US2477783A

US2477783A - Hoist

Info

Publication number: US2477783A
Application number: US545987A
Authority: US
Inventors: William H Britt
Original assignee: Columbus McKinnon Chain Corp
Current assignee: Columbus McKinnon Chain Corp
Priority date: 1944-07-21
Filing date: 1944-07-21
Publication date: 1949-08-02
Anticipated expiration: 1966-08-02

Description

Patented Aug. 2, 1949 NT OFFICE HOIST William H. Britt, Tonawanda, N. Y., assignor to Columbus McKinnon Chain Corporation, Tonawanda, N. Y

Application July 21, 1944, Serial No. 545,987

1 Claim.

This invention relates to chain hoists, and more particularly to relatively high speed hoists employing load chains of the looped link type and relatively small diameter chain driving wheels of the so-called pocket wheel type.

One of the objects of the invention is to provide an improved high speed hoist of the type referred to which is adapted to employ a chain wheel of decreased diameter and which is at the same time less subject to vibration or shimmy efieets such as are usually induced by the load chain movement about the chain wheel, than comparable hoists ofthe prior art.

Another object of the invention is to provide improvements in hoists of the character referred to so as to enable such hoists to be constructed of reduced dimensions and improved overall compactness and of reduced weight and mechanical complications.

Another object of the invention is to provide in chain hoists improved means for eliminating relative oscillation of the hoist frame and the load chain such as normally occurs because of variances of the lateral distance between the axis of rotation of the chain wheel and the vertical center line of the load chain clue to eccentric movements of the chain links While meshing and unmeshing relative'to the drive wheel. Other objects and advantages of the invention appear in the specification hereinafter.

In the drawing:

Fig. 1 is a vertical section through a chain hoist frame showing, fragmentarily, the load chain in operative position relative to a chain control device of the invention;

Fig. 2 is a fragmentary section taken along line 11-11 of Fig. l; and

Fig. .3 is an elevation of the pocket wheel element thereof in disassembled relation.

The drawing illustrates byway of only one example an application of the invention to a chain hoist of generally standard form which includes a circular frame it adapted to be suspended from a carrying hook screwthreaded into connection with the frame at a threaded apertured portion 52 thereof. The frame it rotatably mounts a load chain drive wheel l5 which it will be understood may be carried by any suitable bearing devices at opposite sides of the hoist frame, as is generally customary in the art. The wheel i5 is illustrated to be of the so-called pocket wheel type; that is, being recessed toprovide chain link receiving pockets at intervals about its periphery; said pockets terminating parallel bottom lands lfi-IE at opposite sides of a grooved center portion l8 of the wheel. Thus, the wheelltl is adapted to mesh .in geared relation with alooped link chain such as is illustrates in Fig. l to comprise alternate -edgewise-disposed chain links. 253 and flatwise-disposed links .22; the terms edgewise and flatwise being employed to refer to the attitudes of the links relative to the peripheral surface of the driving wheel. Thus, the inner side portions of the edgewisedisposed links 2i! are received between the parallel lands it-l6 of the wheel 15 while the fiatwisedisposed links 22 are received within the complementary shaped pockets provided by the land surfaces it-l6 to end-butt at opposite sides of the intermediate projecting teeth portions 24 of the wheel so as to be thereby geared to the drive wheel l5. It is to be understood that the pocket wheel and chain drive arrangement of the drawing as described aforesaid is previously old in the art, and constitutes a part of the present invention only when employed in combination with a chain control devlcezsuch as will be hereinafter described.

Chain drive -ar:rangements of the prior art as referred to hereinabove are inherently subjected to the vibration-inducing effects of eccentric movements of the chain links relative to the axis of rotation of the drive wheel as explained hereinabove. .Thisis because the articulated flat link constructionoi the chain prohibits the latter from training about a wheel in such manner as to assume a smoothly curving center line as suggested diagrammatically at 25. it is inevitable that :as thewheel rotates to drive the chain, diiferent'portions of the links are disposed atdirferent distances from the axis of the wheel rotation. Consequently, the point of vertical suspension of the load chain oscillates laterally as the wheel rotates, and therefore whereas at one position of the wheel the load carryingstrand of the hoist chain will tend to hang vertically from the wheel about a center line such as 1s indicated at 38, at another position of rotation of the wheel the load strand :of the chain will tend to hang fromrthe hoist frame about a center line such as is indicated at 32. Thus, whenever the hoist is operating upon a, load suspended from the lower end of the left hand chain strand as viewed in Fig. 1, the constantly shifting relation of the chain support center line relative to the axis of the wheel results in lateral oscillations of the hoist frame relative to a center line intersecting the center of hoist suspension and the center of gravity of the load; and whenever a hoist of this type is operated at relatively high speed such oscillations introduce serious vibration effects upon the hoist system at frequencies determined by the number of pockets in the wheel and its speed of rotation. The amplitudes of such oscillations depend of course upon the size of the chain links and the size of the wheel, and increase as the number of pockets in the wheel is decreased. Therefore, it will be appreciated that whereas in the interests of mechanical simplification and reduction of overall hoist size and weight it has always been desired to minimize the required speed reduction ratio to the drive wheel through use of reduced diameter wheel operating at increased speeds, such changes would have involved corresponding increases in amplitudes and frequencies of the oscillation effects referred to hereinabove such as could not be tolerated.

With the advent of increasing demands for light-weight high-speed reduced-size hoists of the looped link chain type it is imperative that this problem of oscillation or shimmying be solved; and the present invention contemplates a chain motion control device to be mounted upon the hoist frame in such manner as to eliminate such tendencies to shimmy as above referred to. It is contemplated that the control device of the invention be so provided as to control both the edgewise and flatwise links of the chain and to provide continuous correction for the oscillation tendency as distinguished from only intermittent correction thereof. The invention also contemplates provision of a chain link control device as referred to hereinabove which operates automaticall to snug the chain against the chain drive wheel whereby to keep it more firmly in gear while at the same time cooperating in improved manner with the usual chain stripper device such as is customarily employed adjacent the drive wheel; and in any case to provide a total reduction of the required head room or vertical dimension in the hoist frame structure.

More specifically, as shown in the drawing by way of example only, the chain control device comprises a roller designated generally at 40 which is fitted with a bushing 42 and is rotatably mounted upon a stub shaft 44 extending transversely of opposite side wall portions 46-41 of the hoist frame 10. The roller 40 is centrally grooved as at 48 and thus presents peripherally thereof parallel raised lands Ell-50 which are adapted to receive in flatwise bearing relation thereon the links 22; while the edgewise presented links 20 are received within the grooved portion 48 of the roller to be guided and preferably pressed against by the bottom circular land of the grooved portion of the roller. Thus, the roller 40 is adapted to control the load chain in improved manner because both the edgewise and flatwise links of the load chain are so controlled by the roller 40 as to maintain the chain center line at the point of delivery thereof relative to the hoist to be constantly coincident with the vertical load center line as indicated at 32 in Fig.

Thus, the control roller 40 of the invention provides for reception and delivery of the load chain to and from the hoist structure at a uniform distance from the axis of rotation of the drive wheel 15, while at the same time the control roller 40 operates to snug the chain toward the drive wheel 15 without interfering with the action of the customarily used stripper block in separating the chain from the wheel during hoisting operations. It will of course be appreciated that in lieu of the roller construction shown and described hereinabove the chain control element of the invention may in some cases comprise a suitably grooved block or the like stationarily mounted upon the hoist frame at a position similar to the location of the roller 49 so that the chain may slide over and through the block to be guided thereby to maintain a constant delivery point relative to the hoist frame and to be snugged toward the chain drive wheel, as explained hereinabove; and that although only one form of the invention has been shown and described in detail it will be apparent to those skilled in the art that the invention is not so limited but that various changes may be made therein without departing from the spirit of the invention or the scope of the appended claim.

I claim:

A power driven relatively high speed chain hoist comprising a frame having a support axis, a pocket wheel driver having a small number of pockets, said driver being rotatably supported in said frame, a looped link load chain having a load strand thereof engageable with and depending from said driver, each of said pockets having varying radii which tend to subject said strand to relative horizontal displacement as said driver rotates, and a strand stabilizing and guiding member carried by said frame below said driver and horizontally spaced from said driver whereby surfaces of said driver and member engage opposite surfaces of said strand, the strand engaging surface of said strand stabilizing and guiding member being horizontally spaced from said pocket wheel axis a distance not greater than the minimum of said radii plus the maximum horizontal dimension of said strand, whereby said strand below said member is maintained stabilized substantially coincident with said support axis.

WILLIAM H. BRIT'I.

REFERENCES CITED The following references are of record in th file of this patent:

UNITED STATES PATENTS Number Name Date 419,852 Hambay Jan. 21, 1890 577,330 Speidel Feb. 16, 1897 676,931 Barrett June 25, 1901 2,274,280 Stinson Feb. 24, 1942 2,335,571 Schroeder Nov. 30, 1943