US2321525A - Electric hoist - Google Patents

Description

June 8, 1943. c. s. scHRor-:DER

ELECTRIC HOIST Fiied Nov. 1e, 1940 INVENTOR QN N u w @nw @n wn.

ATToRNEY Patented June 8, 1943 ELECTRIC HOIST Charles S. Schroeder, Philadelphia, Pa., assignor to The Yale & Towne Manufacturing Company, Stamford, Conn., a corporation of Connecticut Application November 16, 1940, Serial No. 36.5,934

(Ci. 25d-168) 4 Claims.

Lspeeds which are generally approved for industrial use. Many times it becomes necessary to elevate such a case, it is readily appreciated that with hoists having a rather fast lifting speed, it becomes almost impossible to determine when to shut off the power to the motor so that the load will be moved to the particular level desired. Thus, it will be appreciated by those skilled in the art that when the power to the lifting motor is shut on, a certain time interval must elapse before the motor stops and the brake is applied. During this time interval, the Aload may move several inches. Therefore, it is very dimcult for an operator to control the hoist motor for positioning the load as may be required, even when he resorts to inching, a term which will be understood by those skilled in this art.

I have conceived and developed an improvement on a standard type of electric hoist, such as is disclosed in my patent application Serial No. 236,037, filed October 20, 1938, whereby I can readily combine with the structure of a standard hoist, means for operating the hoist at a speed which will facilitate the controlling of the load movement. It is a feature of my invention that I utilize a second and smaller motor which is adapted to drive the usual main motor of the hoist, and through that main motor, to drive the hoist gearing and the drum connected to that gearing. As a further feature of my invention, the second motor is adapted to drive the first motor through a second set of gearing whereby to reduce considerably the ultimate speed of movement of the hoist drum. As a matter of fact, in the preferred form which my invention takes, the small second motor drives the large motor at onetwenty-fourth its own speed. As a further feature of my invention, the main hoist motor is s arranged that it is not itself power actuated in ,Y any Way when the second lor smaller motor is driving the hoist, the first motor then functioning merely as a connecting unit between the second v or lower the load to a predetermined level. In

motor and its gearing, and the gearing driven by the said first motor.

It is a further feature of my invention that I connect the second motor and its gearing to the first motor through an. electromagnetically controlled clutch, the mechanism being so arranged that the clutch is energized at thesame time that the second motor is energized, whereby to connect to the first motor, the second motor and its gearing. When the first motor, or the main motor of the hoist is energized, it is a preferred feature of my invention that the second motor and the electromagnetic clutch be deenergized so that the firstv motor will operate freely of the second motor, its gearing, and the magnetic clutch, and to actuate the hoistingdrum through the first set of gearing only, as though there were not present, a second motor.

I have thus described generally the operation of my invention in order that my detailed description of a particular form thereof may be better understood. Naturally, those skilled in the art will readily perceive the advantages of my contribution to the art, and will appreciate that the said contribution may be embodied in many forms other than that particular form shown in the drawing and described hereinafter.

Referring now to the drawing, Fig. 1 is a partial vertical section of my hoist showing the parts thereof. Fig. 2 is an enlarged section through the magnetically operated clutch. Fig'. 3 is a schematic view of the electric wiring for controlling the operation of the several parts of my hoist.

Referring now more particularly to the drawing, the main portion of my hoist is constructed exactly as is set forth in my application supra, and for that reason I shall not describe this portion of my invention in detail. Suffice it to say that this main portion includes a motor M-I of the type in which the eld may be connected in series or parallel, the shaft II of the motor being adapted to drive through a splinedcoupling I2, a further shaft I0, which in turn drives a suitable set of gearing G-I, which in turn is in driving relation to a hoist drum I3. `Rotation of the hoist drum I3 winds and unwinds the cable Il for lifting a load supported by the said cable through the intermediary of the block I5 .and its hook I6. As is set forth in my application referred to above, rotation of the motor M-I in one direction or the other effects the rotation of the hoist drum in one direction or the other, to elevate or lower the load on the hook I6, the shutting off of the power to the motor M--I effecting simultaneously the application of a suitable brake mechanism for stopping the rotation of the hoist drum I3.

For carrying out the purposes of my invention that I have already described' generally, I extend the left hand end II of the shaft of motor M- I, as designated by the reference numeral II,.so that there may be keyed to this shaft extension, as at I8, the driven portion I3 of anelectromagnetically operated clutch C. In itself, this clutch is of a type well known in the art, and per se does not form a part of my invention. Any type of electrically controlled clutch might conceivably function just as well as 'does the particular form of clutch shown in detail in Fig. 2.

For housing and supporting the end I'I of the shaft II, I utilize a casing portion 20 formed as .an adaptor of the main casing of the motor M-I and suitably bolted thereto by means which are not illustrated here. Secured as by a series of bolts 2I to the casing portion 20, is a casing 22 in which the clutch C is house'd, as is best seen in Fig. 1. The driving portion of this clutch is designated by reference numeral 23, and is keyed at 24 to a shaft 25. Rotatable with the'driving portion 23 are collector rings 26 suitably insulated as at 21 for receiving current from a pair of brushes 28a mounted on the casing 22, it being understood that this current will be supplied to the coil 28 of the eleotromagnetically operated clutch for suitably coupling the driving portion 23 to the driven portion I9 in a manner which is well understood by those skilled in the art. It may be well to note that when the clutch C is deenergized, the ball 29 carriedon the driving portion 23, is spring pressedthrough the spring 30 against a plate 3I of the driven portion 'I9 for maintaining the portions I9 and 23 separated,

and with a minimum of -friction therebetween.

A second set of gearings G-2 is housed within a casing 33 bolted to the casing 22, and to which in turn is bolted the casing 34 of a second motor M-2. The shaft 25, to which is keyed the driving portion 23 of the magnetic clutch, is driven through the intermediary of the gearing G-2, by the shaft 36 ofthe motor M-2.

From the description which has been given, it will be readily appreciated that when the magnetic clutch C is energized, the driving portion 23 thereof is secured to the driven portion I9,

and if the motor M--2 is at the same time ener- F rotation will be at a speed which will be determined by the speed of the motor M--2 and the gearing G-2. Naturally, it is arranged that the motor M--2 will be yenergized at the same time that the magnetic clutch C is energized, and that while the lmotor M-Z and the clutch are so energized, the motor M-I will be deenergized. Reversely, when the motor M-I is energized, the magnetic clutch and the secondary motor are deenergized, al1 as will be appreciated.

In order that the electric control of the motors M-I and M-2 and the magnetic clutch may be betterA understood, I shall refer now to Fig. 3 in which I show schematically the electric circuits in which the motors M-I and M2 and the various other parts are located. The source of current, designated by plus and minus signs, is connected through the reversing switch 31 to the switch 38. The reversing switch I'I'I is operated in a manner well known in the art by buttons 39 and 39a, best shown in Fig. 1, on a conf the hoist may be operated by the second motor M-2 at a very slowV speed, and for the purpose indicated. On the other hand, when the switch 38 is thrown into engagement with the binding posts 42, 43, the large motor M-I will be enerlgized for operating the hoist drum at the usual commercially required speeds.

I now claim:

1. In a hoist of the'class described, a hoisting member, a motor for driving said hoisting member, a set of gears intermediate said motor and hoisting member and through which said motor drives said hoisting member, a second motor in axial alignment with said iirst motor, a second set of gears driven by said second motor, a clutch positioned between said second set of gears and said first motor, the driven portion of said clutch being formed, in eiect, as an extension of the shaft of said rst motor, while the driving portion of said clutch is, in effect, an extension of the final gear of said second set of gears, means for actuating said clutch. electric circuits for said motors, and control means for eifecting the actuation of said clutch by said means and the simultaneous energizing of the circuit of said second motor whereby said second motor is energized to drive said second set, of gears as said clutch connects said first motor to said second set` of gears, whereupon said second motor rotates the hoist ing member through the intermediary of said first motor and said first set of gears and while said first motor remains de-energized.

2. In a hoist of the class described, a hoisting member, a motor for driving said hoisting member, a Yset of gears intermediate said motor and hoisting member and through which said motor drives said hoisting member, a ysecond motor in axial alignment with said first motor, a second set of gears driven by said second motor, a casing secured between said motors in which said gears are mounted, a clutch positioned between said second set of gears and said first motor, the driven portion of said clutch being formed, in effect, as an extension of the shaft of said first motor, while the driving portion of said clutch is, in efl'ect,` an extension of the final gear of said second set of gears, means for actuating said clutch, electric circuits for said motors, and control means for effecting the actuation of said clutch by said means and the simultaneous energizing of the circuit of said second motor whereby said secondmotor is energized to drive said second set of gears as said clutch connects said first motor to said second set of gears, whereupon said second motor rotates the hoisting member through the intermediary of said iirst motor and said first set of gears and while said nrst motor remains de-energized.

3. In a hoist of the class described, ahoisting member, a motor for driving said hoisting member, a set of gears intermediate said motor and hoisting member and through which said motor drives said hoisting member, a second motor'in axial alignment with said first motor, a second set of gears driven by said second motor, a casing secured between said motors in which said gears are mounted, an electromagnetic clutch positioncd between said second set of gears and said first motor, the driven portion of said clutch being formed, in effect, as an extension of the shaft of said rst motor while the driving portion of said clutch is, in eiect, an extension of the nai gear of said second set of gears, electric circuits for said motors and clutch, means for closing simultaneously the electric circuits through said second motor and said clutch while opening the circuit through said rst motor whereby said second motor drives said hoisting member through the intermediary of said second set of gears, said clutch, said irst motor and said rst set o! gears.

4. In a hoist of the class described, a hoisting member, a motor for driving said hoisting member, a set oi gears intermediate said motor and i hoisting member and through which said moto:

drives said hoisting member, a second motor in axial alignment with said rst motor, a second set of gears driven by said second motor, a casing secured between said motors in which said gears are mounted, an electro-magnetic clutch positi'oned between said second set of gears and said rst motor, the driven portion of said clutch being formed, in effect, as an extension of the shaft of said first motor while the driving portion of said clutch is, in effect, an extension of the nal gear of said second set of gears, electric circuits for said motor and clutch, means for closing simuitaneously the electric circuits through said second motor and said clutch while opening the circuit through said rst motor whereby said second motor drives said hoisting member through the intermediary of said second set of gears, said clutch, said rst motor and said first of gears, said means being adapted also for opening the circuit through said clutch and second motor while closing the circuit through said rst motor, whereby said rst motor will drive said hoisting member free of said second motor and said second set of gears.

CHARLES S. SCHROEDER.

Images