GB2210846A - Manually operated hoist - Google Patents

Abstract

A manually-operable hoist has a non-traversing rope drum (67) with a directly-connected driving shaft for fast winding and a second driving shaft (73) connected to the drum through a friction clutch or clamp arrangement and a gear reduction transmission for slow winding. The clutch comprises a pair of friction surfaces which sandwich a ratchet wheel 87 whose central portion (88) is conical. The ratchet wheel is clamped by movement of a cam nut (89) which bears against an abutment face (83), Fig 6 (not shown). The gear reduction transmission includes a chain wheel (78) connected by a chain (96) to a larger chain wheel (97) located on a shaft (98) with small chain wheels (100) which drive respective larger chain wheels (102). <IMAGE>

Description

HOISTS This invention relates to hoists, and in particular manually-operable hoists such as are manufactured and sold by us under our Registered Trade Mark MINILIFT.

Such a hoist comprises a governor controlled winding mechanism and a traversing rope drum and as a result is of relatively heavy weight which sometimes causes an operator difficulty in use and it is an object of the present invention to provide such a hoist of relative-ly light weight.

The term 'I rope" used herein and in the claims is to be construed to include any flexible elongate element used in hoists between a winding drum and a hook, cradle or similar engageable with the article to be hoisted.

According to the present invention therefore there is provided a manually-operable hoist comprising a non-traversing rope drum rotatable through the intermediary of a friction clutch (or clamp) gear reduction transmission.

As a result of the present invention the usual governor controlled winding gear is omitted as is the traversing mechanism for the rope drum whereby the hoist weight is substantially reduced.

Preferably the gear reduction transmission is a roller chain and wheel arrangement.

Preferably the input shaft to the gear reduction transmission has fitted thereto a driving dog which operates a screw-clamping or clutching assembly when rotated by a handle to effect a winding-up operation.

On unwinding the clamping or clutching assembly is released.

A second driving dog is preferably provided and is connected directly to the rope drum.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a side elevation of a hoist according to the present invention; Fig. 2 is a sectional view of the hoist on the line II-II of Fig. 1 and to an enlarged scale; Fig. 3 is a part-sectional view on the line Ill-Ill of Fig. 2; Fig. 4 is a sectional view on the line IV-IV of Fig. 5 of an alternative and preferred hoist construction according to the invention; Fig. 5 is a side view of the hoist of Fig. 4 open to illustrate the interior; Fig. 6 is a side sectional view of the friction clamp or clutch drive of the hoist of Figs. 4 and 5; Fig. 7 is an end view of a part of the friction drive of Fig. 6; and Fig. 8 is a side view and a detail view of a rope guide tube and a top sheath associated therewith.

Referring to Fig. 1 in particular, the hoist comprises a winding mechanism assembly generally indicated at 10 with a removable handle 11 and mounted on a wheel or roller assembly 12 for movement. The winding mechanism assembly 10 has removably fitted thereto a rope guide tube 13 on the remote end of which is a sheave 14 having secured thereto a suspension hook 15, the rope 16 of the hoist passing, as is usual around the sheave 14 and terminating in a hook 17 for engaging the article (not shown) to be hoisted. Guide tubes 13 of different lengths to suit requirements can be fitted to the winding mechanism assembly 10.

The winding mechanism assembly 10 comprises a multi-part casing 18 for housing the winding gear.

The casing 18 can be disassembled for internal access purposes and has a tangential socket 19 for rope egress and connection of the guide tube 13.

Alternatively a guide tube 13 of telescopic construction is provided.

The winding gear comprises a circumferentiallygrooved, non-traversing, rope drum 20 rotatably mounted in bearings 21, there being a driving dog 22 directly connected to a driving spindle 23 integral with the rope drum 20 and to which the winding handle 11 can be fitted. This provides a "fast" winding facility for the hoist. The rope drum 20 has a rope securement device 24 for anchoring one end of the rope 16 and a rope guide 25 is provided at the socket 19.

The winding gear also includes a "slow" winding facility for the hoist.

This comprises a driving spindle 26 and integral chainwheel 27 supported in bearings 28 and having connected thereto a driving dog 29 secured by a screw 30. The driving spindle 26 also carries a friction disc arrangement 31 which clamps and drives a ratchet wheel 32 which, in turn, engages pawls 33 for back stop braking. The chain wheel 27 is connected by a roller chain 34 to a relatively large diameter chain wheel 35 supported on a rotatable shaft 36 supported in bearings 37. This shaft 36 is formed at one end as a relatively small diameter chain wheel 38 connected by a multiple roller chain 39 to a relatively large diameter chain wheel 40 fitted to the rope drum 20.

The chain wheels 27, 35, 38 and 40 and the roller chains 34 and 39 thus constitute a gear reduction transmission between the driving dog 29 and the rope drum 20.

A fully wound-out stop for the rope 16 is indicated at 41.

In use, clockwise or forward rotation of the driving dog 29 by the handle 11 tightens the friction disc arrangement 31 and effects rotation of the rope drum 20 to raise the load and secure the back stop ratchet wheel 32 via the pawls 33. Anti-clockwise or reverse rotation slackens the friction disc arrangement 31 to release the ratchet wheel 32 thus allowing slippage of the load for lowering.

Cessation of winding immediately allows the load to tighten the friction disc arrangement.

Referring now to the preferred embodiment of Figs. 4 to 8, the hoist comprises a winding mechanism assembly generally indicated at 50 with a carrying handle 51 and mounted on a wheel or roller assembly 52 for movement. The winding mechanism assembly 50 has removably fitted thereto a rope guide tube 53 (see Figs. 4 and 8) on the remote end of which is mounted a top sheath assembly 54 which sockets onto an extension tube 55 of the guide tube 53 welded to the latter. The top sheath assembly 54 comprises a casing 56 having a split collar formation 57 which engages around the tube extension 55 and is secured in position therearound by a locking bolt 58.

The casing 56 houses a rotatable pulley 59 around which a rope 60 of the winding mechanism assembly 50 can pass, there being a load-engaging hook 61 on the end of the rope 60.

The top sheath assembly 54 is provided with a suspension hook 62 and alternative suspension means in the form of lateral trunnions 63.

The guide tube extension 55 is provided with an internal flared bore 64 to assist guidance of the rope 60 from the guide tube 53 to the pulley 59.

Guide tubes 53 of different lengths or of telescopic construction to suit requirements can be fitted to the 'winding mechanism assembly 50.

The winding mechanism assembly 50 comprises a multi-part casing 65 for housing the winding gear, the casing 65 can be disassembled for internal access purposes and has a tangential socket 66 for rope egress and connection of the guide tube 53.

The winding gear comprises a circumferentiallygrooved, non-traversing, rope drum 67 rotatably mounted in bearings 68, there being a driving dog 69 directly connected to a driving spindle 70 integral with the rope drum 67 and to which a winding handle 71 can be fitted. This provides a "fast" winding facility for the hoist. The rope drum 67 has a rope securement device (not shown) identical with the device 24 of Fig. 3 provided at location 72 for anchoring one end of the rope 60. A rope guide (not shown) identical with the rope guide 25 of Fig. 3 is provided at the socket 66.

The winding gear also includes "slow" winding facility for the hoist.

This comprises a driving spindle 73 to which is secured by a screw 74 a driving dog 75 for receiving the winding handle 71 and rotatably supported in a bearing 76. It also comprises a driven spindle 77 having an integral chainwheel 78 and being rotatably supported in a bearing 79.

The driving spindle 73 and driven spindle 77 are adapted to be drivingly coupled together by a friction drive (see Figs. 4,6 and 7).

The friction drive comprises a yoke 80 integral with the driving spindle 73, the yoke 80 having at its inner end a cylindrical body 81 with a conical face 82 and internally an inclined abutment face 83.

The driving spindle 77 has a square section 84 engaged within a square-bored sleeve 85 of an inner driven cone 86, there being between the conical face 82 and the latter a ratchet wheel 87 having a central conical body 88 with a cylindrical bore which surrounds the sleeve 85.

The sleeve 85 within the yoke 80 is screwthreaded and a cam nut 89 is screwed thereon as indicated at 90 and is locked in position against rotation relative to the sleeve 85 by a locking screw 91.

The cam nut 89 bears against the inclined abutment face 83.

Brass cones 92, 93 are respectively provided between the conical face 82 and the ratchet conical body 88 and the latter and the driven cone 86.

The ratchet wheel 87 has associated pawls 94 which engage with the ratchet wheel 87 for back stop braking purposes. Springs 95 urge the pawls 94 into engagement with the ratchet wheel 87.

The chain wheel 78 is connected by a roller chain 96 to a relatively large diameter chain wheel 97 supported on a rotatable shaft 98 supported in bearings 99. This shaft 98 has integral therewith relatively small diameter chain wheels 100 connected by a multiple roller chain 101 to a relatively large diameter chain wheel 102 connected with the rope drum 67.

The chain wheels 78, 97, 100 and 102 and the roller chains 96 and 101 thus constitute a gear reduction transmission between the driving dog 75 and the rope drum 67.

A fully wound-out stop (not shown) for the rope 60 is provided and is identical with that shown at 41 in Fig. 3.

In use, clockwise or forward rotation of the driving dog 75 by the handle 71 causes the yoke 80 through its internal inclined abutment face 83 to ride up the cam nut 89 to press the conical face 83 of the yoke 80 into frictional locking engagement with the driven cone 86 through the intermediary of the conical body 88 of the ratchet wheel 87 and the brass cones 92, 93 and so effect rotation of the rope drum 66 to raise the load and secure the back stop ratchet wheel 87 via the pawls 94. Anti-clockwise or reverse rotation slackens the friction drive arrangement to release the ratchet wheel 97 thus allowing slippage of the load for lowering.

Cessation of winding immediately allows the load to tighten the friction drive.

The preferred arrangement described with reference to Figs. 4 to 8 has improved heat dissipation qualities compared with the arrangement illustrated and described with reference to Figs. 1 to 3 due to the construction of the friction drive.

Claims (14)

1. A manually-operable hoist comprising a non-traversing rope drum rotatable through the intermediary of a friction clutch (or clamp) driven gear reduction transmission.

2. A hoist as claimed in claim 1 in which an input shaft to the gear reduction transmission has fitted thereto a driving dog which operates a screw-clamping or clutching assembly when rotated by a handle to effect a winding-up operation.

3. A hoist as claimed in claim 2 in which the clamping or clutching assembly comprises a friction disc arrangement adapted to clamp and drive a ratchet wheel with which is associated pawls, the ratchet and pawls acting as a back stop brake.

4. A hoist as claimed in claim 1 in which the friction clamp or clutch comprises a yoke secured to an input shaft of the gear reduction transmission, the yoke having a conical friction face cooperating with a driven cone of the gear reduction transmission through the intermediary of a ratchet, the yoke being adapted to cooperate with a cam surface, upon winding rotation of the input shaft, to clamp the conical friction face and the driven cone together for simultaneous rotation.

5. A hoist as claimed in claim 4, in which the driven cone has a sleeve passing through a bore in a conical body of the ratchet wheel into the yoke, the sleeve, within the yoke mounting a cam adapted to cooperate with an abutment face of the yoke to effect the clamping action upon winding rotation.

6. A hoist as claimed in claim 5, in which the sleeve and cam are screw-engaged and locked against relative rotation.

7. A hoist as claimed in any one of claim 4 to 6 in which the ratchet wheel has associated pawls, the cooperating ratchet wheel and pawls serving as a back stop brake.

8. A hoist as claimed in any one of claims 1 to 7 in which the gear reduction transmission is a roller chain and pulleys arrangement.

9. A hoist as claimed in any one of claim 1 to 8 in which a driving shaft is directly connected to the rope drum.

10. A hoist as claimed in claim 9 comprising a driving dog connected to the direct driving shaft and adapted to receive the handle for fast rotation of the rope drum.

11. A hoist as claimed in any one of claims 1 to 10, comprising a rope guide tube in communication with the rope drum, there being at the hoist-remote end a pulley over which a rope from the rope drum is wound.

12. A hoist as claimed in 11 in which the pulley is rotatably enclosed within a sheath.

13. A hoist as claimed in claim 12, in which the sheath has a suspension hook and suspension trunnians.

14. A manually operable hoist, substantially as hereinbefore described with reference to Figs. 1 to 3 or Figs. 4 to 8 of the accompanying drawings.