US2245057A - Electric hoist - Google Patents

Description

June l0, 1941. Q H, SCHRAMM 2,245,057

ELECTRIC HOIST Filed Sept. 6, 1938 A 4 Shets-Sheet 1 June 10, 1941. C, H, SCHRAMM ELECTRIC HolsT 4 Sheets-Sheet 2 Filed Sept. 6. 1938 June 10, 1941. c. H. scHRAMM ELECTRIC HOIST Filed Sept. 6, 1958 4 Sheets-Sheet 3 June l0, 1941 c. H. scHRAMM ELECTRIC HOIST Filed Sept. 6, 1938 4 Sheets-Sheet' 4 NvsNw-opdk S ram/n CTTOQNEYS Puentes June io, 1941v y fittv'r'rcnlsr cammen. sans.. m. mem memesl lLIo'ore, Inc.,

Muskegon, ay eo Implicationy l'Septemlier 6, Serialv No. 228,512! onse-16s) The invention relates toelectricv hoists and has particular utilit asfapplied to holstsoi the port- One object of the present invention. is 'to pro- I vide an extremely compact electric hoist o! yminiweightand over-all dimensions. In particular this'obiect is accomplished by a novel armum v rangement or disposition ofthe parts of the hoist y, posed about a central vertical line of support in such manner as to require a minimum amount ci' cmmterweighting and to utilize to a maximum v The'gear case and motor arrangement described above is not inand of itself my'invention, but v, y is described and claimed in the copending appli-V,

and Ralph E. Smith,

cation of Preston Whitcomb l Serial No. 228,509 vfiled September 6, 1938, In accordance with one aspect of my inventibmthe over-ali dimensions and weight oi the hoist have means of which they are symmetrically disextent all available space within the housing of the hoist for the accommodation of such elements as the hoist brake and its associated Further objects and advantages of the invention will become apparent as the following delcriptionproceeds taken in connection with the accompanying drawingsin which:v f y Figure 1 is a general perspective view of an electric hoist embodying the'invention.

Pigs. 2 and 3 are respectively enlarged transverse and longitudinal vertical sectional views of the-hoist shown in Fig. l illustrating particu- Ialy the brake mechanism and associated parts with the remaining elements-of the `hoist indicated in dot dash lines.

Figs. 4 and 5 are respectively enlarged vertical transverse and longitudinal sectional views. similar to Figs. 2 and 3, of a hoist embodying a modiiled form of brake mechanism.

The invention has been shown herein (Fig. '1) for purposes oi' illustration and explanation of its various novel features, as embodied-'in a portablehoist which is adapted to be supported as a unitary structure from a single suitable supporting device such as a hook Il. A revoluble hoist member, such as a chain pinion Il (Fig. 3), is located directly below the hook I l so that the vertical i'orce applied tothe hoist by a load on the --hoisting member Il acts in a vertical line passing directly through the hook Il without any skewing or tilting of the hoist structure, A hoist line suchv as a-ro1ler I1 is pinion H. To identify the other generallements ofthe hoist in a few words, it includ reeved over the chain es a generf allyllat vertically disposed gear case Il, tothe` top or which che nook n 'is made :est and on' l the lower portion of which the pinion il is mounted, Also includedin the hoist is a horizontally' disposed electric driving motor Il boltedv to a complemental-cyllndrical extension I5 fashionccly on one side wall of the gear case, and'connected through a suitable speed reduction gearing within the gear case to theA chain pinion Il.

ying member 2| -positionoi the motor the shaft been markedly reducedv by utilizing the space between the end oi' the motor rotor and the g within the case Il to accommodate a brake v anism designated generally by the numeralvk Il. By so locating the brake mechanism substantially on the vertical center line of the hoist which passes through the hook Il and hoisting member I l, a symmetrical or balanced distribution of the oi'the center line location ci the brake mechanisin, it is unnecessary to provide any substantial t counterweighting on the gear case to counterbalance the brake mechanism as would be the case ii it were, for example, mounted on the outboard end oi' the motor shaft. Also, a standard motor shaft can be utilized as contrasted with a special shaft with an outboardextensionto receive the brake in the event that the the outer end of the'motor. Furthermore, the brake mechanism is housed by the extension :il on the gear case so that it is thoroughly pi-'otected. v

Turning now to a more detailed consideration oi'A the various partsA oi.' the hoist illustrated in Figs. 1,'2 and 3, it will bevseen that the driving motor I4 is'oi' generally conventional form (Fig. 2) and includes a stator ,I1 as well as a rotor Il carried by a horizontal shaft I9. The motor is l yhoused by a generally cylindrical frame or cas- Y provided with the usual end bell lint its outer end. The open' inner end of the mlotor casing 20 is'iltted on the cylindrical gear *case extension I5 and closed thereby. Through bolts 20* securethe motor in position. In this the gear case I3 and is Journaledin a sleeve bearing 22* fashioned in the gearcase itseli" ratherV than in the motor frame. The -outer end of the motor shaft is journaled in a bearing 23 carried bytheendbelti. f o

The gear case` I3 may be conveniently. rashicned as a casting and includes a cup-shaped part or shell 2l having a. vertically disposed generally fiat bottom wall or web `25 which formed brake-is mounted on' il extends within on the outer face of y the cylindrical extension il is integrally I (Fig. 3). A second integral extension 2l This controller y 43 depending from opposite sides of the pulley. With this arrangement the operator can shift the controller 29 to hoisting position by pulling on the cord end 42, and similarly to lowering posi- ,tion by pulling on the cord end 43. Throughout the oscillation of the controller rock shaft 3l, the depending ends of the control cord remain in substantially vertical position and tangential to the pulley 40. As a result, the length of the lever arm vbetween the line of action of the force Y applied to the depending cord end and the center embodies a rock shaft 3l oscillatable from a cen- A* trai neutral position, indicated bythe dot dash line marked N in Fig. 2, alternatively to either Y hoisting or lowering positions indicated respectively bythe dot dash lines marked H and L.

When the controller 29 is in its neutral position.

of the shaft 3| remains" substantially constant. Consequently, there is no appreciable variation in the torce required to shift the controller throughout its entire arc-of movement. This is to be contreated with the action in the event that a horithe driving matar is deenergized and while in the respective hoisting and lowering positions the motor is energized for corresponding directions of rotation. Preferably,fthe controller 29 and the ybrake mechanism Il are so interlocked that the brake will be released automatically whenever the controller is shifted to either hoisting or lowering position, but will be applied when the controller is injits neutral position, thereby preventing a gravital descent of any load on the hoist when the motor is stopped. K

'Iliebrake mechanism hss been shown as -being of the mechanical type and inthe particular form'illust'rated in Figs. 2 and 3 embodies -a brake drum 32 keyed to the projecting inner end portion'oi' the motor shaft I9. The brake (Fig. l) and then reeved over the pinion II with.

urged into frictional engagement with the brake.'

drum by a vhelical tension spring 35 anchored at its-ends to the opposed swingable ends otr the brake shoes.

Inl order to accomplish automatic actuation of th brake mechanism I6 in timed relation with the' movement of the motor reversing controller 33,'integral laterally extending arms 36 are fashionedio'nthepivoted brake shoes 33. These arms extend through suitable apertures 31 in the gear 'case lextension I3 and are provided with offset (see Fig. 3,) lower ends 33* embracing a cooperating lactuator cam 33 fast on. the controller rock shaft 3|. When the cam 38 is in its central or neutral position shown in Fig. 2, the brake shoes 33 are permitted yto engage the brake drum 32 underthebias of the spring 35. However, when the cam 33 is oscillated either clockwise or counterclockwisefto hoisting orlowering position. projections 3l* engage abutments 3.3. adiustably threaded in the odset lower-enden* of the brake shoe arms, and push the brake shoes apart out of engagement with the brake drum, thereby releasing the brake.

An actuator mechanism for the controller and brake cam 33 has been shown herein, which in the particular arrangement illustrated, embodies zontal cross ann is fixed to the controller rock shaft with control cords depending from its opposite ends and in which case tile force required to move the rock shaft increases with its displacement from its neutral position. This feature oi preventing an increase of force required for shifting the controller is particularly advantageous when the. controller is also used to actuate a mechanical brake mechanism such as that heretofore described. With such a brake mechanism, if the brake is released before the motor is energized by closure. of the controller contacts, the 1 load on the hoist will start to descend by gravity with consequent possible damage to the motor and its associated parts. Such undesirable operation is much more likely to take place in the event that a greater force is required by the operator to shift the controller into its i'lnal contact closing position. With` the pulley arrangement herein disclosed this possibility is largelyobviated.

If desired, an arrangement may be provided for automatically stopping the hoist at the upper and lower extremities of the movement of the hoist chain I2. In the construction illustrated, one end o! the chain I2 is secured to the isidev of the gear case I 3-by a yieldable tension spring 44 a suitable load supporting device such as a load hook 45 secured to the'free end of the chain."

In order to stop the hoist automatically at the end of its lowering movement, a ievei 4I is plv-.

, to its lowering position a lug 43 on the cam33 contacts the free end of the lever 46 and pushes it downward. "When the chain I2 reaches its exthe hoisting pinion I I being also pivoted on the gear case I3. This lever 4I isarranged to be contacted by an abutment 5I (Fig- 1) on the shank of lthe load hook A45 in the extreme hoist- 'ing position of the'chain. When the cam 33 is shifted to its hoisting position, a lug 52 (Fig. 2) thereon engages the free end of the stop lever 43 'and pushes it downwardly.- Then when the abutment 5I contacts the lever and returns it to its horizontal position, the cam and associated controller 29 are 'also returned to neutral position .to stopth'e driving motor I4.

The operrationjof the hoist will in general be i unders the foregoing description. As a brief rsume, iet it be assumed that the operator wishes to lift a load. In such case the load is attached to the hook 45 and the operator pulls down on the control cord 42, thereby tilting the controller rock shaft 3| until the longitudinal center line of the cam 38 occupies the position indicated by the dot dash line H in Fig. 2. In such position of the controller shaft and cam the driving motor Il is energized for hoisting and the brake 4I8 is released. To stop the hoisting operation, the operator simply releases the cord 42 so that a centering spring (not shown) in the controller 29, pulls the rock shaft 3l back to neutral position, thereby open-circuiting the driving motor. At the same time the cam 3B releases the brake arms IB so that the brake i6 is applied to hold the load suspended. Similarly to lower the load hook 45, the operator pulls down on the control cord Il thereby shifting the controller rock shaft to connect the motor `I4 for lowering and to' release .the brake Il simultaneously. Again the hoist is stopped at will by simply releasing the control cord so that the controller rock shaft may return to its neutral position.

Figs. 4 and 5 illustrate a modified form oi' electric hoist embodying the invention. The construction shown in these ngures is generally the same as that of Figs. 1 to 8, inclusive, except that a brake mechanism '53 of the electromagnetically actuated type is used rather than a mechanical brake such as the brake I8. The

same reference numerals have been ed in Figs. 4 and 5 to indicate identical parts and a repetition of the description of these parte is believed to be unnecessary'l As to the brake mechanism 53, which constitutes the changed element of the combination, it includes a rotatable element or brake drum Il keyed to the projecting inner end of the motor shaft il. This brake drum is lo cated within the cylindrical extension Il on the gear case just as in the case oi' the brake drum 32 of the brake mechanism II previously described. In the present instance, however, the cooperating non-rotatable brake element has been shown in the form of a flexible brake'band 5! anchcred at one end to the adjacent face of the gear case web 2l by a pin Il. The tree end of the brake band is secured to one end of a pin 51 carried by a link Il plvoted on the gear case extension Il by a pin Il. A helical compression spring l0 interposed between the forward end oi' the pin l1 and a fixed bracket Il serves to normally bias the pin l1 to a position in which the brake band l! frictionally engages the brake drum Il. `In order to release the brake the link 5l is pivoted in e counterclockwise direction (as viewed in Fig. 4) thereby compressing the spring 6U and moving the end of the brake band l5 away from the drum. In 'lder to adjust the tension on the brake band Il, the pin l1 is threaded in a suitably tapped 'hole Il* in the link 58 so that the pin l1 may be adjusted axially with respect to the link. A lock nut Il" holds the pin in its adjusted position.

An actuating solenoid, designated generally by the numeral O2, has been provided for moving the brake operating link il. This solenoid includes the usual stationary energizing windingy within a casing 63 and an axially movable plunger type armature 4. This plunger is connected with the outer end of the link 5l, which extends through a suitable aperture 58* in the side of the gear case extension II, by a pin and slot connection 65. When the solenoid is deenergized, the armature Il occupies the position shown in Fig. 2 in, which the brake is engaged due to the bias of the spring 60. Upon energize.- tion of the solenoid, however, the armature M is pulled downwardly, thereby oscillating the link 58 in a counterclockwise direction and releasing thebrake. The control circuit for the solenoid 62 is connected to the motor controller 28 so that the solenoid will be energized to release the brake 53 whenever the driving motor il is energized. The same synchronization of brake and motor operation is thus achieved electrically as was attained by the mechanical interconnection described above with respect to the holst shown in Figs. l to 3, inclusive.

Although certain particular embodiments ofh the invention have been shown and described in some detail for purposes of illustration, there is no intention to thereby limit the invention to such embodiments, but on the other hand the appended claims are intended to cover all modiiications and alternative constructions within the spirit and scope of the invention.

I claim as my invention:

l. An electric hoist comprising, in combination, an electric driving motor embodying a horizontally disposed generally cylindrical casing open at one end and closed at the other end and a rotorshaft projecting out through said one open end, a gear case having a generally vertical web therein with a complemental cylindrical extension thereon secured to the open end o! said motor casing to close the same, means in said gear case for journaling the projecting end portion ot said motor shaft, means including a hook fixed to the top oi' said gear case for suspending said gear case and motor as a unitary structure, a hoist member revolvably mounted on said gear case below said motor and substantially in vertical allnement with said hook, a speed reduction gearing'in said gear case drivingly connecting said motor and said hoisting member. and a brake for said motor including a rotatable brake drum fast on the portion of said motor shaft within said cylindrical extension on said gear case and a cooperating fixed brake element housed within said cylindrical extension. the weight oi said hoist being disposed symmetrically about a vertical line passing through said supporting means and said hoisting member.

2. An electric hoist comprising, in combination, an electric driving motor, embodying a horizontally disposed generally cylindrical casing open at one end and closed at the other and a rotor shaft projecting out through said one open end, a gear case having a generally vertical web therein with a complemental cylindrical extension thereon secured to the open end of said motor casing to close the same, means on said gear case for journaling the projecting end porf-` tion of said' motor shaft, means for suspending said motor and said gear case as a unitary structurel and attached to such unitary structure at a point adjacent the line of juncture between said motor casing and gear case, a hoist member revolvably mounted on said unitary structure below said motor and substantially in vertical alinement with said last named means, a speed reduction gearing in said gear case drivingly connecting said motor and hoist member, and a brake for said motor including a rotatable element fast on the projecting end portion of said motor shaft and a cooperating linedl element, the weight o! said hoist being disposed symmetrically about a vertical line passing through said supporting means and said hoisting member.

3. An electric hoist comprising. in comblnation. an electric driving motor embodying a horizontally disposed generally cylindrical casing open at one end and closed at the other andv a rotor shaft .projecting out through said one open end. a gear case having a generally vertical web therein with a complemental cylindrical extension thereon secured to the open end oi said motor casing to close the same, means on said gear'case for Journaling the projecting end portion of said motor shaft, means for suspending said motor and said gear case as a unitary structure and attached to such unitary structure at a point adjacent the line of juncture between said motor casing and gear case.v a hoist member revolvably mounted on said unitary structure below said motor and substantially in vertical alinernent with said last named means, a speed reduction gearing in said gear case drivingly connecting said'motor and hoist member, a brake ior said motor including a rotatable element fast on the projecting end portion of said motor shaft and a cooperating fixed element, a reversing controller for said motor disposed on the exterior ofI said unitary structure and including an oscillatable control shaft, said cylindrical extension on said gear case having an aperture therein, and means extending through said aperture for operatively connecting said brake and control shaft.

4. An electric hoist comprising, in combination, a revolvable hoisting member, a reversible electric motor connected in driving relation with said hoisting member, s reversing controller for said motor including a shaft oscillatable irom a central neutral position in opposite directions to respective hoisting and lowering positions,

'Y means including a brake for releasably holding Vsaid hoisting member against rotation, s. cam

on said controller shaft, means including a cam follower yieldingly urged into engagement with said cam for releasing said brake only when said shaft is shifted from neutral position into hoisting or lowering positions, manually loperable means for oscillating said shaft, s. hoist-line reeved over said hoisting member and disposed with one end secured to a member rigid with said motor and the other depending from said hoisting member and carrying an abutment, limit control means including two vertically shiitable members disposed on opposite' sides of said hoisting member, one of said vertically lsl'iiftable members projecting through the loop in the fixed end of the line to be raised by it at the extremity of lowering movement the other of said vertically movable members being disposed in the path of said abutment and above the same to b e raised by it at the extremity of hoisting movement, and

.of an electric motor and gear case disposed side by side in spaced relation with a horizontal, generally cylindrical, rigid extension on the gear case bridging the gap between them, said motor being generally axially alined with said extension and ilxed thereto, shaitlng extending from said motor through said extension into said casing, a brake mechanism housed within said extension and operatively connected to the portion of said shafting therein, supporting means iixed to the top oi said extension and a hoisting member rotatably mounted on the opposite or lower side of said extension in substantial vertical alinement with said supporting means, and a speed reduction gearing in said casing operatively connecting said shaiting and said hoisting member, the weight oi' the various elements being substantially symmetrically distributed about a vertical center line passing through said supporting means and hoisting member.

6. A portable electric holst having in combination, a rigid supporting structure comprising a central Vring member adapted to be sup- ,ported with its axis horizontally disposed and a gear casing rigid with one side of the ring mem- -ber and forming therewith-a unitary structure,

oi said ring member, said motor having-a rotor.

with a shaft projecting through said ring member into said gear casing, a bearing for said motor shaft carried by said unitary structure, a

hoisting member iournaled in the unitary structure at the lower side of said ring member on an axis disposed parallel with the motor shaft. reduction gearing in said casing operatively connecting said motor shaft and said hoisting member, .a brake drum fast on the motor shaft between said rotor and said bearing. a -pair of brake members disposed within-said ring member and pivotally mounted on said unitary structure for movement toward and from opposite sides of said brake drum, a reversing controller vfor said motor including a manually operable member, and means on said manually operable member operatively connected with said plvoted brake members to actuate the same,

CHRISTOPHER H. SCHRAMM.

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