US2991976A - Power-driven hoist - Google Patents

Description

July 11, 1961 c. CARROLL POWER-DRIVEN HOIST Filed Jan. 15, 1958 4 Sheets-Sheet 1 na 16 Ira/@715 July 11, 1961 CARROLL 2,991,976

POWER-DRIVEN HOIST Filed. Jan. 15, 1958 4 Sheets-Sheet 2 July 11, 1961 c. CARROLL 2,991,976

POWER-DRIVEN HOIST Filed Jan. 15, 1958 4 Sheets-Sheet 3 July 1961 c. CARROLL 2,991,976

POWERDRIVEN HOIST lfilc/erzl'br 7X 75 Char es Cbrre @Zibrrzeg Y nite ttQS 2,991,976 POWER-DRIVEN HOIST Charles Carroll, Danville, Ill., assignor to Duff-Norton Company, Pittsburgh, Pa. Fiied Jan. 15, 1958, Ser. No. 709,154 7 Claims. (Cl. 254-168) The present invention relates to a power driven hoist. More particularly, the invention resides in the compartmentalization, orientation of the power train, and location of the auxiliary elements of the hoist.

With increasing emphasis by industry on extensive mechanical handling of materials in shops and warehouses, it becomes desirable to employ power-driven hoists wherever possible. In addition to the lifting and loading functions of hoists, they should be light in weight to permit their rapid movement throughout the installation on overhead monorail systems. This reduction in weight also produces the advantage of facilitating the removal of the hoist to different working stations. With the reduction of weight, however, strength, safety, and dependability must not be sacrificed. In addition, reducing the weight of a hoist must not increase its maintenance costs. Indeed, the emphasis is continually placed upon low maintenance products, and ready accessibility for adjusting and cleaning.

In view of the foregoing, it is the general object of the invention to provide a power driven hoist which is light-weight, efficient, and safe.

A more specific object is to furnish a power-driven hoist with a power drive which reduces the enclosure size by reducing the speed reducer gear train size. A related object is achieved by eliminating a hollow sprocket and by-passing the sprocket with the motor drive so that the limit switch couples directly to the sprocket drive without excess gearing. Also, by eliminating the hollow sprocket, the further objective of permitting five and even three-pocket sprockets may be achieved.

Another objective of the invention is to compartmentalize the various elements of the hoist to isolate the lubricated elements and dry running elements into separate areas.

A further objective is achieved by by-passing the sprocket with the motor drive thereby permitting a high, dry, and safe location of the safety brake.

Still another object of the invention is to utilize smaller shafting in the power train thereby reducing bearing sizes and, naturally, bearing costs.

Further objects and advantages of the present invention will become apparent as the following description of an illustrative embodiment proceeds, taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a partially broken perspective view of a power-driven hoist illustrative of the present invention.

FIG. 2 is an enlarged transverse section of the powerdriven hoist taken along section 2-2 of FIG. 3.

FIG. 3 is an enlarged partially broken, longitudinal section, illustrating the internal portions of the powerdriven hoist.

FIG. 4 is a transverse section showing the speed reducer gear train of the power hoist, taken along section line 44 of FIG. 3.

FIG. 5 is a perspective, exploded, partially diagrammatic View of the power train and some auxiliary features of the subject hoist.

FIG. 6 is a transverse section through the auxiliary system housing, showing the safety brake and limit switch as taken through section 6.6 of FIG. 3.

FIG. 7 is a partially diagrammatic view, illustrating the operation of the safety brake.

FIG. 8 is a top view of the chain stripper and lead-in element.

In its broadest sense, the invention contemplates a power hoist, conventionally driven by an electric motor and normally coupled to an overhead monorail trolley. In the illustrative embodiment, it will be seen that the motor and housing is offset upwardly from the remainder of the housing since the motor drive shaft bypasses the chain sprocket and runs into the gear box at a level above the other mechanism. The far end of the motor drive shaft penetrates the auxiliary housing and is keyed to the safety brake drum at its end. The chain sprocket drive shaft extends into the auxiliary housing and serves as the direct drive shaft for the limit switch. All of the walls in the compartments serve to support the ball bearing journals for the various drive shafts. The speedreducing gears are all oriented in one compartment and are located low in the compartment for better lubrication and to lower the center of gravity of the hoist. The detailed advantages flowing from the foregoing general orientation will be more fully appreciated in the course of the fol-lowing detailed description.

Referring now to FIGURE 1, it will be seen that the subject power-driven hoist 10 is suspended from a monorail trolley 11, which rolls on the monorail beam 12. The hoist is controlled by a position button pistol grip switch 14 connected to the hoist by means of power control cable 15. The subject hoist powers a chain 16 at one end of which is secured a hoisting hook 18. It will be appreciated that although a chain is employed as the flexible tension member, in the following description and in the drawings, the invention is similarly applicable to the use of a cable, or other known flexible tension means. Before turning to the intimate details of construction, it will prove helpful to review the power train orientation illustrated diagrammatically in FIG. 5. There it will be seen that the motor 20, normally an electric motor of varying voltage and phase designation, has a motor drive shaft 21 extending from one end. The far end 22 of the motor drive shaft 21 is externally splined so that the motor can be readily removed from the hoist for servicing. An internally splined coupling 24 couples the motor drive shaft 21 to the motor drive shaft ex'- tension or pinion shaft 25, at its splined end 26. The far end 23 of the pinion shaft 25 is also splined for attaching to the drum 29 of the safety brake assembly 30. Since the motor drive shaft 21 and its extension, the pinion shaft 25, are driven at motor speed within the power train, the orientation of the safety brake at the shaft end 28 gives the brake the maximum effective mechanical advantage.

The reducing gear assembly is unique in that by one simple gear change the chain speed can be altered from 16 feet per minute to 32 feet per minute, without modifying the hoist construction. In addition, the speed-reducing gears also serve to transmit the power from the motor drive shaft 21 to the sprocket 31, which is at a lower leveland not coaxial with the motor drive shaft 21, as in conventional hoists. The advantages flowing from this orientation are numerous. The sprocket bearings can be substantially smaller and, therefore, less expensive. Because of the lack of internal shafting, a sprocket shaft extension 32 can serve to activate the limit switch assembly 35. In addition, because the sprocket drive shaft 64 may be made without a center bore, the sprocket 31 can be designed small enough to function as a threepocket or five-pocket sprocket.

The pinion shaft pinion 36 is coaxial with the motor drive shaft 21, and sufficiently wide to accommodate a1- ternate gear arrangements. The pinion shaft pinion 36 is coupled to the 2:1 intermediate interchange gear 38 and its associated pinion 39. The sprocket pinion drive gear 40 is driven by the interchange pinion 39 and is coupled to the sprocket gear pinion 41, which in turn drives the sprocket gear 42. As will become readily apparent from an inspection of FIG. 4, the interchange gear 38 and its associated pinion 39, may be removed, and a larger sprocket pinion drive gear 40 inserted which couples directly to the drive shaft pinion 36, operating through a locus in dicated by the phantom lines 44. Thus, it will be seen that the unique power train is sufficiently flexible to permit a 2:1 gear change in the field, sufllciently compact (see FIG. 3) to hold the speed reducer assembly proportions to a minimum, and provides two spaced drive shafts for the safety brake assembly 30 and limit switch assembly 35, which can be located in an auxiliary housing for Shielding from dirt and ready accessibility for servicing.

Not only is the gear train assembly unique, but it cooperates by a unique housing arrangement which reduces the cost of assembling the hoist, retains a light-weight construction, and serves to isolate the dirt and grease associated with hoist operation, into those areas best equipped to accommodate the dirt and grease. By referring to FIG. 3 it will be seen that the motor carries its own motor housing 45, which is secured by means of through bolts 46 to the sprocket housing motor side half 48. The speed reducer side 49 of the sprocket housing extends to the auxiliary system housing 50. The auxiliary system housing 50 is secured to the speed reducer housing 49 by means of through bolts 51 oriented at the stations indicated in FIG. 2. For ease in disassembly, it will be seen that the motor and its housing can be removed by removing the motor mounting bolts 46, and the auxiliary system housing 50 can be removed by the release of the cap screws 52, and thereafter the locking bolts 51. A lock ring 54 secures the safety brake drum 29 on its spline 2.8, but when removed permits the pinion drive shaft to slide through its associated hearing. The limit switch drive shaft 32 is threaded at one end 33 for a threaded attachment to the sprocket drive gear 42, and held in place by the lock nut 37. Upon release of the lock nut 37 and the unscrewing of threads 33, the limit switch drive shaft 32 is free to release with the auxiliary housing 50. The two halves of the sprocket housing are held in place by means of a plurality of bolts. The sprocket housing, in turn, serves to position and secure the chain guide assembly. As the description of the housing becomes more detailed, the advantages flowing from its orientation and relationship with the power drive become apparent. For example, in viewing FIG. 3, it is apparent that the motor, designed to run dry and clean, can be offset above the sprocket area. The sprocket, on the other hand, is constantly being jammed by dirt, grime, and other foreign material; but because of the unique orientation of the sprocket beneath the motor drive shaft, the dirt and grime, are naturally isolated from the motor drive shaft. Similarly, the gear train is separated from the sprocket in a separate chamber where it can be grease lubricated. Each of the gears can be splash lubricated, or grease lubricated, without requiring the grease packing, or lubricant level, to rise above that of the motor drive shaft. This orientation serves to keep the motor and sprocket housing clear of the speed reducer lubricant, and also serves to shield the safety brake assembly from contamination, which would reduce its effectiveness as well.

Because the sprocket drive gear 42 is cantilever mounted by the sprocket bearings 55, 56 (not shown in detail), a simple oil seal 58 (see FIG. 3) seals the limit switch drive shaft 32 so that the limit switch assembly 30 is dry in operation.

A unique chain guide assembly 60, comprising a pair of crescent-shaped parallel retaining plates 61 (see FIGS. 2 and 3) is employed around the upper half of the sprocket 31. As will be noted in FIG. 3, the parallel plates 61 flank the chain link groove 59 and serve the function of retainers while the chain passes over the upper half of the sprocket 31. As the chain leads into and comes off of the lower portion of the sprocket 31, it must be both led into and stripped from the sprocket 31. This is accomplished by providing a dog-bone shaped pair of members 62 with open end portions 64 through which the chain 16 passes going into the sprocket and coming out of the sprocket. The lower dog-boned elements serve to not only lead and strip the chain, but also tend to clean the chain of dirt and other foreign matter. What dirt and foreign matter is not cleaned from the chain, often packs within the hoist. The crescent-shaped, open-ended chain retaining plates 61 permit such foreign matter to drift into the sprocket chamber 65 (see FIG. 2). In the case of dirt and mud, it will often dry and pulverize in this sprocket chamber 65, and migrate on back out through the sprocket end and lead-in and stripper assembly. Because of the bilaterally symmetrical nature of the chain guide assembly 60, it is held within the chamber 65 by means of the single stripper bolt 66 and a pair of stripper plate bolts 68 and stripper plate spacers 69.

The safety brake drum 29 orientation at the end of the pinion drive shaft 25, was discussed above. Because of the central location of the brake drum 29 (see FIGS. 6 and 7), suflicient space exists within the auxiliary housing 50 to orient the safety brake assembly 30 in a high and dry position. The safety brake assembly 30 is unique in that the brake drum is in the form of a V-belt pulley (see particularly FIG. 3). The drum is flanked by a pair of brake shoes 70 secured for pivotal action by the brake shoe pin 71 at one end. The brake shoe jaws 72 are traversed by a brake shoe retainer bolt 74, locked by means of a nut 75 and spring-loaded by spring 76, to constantly urge the jaws 72 centrally, thereby urging the brake lining 78 against the drum 29. The safety brake is actuated by solenoid 80, which is coupled to the motor in such a manner that the solenoid lowers the brake arm 81 when the motor starts. As the brake arm 81 is lowered by the solenoid 80, the brake shoe activating cam portion 82 of the brake arm 81 pivots about the brake arm pivot pin 84. The brake arm cam 82 then urges the jaws 72 apart as the brake shoe threaded cam followers 85 are engaged. This action, of course, releases the brake lining 78 from the brake drum 29 and permits the motor drive shaft to rotate and drive the sprocket 31. When the power is off the motor, the solenoid releases the brake arm 81, and the spring-loaded jaw retainer 74 squeezes the jaws 72 shut, and the brake lining 78 engages the drum 29. As will be particularly seen in FIG. 6, an unusually compact and small arrangement is achieved due to the orientation of the drive shaft 25 and the proportioning of the safety brake with the solenoid 80 at one end and the brake shoe jaws 72 at the opposite end. By employing a V-type pulley 29, the brake size and weight are reduced substantially Without reducing its effectiveness.

Also, the unique orientation of the brake drum 29, provides space for locating the limit switch assembly 35, as best illustrated in FIG. 6. The limit switch assembly 35 contemplates a limit switch drive shaft 32 with a long threaded portion 86 which engages a pair of nylon nuts 88. The nylon nuts 88 have a plurality of peripheral slots 89, a pair of which are oriented to engage the guide rail 90. As the sprocket 31 rotates, the limit switch drive shaft 32 rotates a similar number of revolutions. The nylon nuts 88, migrate to the left or right along the threads 86, depending upon which direction the hoist is operating. When the nuts proceed all the way to the left, the contact points 91 are activated and the switch stops. Similarly, when the nuts proceed all the way to the right, the contact points 92 are engaged and the motor is stopped. By providing separate drive shafts from the sprocket and the motor, which bear a spaced relation to each other, the limit switch and the safety brake can both be oriented in the auxiliary housing 50 in adjacent positions for simultaneous inspection and adjustment, without extensive disassembly of the hoist.

It will be noted that the hoist is suspended by means of ahook 95, the shank 96 of which has an end collar 98 which anchors the hook 95 between the split halves of the sprocket housing. The chain at one end is secured by means of a bolt assembly 99 to the housing, and at another end may be optionally secured by a deadend bolt 100 (see FIG. 2), also to the housing.

The bearings 1, 102 and 103 on the motor drive shaft are ball bearings and of a sealed type construction to prevent the migration of grease and oil along their journalled shafts. The housings are preferably cast, and provided with suflicient ribbing to permit thin walled sections, thereby reducing the weight of the hoist.

In review, it will be seen that a power hoist with a unique power train has been disclosed. The sprocket or lifting wheel drive shaft, is in spaced parallel relationship with the motor drive shaft. At the terminal ends of both the lifting means drive shaft and motor drive shaft, provision is made for respectively securing the limit switch assembly and safety brake assembly. The speed reducing gear train which transmits the rotary motion from the motor drive shaft to the sprocket or lifting wheel, because of the unique spacing of the two drive shafts, may be readily converted to double or one-half speed. In addition, the particular orientation of the power train permits a compartmentalization within the hoist, which makes servicing in the field easy and efficient, and which also serves to isolate grease and other foreign matter in those areas where the construction of the hoist most readily can accommodate such materials.

Although particular embodiments of the invention have been shown and described in full here, there is no intention to thereby limit the invention to the details of such embodiments. On the contrary, the intention is to cover all modifications, alternative embodiments, usages and equivalents of the power-driven hoist, as fall within the spirit and scope of the invention, specification, and appended claims.

I claim as my invention:

1. A power-driven hoist comprising, in combination, a motor, a motor drive shaft, a safety brake drum driven by the end of the motor drive shaft and coaxial therewith, a lifting drum parallel with and below the motordriven shaft, a lifting drum drive shaft coaxial with the lifting drum, a limit switch below the safety brake drum driven by and coaxial with the lifting drum drive shaft, an interchangeable spur gear train interposed between the motor-driven shaft and lifting drum drive shaft to reduce the speed of the lifting drum below that of the motor, and a housing for said hoist having a wall separating the safety brake drum and limit switch from the other elements of the hoist.

2. A power-driven hoist comprising, in combination, a motor, a motor drive shaft, a safety brake drum driven by the end of the motor drive shaft and coaxial therewith, a chain sprocket parallel with and below the motor-driven shaft, a sprocket drive shaft coaxial with the sprocket, a limit switch below the safety brake drum driven by and coaxial with the sprocket drive shaft, an interchangeable spur gear train interposed between the motor-driven shaft and sprocket drive shaft to reduce the speed of the sprocket below that of the motor, a four-compartment housing including a motor compartment, a sprocket compartment, a gear train compartment, and an auxiliary system compartment, each of said compartments having an end wall, said end walls having hearings to journal the motor-driven shaft and the sprocket drive shaft at their respective maximum load ends, the auxiliary system compartment being at one end of the hoist and housing the safety brake drum and limit switch, and the motor compartment being at the opposite end of the hoist from the auxiliary system compartment.

3. A power-driven hoist comprising, in combination,

a motor, a motor drive shaft, a safety brake drum driven by the end of the motor drive shaft and coaxial therewith, a lifting drum parallel with and below the moton' driven shaft, a lifting drum drive shaft coaxial with the lifting drum, a limit switch below the safety brake drum driven by and coaxial with the lifting drum drive shaft, a gear train interposed between the motor-driven shaft and lifting drum drive shaft to reduce the speed of the lifting drum below that of the motor, and a four-compartment housing including a motor compartment, a lifting drum compartment, a gear train compartment, and an auxiliary system compartment, each of said compartments having an end wall, said end walls having bearings to journal the motor-driven shaft and the lift ing drum drive shaft, the auxiliary system compartment being at one end of the hoist and housing. the safety brake drum and limit switch, and the motor compartment being at the opposite end of the hoist from the auxiliary system compartment thereby permitting ready access to the motor and auxiliary systems for repair and adjustment without disassembling the lifting drum drive and gear train assemblies.

4. A power-driven hoist comprising, in combination, a motor, a motor drive shaft, a safety brake drum driven by the end of the motor drive shaft and coaxial therewith, a sprocket parallel with and below the motordriven shaft, a sprocket drive shaft coaxial with the sprocket, a limit switch below the safety brake drum driven by and coaxial with the sprocket drive shaft, a gear train interposed between the motor-driven shaft and sprocket drive shaft to reduce the speed of the sprocket below that of the motor, said gear train including a motor drive shaft pinion, a sprocket gear, a sprocket gear pinion and sprocket gear pinion gear combination, an interchange gear and pinion combination, said gears being proportioned and oriented on centers so that the interchange gear and pinion can be removed and the sprocket gear pinion gear enlarged to drive directly from the drive shaft pinion, thereby doubling the sprocket speed.

5. A power-driven hoist comprising, in combination, a motor, a motor drive shaft, a safety brake drum driven by the end of the motor drive shaft and coaxial therewith, a chain sprocket parallel with and below the motordriven shaft, a sprocket drive shaft coaxial with the sprocket, a limit switch below the safety brake drum driven by and coaxial with the sprocket drive shaft, a gear train interposed between the motor-driven shaft and sprocket drive shaft to reduce the speed of the sprocket below that of the motor, and a four-compartment housing including a motor compartment, a sprocket compartment, a gear train compartment, and an auxiliary sys tem compartment, each of said compartments having an end wall, said end walls having bearings to journal the motor-driven shaft and the sprocket drive shaft, the auxiliary system compartment being at one end of the hoist and housing the safety brake drum and limit switch, and the motor compartment being at the opposite end of the hoist from the auxiliary system compartment, the motor drive shaft having interrupted splined ends within the sprocket compartment, and a splined sleeve coupling the interrupted ends so the motor can be removed without entering the sprocket compartment.

6. A power-driven hoist comprising, in combination, a motor, a motor drive shaft, a safety brake drum driven by the end of the motor drive shaft and coaxial therewith, a chain sprocket parallel with and below the motor-driven shaft, :1 sprocket drive shaft coaxial with the sprocket, a limit switch below the safety brake drum driven by and coaxial with the sprocket drive shaft, a gear train having a motor-driven shaft gear and a sprocket drive shaft gear interposed between the motor-driven shaft and sprocket drive shaft to reduce the speed of the sprocket below that of the motor, a four-compartment housing including a motor compartment, a sprocket compartment, a gear train compartment, and an auxiliary system compartment, each of said compartments having an end wall, said end walls having bearings to journal the motor-driven shaft and the sprocket drive shaft, the auxiliary system compartment being at one end of the hoist and housing the safety brake drum and limit switch, and the motor compartment being at the opposite end of the hoist from the auxiliary system compartment, the drive shaft having interrupted splined ends Within the sprocket compartment, a splined sleeve coupling the interrupted splined ends so the motor can be removed without entering the sprocket compartment, removable means locking the safety brake drum on the end of the motor-driven shaft, and interlocking means at the end of the sprocket drive shaft attaching the sprocket drive shaft to the sprocket drive shaft gear so that all of the auxiliary parts plus the motor can be removed without entering the sprocket compartment or gear train compartment.

7. A power-driven hoist comprising, in combination, a motor, a motor drive shaft, a safety brake drum driven by the end of the motor drive shaft and coaxial therewith, a chain sprocket parallel with and below the motor driven shaft, a sprocket drive shaft coaxial with the sprocket, a limit switch below the safety brake drum driven by and coaxial with the sprocket drive shaft, a gear train interposed between the motor-driven shaft and sprocket drive shaft to reduce the speed of the sprocket below that of the motor, a four-compartment housing including a motor compartment, a sprocket compartment, a gear train compartment, and an auxiliary system compartment, each of said compartments having an end wall, said end walls having bearings to journal the motor-driven shaft and the sprocket drive shaft, the auxiliary system compartment being at one end of the hoist and housing the safety brake drum and limit switch, and the motor compartment being at the opposite end of the hoist from the auxiliary system compartment, said motor drive shaft having interrupted splined ends within the sprocket compartment, and a splined sleeve coupling the interrupted ends so the motor can be removed Without entering the sprocket compartment, said splined sleeve traversing the width of the sprocket compartment.

References Cited in the file of this patent UNITED STATES PATENTS 1,945,712 Wadd Feb. 6, 1934 2,244,221 Schroeder June 3, 1941 2,342,091 Schroeder Feb. 15, 1944 2,368,039 Parker Jan. 23, 1945 2,496,754 Schramm et a1 Feb. 7, 1950 2,570,833 Metcalf et al. Oct. 9, 1951 2,667,331 Robins et a1 Jan. 26, 1954

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