwardly to cause the disc 30 to engage the ring 25.

As will be apparent by tracing the motions through, a weight suspended on the hook i6 will tend to rotate the disc in a direction so as to tend to cause the member 3| to move inwardly. Thus all of the forces involved. including the weight 35, are in a direction to tend to cause the brake to grip and hold the chain against movement. The various lever arms involved are so proportioned in relation to the strength of the springs 29, of which there are several distributed circumferentially around the disc 24,

' that all loads on the hook I8 up to the capacity,

of the device are insufiicient to cause any movement of the mechanism unaided by the motor. However, when the motor is energized to move the hook l8 downwardly the resistance of the 40 brake mechanism is overcome so that the hook I desired to lower the hook bearing a load without the ring 26 to release the brake.

employing the motor this is done by releasing the brake, which is accomplished by pulling down on the handle 34. This rotates the member 3| in a direction so that the disc 30 moves away from By making the arm 32 of the proper length this control may be very sensitive and the loaded hook may be caused to descend very slowly or in small increments so as to be always under control. As soon as the handle 3| is released the .weight 35 plus the tendency of the rotation of the disc 24 under the load of the hook are such as to cause the brake to firmly grip and stop all movement.

Mounted on top of the gear casing 3 is a switch 35, the details of construction of which are unnecessary to a full understanding of the invention except to note generally that when the switch is turned from its neutral position in one direction the motor, which is reversible, is energized for rotation in one direction, and when the switch is moved from neutral to its other position the motor is energized in the reverse direction. In this connection, depending upon the nature and field of use of the device, the switch may be of a type which requires continuous conscious effort to maintain it in either actuated position or may be of a type which remains in actuated position until returned to neutral position. The actuating shaft for the switch is shown at 38 and has secured thereto a This ring is attached by rivets. as is.

pulley 35 and a pinion 4|. Mounted on the pulley and preferably attached thereto are a pair of depending cords 4| which pass through guide eyelets 42 mounted on the gear housing and terminate in handle grips 41 and 44. At 45 and 45, respectively, are indicators which indicate, for example in the case of indicator 45, that when handle 43 is pulled downwardly the hook will move down and when handle 44 is pulled downwardly the indicator 45 indicates that the hook will move up.

At 41 is a rack member meshing with the pinion and secured to a vertical slidable bar mounted in a suitable guide member 45 on the rear face of the gear housing 3. The lower end of the bar 48 isprovided with a pin 5|! which extends through the slot in the end of a lever 5| pivotally mounted intermediate its ends on the rear face of the gear housing, as is clear from Figure 4. The other end of the lever 5| is provided with a pin 52 which is positioned to be in the path of travel of the arm 20 on the hook yoke. Pin 50 is positioned so as to be over the loop in the chain I5 between the chain pinion l5 and the hook I1.

To operate the device, handle 43 is pulled downwardly which rotates the pulley 39 and closes the switch to set up connections-so that the motor 2 will rotate pinion 15 through the gear train in a direction to move the chain downwardly. At the same time pinion 40 moves the rack 41, bar 48, and right hand end of lever 5|, Figure 4, downwardly so that the lever is in the dotted position shown. Thus the hook is lowered whether loaded or not, and if by oversight switch 35 is not shut off in time the shortening loop in the chain I6 will ultimately engage the pin 50 to move bar 48 and rack 47 upwardly, which will move the switch back to normal position and deenergize the motor- Thus the mechanism is stopped before the chain is drawn tight, eliminating'any tendency to break the chain or the hook ll. Lever 5| is at the same time moved to neutral or full line position. The nature of this automatic stopping mechanism is such that even if the operator should hold on to the handle 43, which he would do particularly in the case of a switch that had to be held in operated position, the switch will be returned to neutral position. To raise the hook, handle 44 is pulled downwardly which rotates the switch in the reverse direction and moves lever 5| to the other dotted position (Figure 4) through the rack 41 and the bar 48. In this case the pin 52 is downward and in the event that the operator overlooks shutting off the device in time the arm 20 will engage the pin 52 moving lever 5| back to full line position and at the same time returning the switch 'to neutral position to deenergize the motor.

The device of this invention is amazingly small, compact and rugged. The device, as illustrated, has an over-all width of not much more than a foot and weighs in its present form but fifty pounds. Nevertheless, the device is capable. of lifting a load of five hundred pounds or in the ratio of ten to one with respect to its weight. It is anticipated that upon further design the weight may be reduced to about thirtypounds which will render the device easily portable and of great utility. Because of the simplicity of the structure involved the cost of manufacture is relatively low and the device is already demonstrating commercially these remarkable characteristics.

It will be apparent to those skilled in the art as that the details of construction employed for illustrating the principles of the invention may be varied Without departure from the true nature and scope of the invention. It is desired, therefore, not to be limited to the disclosure but rather to the appended claim.

What I seek to secure by Letters Patent is:

A portable electric hoist having, in combination, a supporting structure comprising a. ring adapted to be supported with its axis horizontally disposed, an electric motor having a drive shaft, a. cylindrical motor casing carried by and projecting from one end of said ring, and an end shield on said casing providing a bearing for said shaft and closing the projecting end of the casing, the other end of said motor shaft projecting from said ring, said supportingstructure further com-prising a journal member formed integrally with said ring and positioned at the bottom of said ring, a gear case rigid with said journal member at the end opposite said motor and providing a bearing for said projecting end of the motor shaft, and a hoisting mechanism comprising a driven shaft journaled in said journal member in spaced parallel relation to and below the motor shaft, and speed reduction gearing mounted in said casing and connecting said shafts.

PRESTON WHITCOMB.

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