US3075618A - Actuating mechanism for hoisting machine - Google Patents

Description

Jan. 29, 1963 s. T. BUCK 3,075,618

ACTUATING MECHANISM FOR I-IOISTING MACHINE Filed July 22, 1960 5 Sheets-Sheet 1 fi IN V EN TOR.

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Jan. 29, 1963 S. T. BUCK ACTUATING MECHANISM FOR HOISTING MACHINE Filed July 22, 1960 5 SheetsSheet 2 o o O 51 O INVENTOR. Srsmqzo 7. Buzz,

ATTORNEYS.

Jan. 29, 1963 s. T. BUCK 3,075,618

ACTUATING MECHANISM FOR HOISTING MACHINE Filed July 22, 1960 3 Sheets-Sheet 3 s N k k 1 I 3) J I77. A Qr- I: N. z: N a; g

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BY 577. Am 7. Eve/c, flay/ ATTORN 5V5- United States Patent'O 3,075,618 ACTUATING MECHANISM FOR HOISTING MACHINE Steward T. Buck, Buck Equipment Corp, 720 Anderson Ferry Road, Cincinnati, Ohio Filed .Iuly 22, 1960, Ser. No. 44,599 11 Claims. (Cl. 187-32) This invention relates to hoisting machines of the type used on construction jobs and the like to raise supplies and equipment to the upper stories of a building or other elevated work site. While such hoisting machines may take various forms, they usually comprise a tower provided wit-h vertically extending guideways or tracks along which a lift platform is adapted to be moved, the lift platform being raised and lowered by means of a cable one end of which is wound on the drum of a hoist having a prime mover and clutch mechanism for selectively rotating the drum in opposite directions to raise and lower the lift platform.

In my copending application Serial No. 761,186, filed September 15, 1958, and entitled Automatic Control Sys tern for Hoisting Machine, I have taught the provision of a hoisting machine of the general type just characterized which incorporates an automatic control system for starting and stopping the lift platform at predetermined upper and lower positions, the machine operator having only to start the platform on its upward or downward journey whereupon the control system, which is electrically controlled, takes over to stop the lift platform at a pre-set position. While such automatic system has proven to be highly successful, the mechanism is nevertheless relatively expensive and there is a decided need in the industry for a less expensive, preferably non-electronic mechanism for controlling the up and down movement of the lift platform.

Accordingly, a principal object of the instant invention is the provision of actuating and control mechanism for a hoisting machine which is of relatively simple and inexpensive construction and yet enables the operator to pre-set the level at which the lift platform will be stopped, thereby relieving him for other duties.

A further object of the instant invention is the provision of actuating and control mechanism for a hoisting machine which is positive in action and in which mechanical means are employed to control the starting and stopping of the hoist mechanism to the elimination of the more costly electronic controls of the system taught in the aforementioned application.

The foregoing together with other objects of the invention which will appear hereinafter or which will be apparent to the skilled worker in the art upon reading these specifications, I accomplish by that construction and arrangement of parts which I shall now describe in exemplary embodiments.

Reference is now made to the figures of the drawings wherein:

FIGURE 1 is a side elevational view of a portable hoisting machine with the tower in its elevated position.

FIGURE 2 is an enlarged fragmentary plan view of the selector disc for selectively engaging the clamps on the control cable.

FIGURE 3 is a side elevational view with certain parts shown in dotted lines of the selector disc assembly of FIGURE 2.

FIGURE 4 is a plan view of the hoist mechanism showing the clutch and brake assembly together with its actuating means.

FIGURE 5 is an enlarged fragmentary and elevational view of the clutch and brake mechanism and the cam means for actuating them.

3,075,618 Patented Jan. 29, 1963 ICC FIGURE 6 is an enlarged side elevational view with parts broken away of the brake shoe assembly, illustrating the manner in which it is actuated by the cam means.

FIGURE 7 is a vertical cross sectional view illustrating the general layout of the clutch and brake mechanism.

FIGURE 8 is an enlarged side elevational view of the cam Wheel which control the position of the cam shaft and cam segments for actuating the brake and clutch shoes.

FIGURES 9 and 10 she side elevational views of brake and clutch actuating cams.

Referring first to FIGURE 1 of the drawings, I have therein illustrated a portable hoisting machine with which the actuating mechanism of the instant invention may be employed. Essentially, the machine comprises a base or frame 1 mounting a vertically extending tower 2 along which the lift platform or other lifting means 3 is adapted to travel, the lift platform having grooved rollers 4 adapted to move along guide rails or tracks 5 forming a part of the tower structure. The lift platform is adapted to be raised and lowered, as from the position shown in solid lines at the bottom of the figure to the position shown in dotted lines at the top thereof, by means of a lift cable 6 which extends upwardly from the hoist mechanism 7 around a pulley 8 at the top of the tower and then downwardly for attachment to the lift platform. The base or frame 1 of the device may be provided with retractable wheels 9 'by means of which the device may be readily transported from place to place; and to facilitate such transportation, the tower is preferably formed as a plurality of hinged sections joined together by means of hinges 10. Collapsible towers of this character are disclosed in my Patent No. 2,653,685 dated September 29, 1953 and entitled Portable Hoisting Tower, and reference is made to the patent for details of the construction and mode of erecting and collapsing the tower structure. However, it should be understood from the outset that the particular form of tower structure does not constitute a limitation upon the instant invention since the actuating mechanism to be hereinafter described is applicable to diverse types of devices, whether they be of portable character or erected on the job in a piece by piece assembly.

Referring now to FIGURE 4, the base or frame 1 mounts a prime mover 11, which generally comprises an internal combustion engine the drive shaft of which is operatively connected, as by means of the chain drive 12, to the hoist mechanism 7 which includes a drum shaft 13 to which the drum 14 for the lift cable 6 is secured. The shaft 13 also mounts a clutch mechanism 15 operatively connected to the chain drive 12; and a brake mechanism 16 is also provided for locking the cable drum 14 against rotation. If desired, the drum shaft 13 may also be provided with a power take-off 17 and/or a work head 18.

The actuating and control mechanism for the hoist comprises a cam shaft 19 provided at one end with a control wheel 20 and its opposite end with a control cam 21 by means of which the cam shaft may be releasably secured in its various positions of use. The cam shaft 19 mounts a series of cams, which will be described in detail hereinafter, by means of which the brake mechanism I6 is engaged and released and the clutch mechanism 15 activated to either raise or lower the lift platform depending upon the direction of rotation of the cable drum 14.

Essentially, the cam shaft 19 has three positions of use. The first comprises an intermediate or neutral position in which the brake mechanism 16 is locked and both the up and down components of the clutch mechanism 15' are disengaged. From the neutral position, the cam shaft may be rocked in either a clockwise or a counter-clockwise manner; rotation or rocking movement in one direction serving to engage the up component of the clutch mechanism while at the same time releasing the brake, whereas rocking movement in the opposite direction serves to engage the down component of the clutch mechanism and also serves to release the brake. Rocking movement of the cam shaft is effective by mean of a control cable 22 secured to the control wheel 20.

As seen in FIGURE 1, the control cable 22 extends from control wheel 20 to a pulley wheel or sheave 23 located 'at the lower end of the tower 2 adjacent the lift platform 3, the cable then extending upwardly along the tower in close promixity to the path of travel of the lift platform, the control cable passing around one or more pulley wheels 24 at the upper end of the tower and then returning downwardly to the control wheel 20. Preferably, the control cable 22 is in the form of an endless band one portion of which is wrapped about a periphery of the control wheel-which may be grooved for this purposethe cable being cleated or otherwise fixedly secured to the control wheel. With this arrangement, the control cable will have a limited movement in opposite directions, the extent of such movement being determined 'by the degree of rotative movement required to move the cam shaft 19 from the neutral position to either of the operating positions. It will be apparent that the control wheel 2% may be turned so as to rock the cam shaft by engaging and pulling on the control cable at any point along its length.

Spaced along that portion of the control cable which parallels the path of travel of the lift platform 3 are a plurality of cable clamps 25, which are of successively larger diameter, with the smallest diameter clamp 25a "lowermost and the successively larger diameter clamps 25b 25c and 25d spaced upwardly along the control cable. These clamps are adapted to be selectively engaged by a cable follower 26 mounted on the lift platform 3, the cable follower surrounding and moving along the control cable as the lift platform moves up and down along the tower. As best seen in FIGURES 2 and 3, the cable follower 26 is provided with a mounting arm 27 by means of which it may be readily secured to the lift platform, the follower being provided with an irregular slot 28 through which the control cable is adapted 'to be passed, the inner end of the slot 28 terminating in an annular opening 29 through which the several cable clamps 25 may freely pass, with the possible exception of the uppermost cable clamp 25d. The cable follower also mounts a rotatable selector disc 30 having a pinrality of open'ings 31 therein of successively larger diameter adapted to be selectively juxtaposed to the opening 29. It will be noted that each of the openings 31a, "31b, 31c and 31d has a neck portion 32 opening outwardly to the periphery of the selector disc 30, the neck portions 32 being arranged to be aligned with the irregu- -l-ar' slot 23 so that the control cable may be initially intro- 'duced-therein, whereuponthe necks 32 may be offset with respect to the slot 28, as will be clear from FIGURE 2, thereby assuring retention of the control cable within the confines of the selected opening 31. A spring biased detent 33 is preferably provided coacting with depressions 34 in the unde'rsurface of the disc 30 to align the several openingslfl with respect to the opening 29.

The diameter of the openings-31 are correlated to the diameters of the cable clamps 25 so as to pass or stop the cable clamps as the lift platform moves along the tower with the cable follower in engagement with the control cable.

In the embodiment illustrated there are four cable clamps and four openings in the selector disc. The smallest opening 31a in the selector disc is of a diameter smaller than the diameter ofthe lowermost cable through the opening 31a and continued upward movement of the lift platform will draw the cable with it, thereby causing the control wheel 20 to be rotated. Such rotation acts to disengage the up component of the clutch and set the brake, thereby arresting the upward movement of the lift platform at'a predetermined elevation. It will be understood, .of course, that such predetermined elevation may be varied -by adjusting theposition of the cable clamps 25 along the control cable 22. If the lift platform is to be raised to the position established by the cable clamp 25c,'then the selector disc will be set so that the opening 31c surrounds the cable. The diameter of the opening 310 is such that it will permit the lowermost cable clamp 25a to pass freely therethrough, as will the next cable clamp 2512; but the cable clamp 250 will be engaged and retained, whereupon the cable willbe lifted to disengage the up component of the hoist mechanism.

It will be understood that the upward movement of the lift platform 3 will be initiated by rocking the cam shaft 19 to clutch engaging position. This may be done by means of a hand grip 35 secured to the return flight of the control cable 22 in a position where it may be readily grasped by the machine operator. If desired, the opposite end of the cam shaft 19 may be provided with a second control wheel 36' which may be utilized to actuate the hoist mechanism from the opposite side of the machine. Such second'controlwheel may be provided with a crank handle 37 and, if desired, a second control cable 22a may extend upwardly from the control wheel 36 in much the same manner as the cable 22, although the sec- *ond cable need not be provided with the cable clamps 25.

From the foregoing it should be apparent that the downward movement of the lift platform may be controlled in similar fashion to the upward movement thereof by suitably adjusting-theselector disc to either pass or stop the various cable clamps. The bottom or down position of the lift platform may be permanently fixed by means of a cable clamp 2512 which will bed a diameter larger than any of the openings 31 in the selector disc.

As'seen in FIGURE 3, the cable clamps 25 will'prefcrably have a cylindrical center portion 38 terminating in conical end portions 39 by means of which the clamps will be guided through the openings 29 and 31. In the case of the clamps defining'the upper and lower limits of travel, the conical portions 39v facing the openings may be eliminated since at no time do these clamps pass through the selector disc.

it is also desirable to provide the selector disc assembly with a manually controlled cable locking device to prevent accident-ail actuation of the control mechanism. To "this end, the cable follower 26 may mount a block 40 to which an arm 41 is slidably secured, the arm being movable horizontally from the position illustrated in solid lines in FIGURE '3 to-the position illustrated in dotted lines. The arm 41 is provided with a generally V-shaped notch 42 which, whenthe armisin the extended position, receives the control cable 22 and overlies the cable clamp 25 engaged by the selector disc. The cable clamp is thus effectively retained between the selector disc and the arm and movement of the cable is prevented. Thus, if a person loading it. The arm 41 may be conveniently actuated by means of a' finger grip43, the arm having an elongated slot 44 therein movable relative to the studs-45 and retained in the rettr-acted'or extended position by means of spring detent "46 engageable in depressions or the like 47 in the undersurface of the arm.

Referring now to FIGURE 7 of the drawings, the clutch :mechanism 15 comprisesa planetarylgear system of known character having a clutch wheel-I50 forming a partof the down component of the system, and a rotatable housing 51 forming a part of the up component of the system. A clutch band 52 surrounds the clutch wheel 56 and a similar clutch band 53 surrounds the rotatable housing 51, the clutch bands acting in a manner to be fully explained hereinafter to selectively lock the clutch wheel and/or housing against rotation or free them for rotation, depend- :ing upon the direction in which the drive shaft 13 is to be driven.

The shaft 13 is driven by means of the sun gear 54 which is keyed to the shaft and positioned for engagement with the gear clusters 55 and 55a each of which is cornposed of three gears keyed together for joint rotation about their common shafts 56 and 56a mounted in the rotatable housing 51. An end-most gear in each cluster is in meshing engagement with sun gear 54, whereas the intermediate gear of each cluster is in engagement with a gear head 57 secured to a rotatable sleeve 58 the opposite end of which mounts a sprocket 59 which is engaged by the chain drive 12 from the prime mover 11. The remaining gear in each cluster engages the gear head on secured to the hub 61 of the clutch wheel 59, the hub 61 being mounted for rotation relative to the sleeve 58 which it surrounds.

With the arrangement just described, the shaft 13 will remain stationary when both clutch wheel 5% and housing 51 are free to rotate, i.e. when the clutch bands 52 and 53 are disengaged. However, when the clutch band 52 is contracted so as to engage and secure the clutch wheel 50 against rotation, the sun gear 54 will be rotated in one direction due to the action of the gear clusters. When, on the other hand, the housing 51 is held against rotation and the clutch wheel 56) is free to rotate, the gear head 57 will act through the intermediate gear in each cluster to drive the sun gear in the opposite direction. Normally, the clutch wheel 50 comprises the down component of the gear system and the rotatable housing 51 comprises the up component. Thus, when the rotatable housing 51 is held against rotation, the lift cable will be wound onto the drum 14; whereas when the clutch wheel so is held against rotation, the cable will be payed out from the drum.

It will be noted from FIGURE 7 that one end of the drum 14 comprises a drum flange 6-2 the periphery of which defines a brake drum 63 coacting with a brake band 64. The brake band is adapted to enga e the brake drum 63 and lock the cable drum 14 against rotation when the clutch components are both released, i.e. when the actuating mechanism is in the neutral position. However, when the actuating mechanisn1-which comprises the cam shaft 19, and the control wheel 26 and the control cam 21- is moved to either of the operating positions to thereby engage one or the other of the clutch bands 52, 53, the brake band 64 will be disengaged so as to free the cable drum for rotation.

As a practical matter, the clutch bands 52, 53 and the brake band 64 are of identical construction and, as will be evident from FIGURES 5 and 6, are actuated by identical mechanism. Thus, as possibly best seen in FIGURE 6, each of the bands is composed of an upper shoe 65 and a lower shoe 66 each pivoted at one end to the shaft 67 by means of hinges 6-8. At their opposite ends the shoes 65 and 66 mount yoke adapters 69 to which the yokes 7t and 70a are adju-stably secured. Each pair of yokes 70 and 70a is joined together by -a pair of rods 7 ll, '72 provided with springs '73 surrounding the rods and arranged to urge the yokes towards each other, thereby clamping the shoes against the drum or wheel with which they are associated. Adjustment nuts 74 are provided to vary the compression of the springs 73 so that the clamping pres sure of the band may be adjusted as required. The bands are thus biased toward the contracted or set position by 'the springs 73 and are expanded or released by means of the cams mounted on the cam shaft 19, the cams being arranged, upon rotation of the cam shaft 19, to engage the cam followers 75, 75a mounted on the yokes in the manner seen in FIGURES 5 and 6.

The cam followers 75, 75a for each of thebands 52, 55 and 64 are positioned to engage cams 76, 77 and 73, respectively, mounted on cam shaft 19 and rotatable thereby. The brake cam '78 is illustrated in FIGURE 9; whereas FIGURE 10 illustrates one of the clutch cams, such as the cams 77, the two clutch earns being of identical configuration. The cam 78 will be positioned on the cam shaft 19 in such fashion that the set of cam followers 75, 75a will lie in the depressions 78a when the cam shaft is in its neutral position; and the clutch cams 76 and 77 will be arranged in such fashion that the cam followers will be contacted by the rise portions, such as the pertions 77a, when the cam shaft is rotated to neutral position.

The cam shaft 19 is maintained in its several positions of use by means of the control cam 21 which, as will be seen in FIGURE 8, is provided with a pair of spaced apart pockets 79 and 3t adapted to be engaged by a cam follower 81 mounted between the arms of a yoke 32, the arms of the yoke each having an elongated slot S3 therein through which the cam shaft 19 is arranged to pass, the arms of the yoke lying on opposite sides of the control cam 21. The yoke 82 is secured to an end plate 84 of a sleeve 85 which is telescopically received by a second sleeve 86 the lowermost end of which is closed by a plate 87 mounting an attachment ear 38. A compression spring 89 is enclosed within the telescoping sleeves 85 and 86, the spring serving to resiliently bias the cam follower 81 toward the periphery of the control cam 21. It will be understood that the attachment car '83 will be secured to a fixed mounting forming a part of the machine frame.

When the control shaft 19 i in its intermediate or neutral position, the cam follower 81 will ride along the intermediate segment 90 of the control cam, but when the cam shaft is rotated, the cam follower 81 will engage one or the other of the pockets 79, 80, thereby securing the cam shaft in the rotated position. However, when positive turning force is applied to the cam shaft, as when the control cable 22 is actuated, the resistance of spring 89 will be overcome and the cam follower 31 will be released from the pocket and the control cam 21 will be free to return to the neutral position.

As should now be apparent, the instant mechanism provides positive control over the operation of the device, the clutch and brake mechanism being controlled by movement of the cam shaft 19 which, in turn, is under the control of the control cable 22. Preferably, the positioning of the clutch cams 76 and 77 relative to the brake cam 78 will be such that the selected clutch band will be engaged slightly in advance of the release of the brake band, thereby assuring that the winch will at all times be under the positive control of one or the other of the components. Similarly, the brake band will be set to engage momentarily before the release of a given clutch band when the cam shaft is moved from the operative to the neutral position. As an added safety factor, it is preferred to provide a centrifugal clutch on the drive shaft of the prime mover, particularly where an internal combustion engine is employed, to control the downward speed of the lift platform under conditions of heavy load. Such clutch will serve as a brake on the engine should it tend to run away under the heavy load.

Modifications may be made in the invention without departing from its spirit and purpose. For example, if it is desired to control both the up and down move ment of the lift platform, that is, provide adjustable setting for the lift platform as it travels downwardly from the top of the tower, the control cable 22a at the opposite side of the tower could be provided with a set of clamps arranged in reverse order to those on control cable 22, i.e. smallest diameter clamp uppermost, and the lift platform provided with a second cable follower and selector assembly positioned for engagement by the cable 22a.

Other modifications will undoubtedly occur to the skilled worker in the art upon reading this specification, and consequently I do not intend to limit the invention excepting in the manner set forth in the claims which follow. What I desire to secure and protect by Letters Patent is:

1. In a hoisting machine having a vertical tower along which a lift platform is raised and lowered by means of a winch and cable, actuating mechanism for controlling the movement of said winch and cable, said mechanism comprising clutch means having an up component and a down component operatively connected to said winch, and also brake means operatively connected to said winch, the improvement which comprises control means for selectively actuating said brake and clutch means, said control means comprising a rotatable cam shaft mounting a plurality of cams arranged, upon rotation of cam shaft, to selectively engage and release said clutch and brake means, a control cable ex tending vertically along said tower in alignment with the path of travel in said lift platform, said control cable being operatively connected to said cam shaft so that lengthwise movement of said control cable will act to rotate said cam shaft, a plurality of cable clamps secured to said control cable at spaced apart intervals, and control cable engaging means associated with said lift platform for selectively engaging pre-determined clamps on said control cable as said lift platform moves up and down along said tower, whereby, upon engagement of a pre-determined clamp by said cable engaging means, said control cable will be moved lengthwise -to thereby actuate said clutch and brake means.

2. The device claimed in claim 1 wherein adjacent cable clamps are of progressively larger diameter, and wherein said control cable engaging means comprises an adjustable selector having a plurality of control cable receiving openings therein of progressively larger diameter.

3. The device claimed in claim 2 wherein said selec- 'tor comprises a rotatable disc, and wherein means are provided to releasably secure said disc in predetermined position.

4. The device claimed in claim 3 wherein said selector disc is mounted on a'cable follower having an opening therein of a diameter at least as great as the largest opening in said selector disc, and wherein an irregular 'slot opens into the opening in said cable follower, each of the openings in said selector disc having a neck portion adapted to be aligned with the said slot to permit which a lift platform is raised and lowered by means of a winch and cable, actuating mechanism for controlling the movement of said Winchand cable, said mechanism comprising clutch means having an up component and .a down component operatively connected to said winch,

and also brake means operatively connected to said winch, the improvement which comprises'control means .for selectively actuating said brake and clutch means,

said control means comprising a rotatable cam shaft mounting a plurality of cams arranged, upon rotation-of said cam shaft, to selectively engage and release said clutch and brake means, a control wheel at one end of said cam shaft, a control cable extending vertically along said tower in alignment with the path of travel of said lift platform, said control cable being operatively connected to said control wheel and arranged so that lengthwise movement of the control cable in either direction will act to rotate said control wheel and the cam shaft on which it is mounted, a plurality of cable clamps secured to said control cable at spaced apart intervals, control cable engaging means associated with said 'liftplatform for selectively engaging pre-determined clamps on said control cable as said lift platform moves up and down along said tower, a control cam mounted on said cam shaft, said control cam having a plurality of spaced apart pockets therein adapted to be selectively engaged by a cam follower, depending upon the direction of rotation of said cam shaft, whereby to releasably lock said cam shaft in a pre-determined position of use.

6. The device claimed in claim 5 wherein said control cable is an endless cable one portion of which is looped about said control wheel and fixedly secured thereto.

7. The device claimed in claim 6 wherein the cam follower for said control cam is spring biased toward the periphery of said control cam.

8. The device claimed in claim 7 wherein said control cam has an intermediate or neutral position in which said brake means is set and said clutch components are released, said control cam being movable in opposite directions to up and down positions in which said brake means is released and one or the other of said clutch components engaged, depending upon the direction-of rotation of said control cam, the pockets in said control cam being positioned to releasably retain said control cam in the up or down positions.

9. In a hoisting machine having a vertical tower along which a lift platform is raised and lowered by means of a winch and cable, a drive shaft for said winch, clutch means having an up component and a down component operatively connected to said drive shaft, means connecting said clutch mechanism to a prime mover, brake means operatively connected to said drive shaft, the up and down components of said clutch means each having an external clutch drum engageable by coacting pairs of clutch shoes, said brake means including a brake drum engageable by brake shoes, spring means normally biasing said clutch and brake shoes to drum engaging position, control means for selectively releasing said clutch and brake shoes, said control means comprising a rotatable cam shaft mounting a plurality of cams arranged, upon rotation of cam shaft, to selectively en- .gage and expand said clutch and brake shoes, a control cable extending vertically along said tower in alignment with the path of travel of said lift platform, said control cable being operatively connected to said cam shaft so that lengthwise movement of said control cable will act to rotate said cam shaft, a plurality of cable clamps secured to said control cable at spaced apart intervals, and control cable engaging means associated with said lift platform for selectively engaging pre-determined clamps on said control cable as said lift platform moves up and down along said tower, whereby, upon engagement of a pre-determined clamp by said cable engaging means, said control cable will be moved lengthwise to thereby actuate said clutch and brake shoes.

10. The device claimed in claim 9 wherein said cam shaft has an intermediate or neutral position in which said brake shoes are engaged and said clutch shoes are released, said cam shaft being movable in opposite directions to up and down positions in which said brake shoes are released and the said pairs of clutch shoes selectively released depending upon the direction of rotation of said cam shaft.

11. The device claimed in claim 10 wherein the contours of said clutch and brake shoe actuating cams are such that the clutch shoe willibe engaged slightly in ad- 10 vance of the a'elease of said brake shoes, and viceversa, 344,307 Grovan June 22, 1886 whereby said device will be at all times under the positive 1,023,857 Lathrop Apr. 23, 1912 control of either said brake means or said clutch means- 1,038,020 Sturm Sept. 10, 1912 1,586,768 Allen June 1, 1926 References Cited 1n the file of th1s patent 5 1,599,938 Zetteflund Sept 14, 1926 UNITED STATES PATENTS 2,001,674 Erickson May 14, 1935 264,745 Peare Sept. 19, 1882 2,653,685 Buck Sept. 29, 1953

Claims (1)

1. IN A HOISTING MACHINE HAVING A VERTICAL TOWER ALONG WHICH A LIFT PLATFORM IS RAISED AND LOWERED BY MEANS OF A WINCH AND CABLE, ACTUATING MECHANISM FOR CONTROLLING THE MOVEMENT OF SAID WINCH AND CABLE, SAID MECHANISM COMPRISING CLUTCH MEANS HAVING AN "UP" COMPONENT AND A "DOWN" COMPONENT OPERATIVELY CONNECTED TO SAID WINCH, AND ALSO BRAKE MEANS OPERATIVELY CONNECTED TO SAID WINCH, THE IMPROVEMENT WHICH COMPRISES CONTROL MEANS FOR SELECTIVELY ACTUATING SAID BRAKE AND CLUTCH MEANS, SAID CONTROL MEANS COMPRISING A ROTATABLE CAM SHAFT MOUNTING A PLURALITY OF CAMS ARRANGED, UPON ROTATION OF CAM SHAFT, TO SELECTIVELY ENGAGE AND RELEASE SAID CLUTCH AND BRAKE MEANS, A CONTROL CABLE EXTENDING VERTICALLY ALONG SAID TOWER IN ALIGNMENT WITH THE PATH OF TRAVEL IN SAID LIFT PLATFORM, SAID CONTROL CABLE BEING OPERATIVELY CONNECTED TO SAID CAM SHAFT SO THAT LENGTHWISE MOVEMENT OF SAID CONTROL CABLE WILL ACT TO ROTATE SAID CAM SHAFT, A PLURALITY OF CABLE CLAMPS SECURED TO SAID CONTROL CABLE AT SPACED APART INTERVALS, AND CONTROL CABLE ENGAGING MEANS ASSOCIATED WITH SAID LIFT PLATFORM FOR SELECTIVELY ENGAGING PRE-DETERMINED CLAMPS ON SAID CONTROL CABLE AS SAID LIFT PLATFORM MOVES UP AND DOWN ALONG SAID TOWER, WHEREBY, UPON ENGAGEMENT OF A PRE-DETERMINED CLAMP BY SAID CABLE ENGAGING MEANS, SAID CONTROL CABLE WILL BE MOVED LENGTHWISE TO THEREBY ACTUATE SAID CLUTCH AND BRAKE MEANS.

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