US2560499A - Cable tensioning means for hoists - Google Patents

Description

R. F. WARRY CABLE TENSIONINGMEANS FOR HOISTS 2 Sheets-Sheet 1 Filed July 16, 1949 m n w K N 0 m m n. W

3 1951 R. F. WARRY zfismw CABLE TENSIONING MEANS FOR I-IOISTS Filed July 16, 1949 2 Sheets-Sheet 2 Patented July 10, 1951 CABLE TENSIONING MEANS FOR HOISTS Reginald Frank Warry, Twickenham, England,

assignor to R. F. Warry Limited, London, England, a British company Application July 16, 1949, Serial No. 105,117 In Great Britain September 29, 1947 1-1 Claims. (01. 187-20) 1 This invention relates to hoists,- e. g., transportable hoists in which a tower or column carries a power unit driving a winch drum on which is wound a cable passed over guides or sheaves on the tower or column and anchored to a platform adapted to be drawn tip and lowered down the tower or column. With-such apparatus there is at present provided remote control means actuated by an operator to control the winding on of the cable to lift the platform and also to control the rate of unwinding of the cable to lower the platform. For example there is provided at the top of the column a forwardly overhanging arm which can'swing about a vertical axis pivot and over which arm is guided a depending pullrope by which an operator on the platform or an adjacent position can control a clutch and brake of the power unit, the arrangement being such that upon completely releasing the pull on the pull-rope the power unit is ole-clutched from the winch drum and the brake applied, a lever at the top of the column, and to which the pullrope is anchored, being located so that it is engaged by the platform to prevent over-running in the event of the operator omitting to slacken the pull-rope at the uppermost point of travel of the platform. Likewise by suitably controlling the tension on the pull-rope the operator can tie-clutch and partially brake the winch drum to lower the platform under control. However, it is found that frequently operators do not properly control the appropriate remote control 'me'ans e. g. do not relea'se the tension on the rope as soon as the platform reaches the bottom of the hoist with theresult the winch drum continues to rotate thus producing a slack in the cable whereby the cable does not lay properly about the drum and/or becomes entangled or wedged with one or more of the guides or sheaves. This often results in a cable becoming quickly frayed and worn, or deformed due to not laying properly about the drum.

The chief object of the present invention is to obviate the foregoing undesirable action on the cable. Another object of the invention is to provide means for readily adapting the eifective length of the cable to suit different heights of the tower so as to ensure a suitable length of cable being wound upon the winch drum, without having to change cables.

According to the present invention means is provided adapted in the event of the manually operated remote control means, such as e. g. the aforesaid pull-rope, not being controlled so as to arrest unwindingof the winch drum immediately the platform reaches its lower terminus,

to take up the surplus length of cable as it is unwound from the drum due to the drum overrunning the stopping of the platform at its lower terminus, and to maintain the whole of the cable unwound from the drum under tension.

Also, it is preferred to combine with the foregoing, means to effect an automatic re-laying of the cable under tensionupon the drum to wind in the portion of the cable which has been taken up as aforesaid.

'In addition, means is preferably provided to enable a reserve of cable length to be available for feeding into the effective length of cable when it is desired to increase the height of the hoist, and to take-in surplus cable when it is desired to shorten the height of the hoist, so that the effective length of the cable may be adjusted to within fine limits without having to disturb the connections of the cable ends to the appropriate parts of the hoist or to replace one cable with another cable.

By the expression transportable hoist, is contemplated either hoists in which a wheeled support is provided to facilitate its transport, or hoists so constructed that they may be erected on a desired site by assembling parts together, and can be disassembled into compact form for transport, and of course the present invention may be applied to hoists which are intended for use on a site for a quite protracted period so as not to require as a part of its construction a wheeled support.

In order that the invention may be clearly understood and readily carried into efiect, drawings tion and with the platform lifting and lowering cable unwound from the drum beyond the normal extent due to over-running of the drum beyond the platform stop ing position, and

Figure 4 is 'a detail sectional 'perspective view showing how the cable is attached to the drum,

so that, following complete unwinding of the cable from the winch drum, the surplus portion of the unwound cable can be rewound on to the drum. Referring to the drawings the tower or column l of the hoist is secured to a base frame 2 and has projecting rigidly from its rear uprights a frame 3- within which is secured a bed 1 carry ing the power unit driving the winch drum 6 for winding in the cable 1 to lift the platform 8 which is guided by rollers 9 carried by a frame Ill thereof along the angle section uprights of the tower or column I, this cable 1 being guided over sheaves or pulleys l I and the head of the tower i from the winch drum 6 to the platform frame ID, the cable not being actually secured to the platform frame In but being passed under a pulley l2 and returned to a suitable anchorage device over a channel section semi-circular guide bar [3 fixed to the head of the tower. The anchorage device proposed for use with the present invention is such as to take care of changes that might be effected in the height of the tower I, without having to unship the cable and replace it with another cable, whilst at the same time providing for fine degrees of adjustment of the effective length of the cabe in order that the means for taking care of slack tending to be produced in the cable when the winch drum 6 over-runs the platform 8 can be set in co-operation with the available length of cable to operate most effectively.

In the latter connection, instead of anchoring the appropriate end of the cable directly to a fixed point of the tower, a much greater length of cable than is required for the predetermined shorter height of column is provided, and the requisite anchorage of the cable to the tower is effected by taking several turns of the cable about three or other suitable number of grooved spools l4 secured to one of the rear uprights of the tower, the length of cable remaining after effecting this anchorage about the spools I4 being carried to an auxiliary drum l5 supported for rotation between side brackets I6 secured to upper triangular struts 3' of the engine and winch supporting frame 3. Any suitable means may be provided for rotating the drum [5 by hand.

The power unit 5 is connected to the winch drum 6 by a clutch and brake device controlled by a pull-rope l6 carried over an arm I! at the top of the column and secured to a lever H from which extends an extension [6 to the brake and clutch controlling member of the power unit. The front end of the lever H is engaged by the platform when it reaches its uppermost position so as to positively remove the operators tension on the rope IE to apply the brake between the power unit and the winch drum. In this connection, it is to be understood that when lowering the platform 8, the operator maintains a pull on the pull-rope IE to de-clutch the winch drum 6 from the power unit 5, slight relaxing of the tension on the pull-rope producing a proportional braking action to obviate too rapid a descent of the platform. For this purpose, the pull-rope I5 is connected to the combined clutch and brake device of the power unit and winch drum.

It will be appreciated from the foregoing, that an operator standing on the platform 8, or under some conditions standing on the ground or a part of the structure being fed by the hoist, should, immediately the platform reaches its lowermost position, release the tension on the pull-rope I6 so that the winch drum is braked and the working tension is retained in the cable 1 ready for a subsequent pulling up of the platform 8. However, it frequently happens that operators do not respond instinctively to release the tension on the pull-rope at the appropriate time, or unintentionally delay the release on the pull-rope, and as the winch drum is unwinding at the time, it will be evident that its inertia will produce an unwinding of the cable 1 remaining on the winch drum after the platform has reached its lowermost position, and in the past this has been found to be a cause of rapid wearing and deterioration of the cable, due to the irregular laying of the cable upon the drum and/or to the cable becoming caught over parts of the hoist or coming adrift from the pulleys I I and/or l2.

In the embodiment of the invention illustrated, the production of slack in the cable due to the over-running of the winch drum is prevented by spring means actuating a member carrying a subplementary guide for the cable so that this guide is displaced to take up the slack in the cable which otherwise is produced by the winch drum 6 over-running the platform 8 when the platform reaches its lowest position. This spring means is normally inoperative, but is loaded immediately the platform reaches its lowest position, so that as the winch drum over-runs the platform and consequently feeds out more cable than is required, the spring means which is energized as the cable reaches its lowermost position causes displacement of the said supplementary guide. This supplementary guide comprises a short length of circular section rod l8 projecting uni-laterally from the upper end of a lever arm Hi, this lever l9 being of the first order, the driving force being applied to the shorter limb of the lever, the fulcrum 20 being constituted by a pin in a forked bracket 2|, the spring means comprising a tension spring 22 connected by a cable 23 to the lower end of the lever 19 and to the free end of an arm 24 pivoted at its upper end to a forked bracket 25 on the base frame 2, and maintained raised by reason of the prepondering weight of the upper limb of the lever l9 causing its upper end to lean against the rear part of the tower l with its supplementary guide I8 free of the cable 1.

The platform 8 has a rearwardly projecting abutment 26, which, as the platform nearly reaches its lowermost position engages the free end of the lever and preloads the spring 22 against the tension in the cable 1, with the result that in the event of the operator not releasing the pull on the pull-rope I6 immediately the platform 8 reaches the frame 2, the preloaded spring 22 will cause the arm l9 to swing rearwardly in the position shown in Figure 3 to take up the surplus length of cable unwound from the winch drum 6 due to the winch drum under its own inertia over-running the platform 8.

In practice, the length of cable available upon the winch drum 6 immediately the platform 8 reaches its lowermost position need only comprise two or three turns, and these turns are taken up by the lever l 9 being urged away from its normal position by complete reassertion of the spring 22. If the winch drum 6 continues to rotate beyond the position in which the whole of the cable is fed therefrom, it will rewind the surplus length of the cable back upon itself in the reverse direction to the normal winding-in direction, or at least it will re-wind a part of the length of the surplus length of cable, in which event the spring loaded arm l9 will take care of the remainder of the surplus of the cable.

To ensure the cable wrapping in the proper manner about the barrel of the drum, for either direction of wrapping, the cable end connected to the drum is threaded through a hollow stud 21 (see Figure 4) freely rotatable in an end flange 6 of the drum. By this means the very short length of cable end which radiates from the hollow stud to the periphery of the barrel :of the drum will readily change its direction about the axis of the hollow stud to ensure the cable laying properly in either direction about the barrel of the drum.

Transverse rods 28 are secured to the tower @l by spacer members ZQ above and belowthe'transverse abutment I8 to assist in guidin'g'th'e cable 1 and also to maintain the parts of the cable leaving the pulleys 1 2 and running clos to the winch drum in parallel relationship with the tower I.

:Iclaim:

l. A hoist of the type in which :aplat'form adapted to be drawn up and lowered down a tower is connected by a cable'to a winch drum via guiding means at the top o'ftheho'ist tower and in which the winch drum is driven by a power unit controlled for the raisin and lowering of the platform by manually operated .remote control -means, -character ised that means is provided adapted in the event of the remote control means not being controlledso a to arrest unwinding :of the winch edrum immediatel-y'the platform reaches its lower terminus, to take up the surplus length of cableasitis unwound from the drum due 'to the drum over-running the "with a'flexible extension by which the spring :is

connected at one end to one .of said members, the other end of the spring being :operatively "connected to the other said member.

'7. hoist according to claim 6 wherein said disp'laceable member is an arm pivoted a't one end to the base of the hoist, the said :coiled spring bein connected to its other end, the platform "having an abutment adapted as the platstopping of the platform "at its lower terminus,

and to maintain the who'lem'f the=cab1e unwound from the drum under tension.

2. A hoist of the type in which a platform adapted to be drawn up and lowered down a tower is connected by a cable to a winch drum via guiding means at the top of the hoist tower and in which the winch drum is driven by a power unit controlled for the raising and lowerin of the platform by manually operated remote control means, characterised by an auxiliary guide for the cable between the platform and the winch drum on to which the cable is wound when the platform is being raised, spring means being provided adapted to displace the auxiliary guide to take up the surplus cable fed from the drum due to drum over-running the platform when the platform reaches its lowest position.

3. A hoist according to claim 2 wherein said spring means is inoperative upon the auxiliary guide for the cable when the platform is travellin but is loaded 01 energised automatically as the platform completes its descent whereby in the event of the drum over-running the fully lowered platform the spring means reasserts itself to cause displacement of the said auxiliary guide to take up said surplus cable.

4. A hoist according to claim 3 wherein said auxiliary guide is carried by a lever member and is located between the cable and the hoist tower, said auxiliary guide being positioned on the lever member so as to have a greater movement of translation than the part of the lever member to which the effort of said sprin means is applied, the lever member occupyin by gravity the position in which the auxiliary guide is inoperative upon the cable.

5. A hoist according to claim 4 wherein said spring means is connected across said lever member and a member displaceable by the downward pressure of the platform as the platform completes its descent whereby the spring means is loaded by the final movement of the descending platform by reason of the cable serving as an abutment opposin displacement of the lever.

6. A hoist according to claim 5 wherein said form completes its descent to strike and depress the arm against the influence of the spring, :the other end of the spring being connected to a cable bent over .a guide and connected at its other end to the lever member.

8. In combination a hoist tower with :a:p1a'tform adapted to be drawn upand lowered :dOWIl the tower, manually remotely controlled power driven cable winding means to elevate the platform along the tower and to which means and the :platform aicable is connected, uiding means .at the top of the .hoist tower by whichrthe cable is guided up from the platform and :downzto the -power.:driven winding .rneans,.tmean adapted in the event of the remote control :means .not abeing controlled so as 'to arrest unwinding of the winding .nieans immediately 1. the, platform reaches its lower terminus, to take u the surplus length of cable as it is unwound from the winding means due to the winding means overrunning the stopping of the platform at its lower terminus, and to maintain the whole of the cable unwound from the winding means under tension, and means to effect an automatic re-winding in of the cable under tension on to the winding means to recover the surplus cable fed off the winding means due to the winding means overrunning the lowered platform.

9. In combination a hoist tower with a platform adapted to be drawn up and lowered down the tower, manually remotely controlled power driven cable winding means to elevate the platform along the tower and to which means and the platform a cable is connected, guiding means at the top of the hoist tower by which the cable is guided up from the platform and down to the power driven winding means, an auxiliary guide for and acting upon the length of cable lying between said guiding means and the winding means, and spring means in co-operative association with but inoperative upon the auxiliary guide for the cable when the platform is travelling but which is loaded or energised automatically as the platform completes its descent whereby in the event of the winding means overrunning the fully lowered platform the spring means asserts itself to cause displacement of the said auxiliary guide to take up the surplus length of cable as it is unwound from the winding means due to the winding means over-running the stopping of the platform at its lower terminus.

10. In combination a hoist tower with a platform adapted to be drawn up and lowered down the tower, manually remotely controlled'power driven cable winding means to elevate the platform along the tower end and to which means and the platform a cable is connected, guiding means at the top of the hoist tower by which the cable is guided up from the platform and down to the power driven winding means, an auxiliary guide for and acting upon the length of cable lying between said guiding means and the Wind- 'ing means, and spring means in co-operative association with but inoperative upon the auxiliary guide for the cable when the platform is travelling but which is loaded or energised automatically as the platform completes its descent whereby in the event of the winding means over-running the fully lowered platform the spring means asserts itself to cause displacement of the said auxiliary guide to take up the surplus length of cable as it is unwound from the winding means due to the winding means over-running the stop-' ping of the platform at its lower terminus, the- 'cable being wound upon the winding means to a length in excess of the requirements for completely raising the platform corresponding to the full amount which can be taken up when the winding means over-runs the platform, the cable' being so connected to the winding means that in the event of the winding means over-running the stage at which all of the cable is removed therefrom the winding means will relay back on to power driven winding means, means adapted in the event of the remote control means not being controlled so as to arrest unwinding of the winding means immediately the platform reaches its lower terminus, to take up the surplus length of cable as it i unwound from the winding means due to the winding means over-running the stopping of the platform at its lower terminus, and to maintain the whole of the cable unwound from the winding means under tension, and means provided to enable a reserves of cable length to be available for feeding into the effective length of cable when it is desired to increase the height of the hoist. and to take-in surplus cable when it is desired to shorten the height of the hoist, so that the effective length of the cable may be adjusted to within fine limits without aving to form joints therein or to disturb the connections of the cable ends to the appropriate parts of the hoist or to replace one cable with another cable.

REGINALD FRANK WARRY.

REFERENCES CITED FOREIGN PATENTS Country Date Great Britain May 28, 1948 Number

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