GB2061861A - Rope guides for hoists - Google Patents

Abstract

In a winch or hoist having a helically grooved barrel 10 and a guide 22, traversable axially of the barrel to guide the rope 18 into the groove, chafing by and wear of the guide and/or groove edges by the rope is substantially eliminated by providing a guide (22) having a through passage (47) having an entry portion flared outwardly about a line substantially tangential to the barrel 10. The passage may be of circular cross-section and diverge from being substantially parallel to the tangential line at a position adjacent the barrel to being substantially perpendicular thereto at the entry position. Traversing of the guide in synchronism with barrel rotation may be provided by one or more protrusions engaging the empty helical groove. <IMAGE>

Description

SPECIFICATION Rope guides for hoists The invention relates to winches and hoists, and is particularly applicable to hoists having a helically grooved barrel and a guide, traversable axially of the barrel, to guide the lifting rope into the helical groove.

In using such hoists any vertical misalignment of the load and the point at which the rope engages the drum (usually vertically tangential) will result in lateral movement or "dragging" of the load, and hence the rope, during lifting.

It has been found that such "dragging" often causes chafing of the guide by the rope as it passes through the guide, especially where the rope passes through a slot, in the guide, little wider than the diameter of the rope. Then localised application of the lateral forces may result in widening of the slot to the extent that accurate guidance is jeopardised or even result in breakage of the guide.

Increasing the width of the slot to avoid chafing by the rope reduces the accuracy of alignment of the rope with the helical groove, thus increasing the likelihood of chafing of the edges of the groove.

An object of the present invention is to eliminate or at least mitigate these problems and to this end there is provided a winch or hoist having a helically grooved barrel and a guide traversable axially of the barrel during rotation thereof to guide the rope into the groove, the guide comprising a through passage having an entry portion flared outwardly about a line substantially tangential to the barrel.

Preferably the interior walls of the entry portion converge, at least in a plane parallel to the axis of the barrel, to a dimension only slightly larger than that of the rope, facilitating accurate alignment of the rope with the helical groove during lifting or "laying-on" Conveniently the entry is of circular crosssection and its walls curve from being substantially parallel to the tangent at a position adjacent the barrel, to being substantially perpendicular thereto at its entry position.

Advantageously at least the entry portion of the guide comprises two parts which can be separated for removal of the guide from around the rope without axial unthreading.

In preferred embodiments the guide is supported by, and slidable axially along, an outer casing of the hoist, and carries a grooveengaging member to provide synchronous traversing movement of the guide relative to the barrel during its rotation. A pressure ring may be provided to bias one or more turns of the rope into the underlying groove to prevent them unwinding or lifting when the load is removed.

Whilst the required traversing movement may be obtained by engaging the groove at one point only, it is preferable to engage the barrel over a greater axial extent, say for several turns of the groove. Such an arrangement provides additional support for the guide against lateral forces applied to the flared mouth portion by sideways movement of the load and which tend to lift the groove engaging member and/or pressure ring away from the barrel.

An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings, in which Figure 1 is a sectional partial view of the rope barrel of a hoist with a rope guide according to the invention; Figure 2 is a partial side elevation showing the rope guide; Figure 3 shows the sectional profile of onehalf of the guide mouth taken on line AA of Fig. 1, Figure 4 is a view corresponding to Fig. 3 but taken on line BB of Fig. 1 and Figure 5 is a partial sectional view on the line of Fig. 2.

Referring to Figs. 1, 2 and 3, a hoist comprises a steel barrel 10 rotatable about its axis 1 2 in a cylindrical outer casing 14 by an electric motor (not shown). For substantially the whole of its length the barrel 10 has a circumferential helical groove 1 6 of semi-circular profile to receive a twisted wire rope 18, which is anchored at one end of the barrel, passes around the pulley of a lifting hook (not shown) and is anchored at its other end relative to the hoist outer casing 1 4. Rotation of the barrel 10 in the clockwise direction indicated in Fig. 1 by arrow A, winds the rope 1 8 onto the barrel to lift the hook.

The casing 14 has an opening 20 extending axially throughout a major part of its length and, circumferentially, from a point slightly above the axis of rotation of the barrel through an arc of about 90 .

A rope guide 22 comprises an arcuate member 24 of phosphor bronze, cast iron or other suitable material extending around part of the circumference of the barrel 10 across the opening 20 and slidably engaging behind the casing 1 4 at each edge of the opening 20. Medially of its axial width the member 24 has a slot 26 through which the rope 18 passes to the barrel 1 0. Two curved casing parts 28 and 30, attached edge-to-edge and to the arcuate member 24 by screws 32 and plate 34, are of similar radius to the casing 14 and fit slidingly into the opening 20. The combined width of the two portions is equal, approximately, to six turns of the helical groove.Flanges 40 and 42, extend from abutting edges of the curved portions 28 and 30, respectively, in a plane generally perpendicular to the axis of the barrel and are secured together by bolts 44, 45 and 46 extending through registering holes in the two flanges.

Each of the flanges 40 and 42 is flared outwardly and downwardly from its junction with the corresponding curved portion 28 or 30 to form, between them, a passage 47 communicating with the slot 26. The entry portion of the passage has a bell-mouth 48 which is of circular cross-section and coaxial with the vertical portion of the rope passing through the slot 26 i.e. substantially vertically tangential to the barrel 1 0. At its narrowest part 50, immediately adjacent the slot 26, the mouth 48 has a diameter only slightly larger than that of the rope.

Referring to Fig. 5 it will be seen that part 52 of the arcuate member 24 disposed to one side of the slot 26 has three helical protrusions 54, each conforming in cross-section to the groove. As seen from Fig. 5 the arrangement is such that, when the protrusions 54 engage the grooved surface of the barrel, the slot 26 and the narrowest part 50 of the bellmouth entry to the guide are in vertical alignment with the turn of the groove into which the rope is being laid or vice versa.

Rotation of the barrel causes screw-wire traversing of the protrusions 54, and hence the guide member along the barrel 10, thus maintaining the required alignment. The outer surface of the part 52 is stepped, the part 53 adjacent the slot 26 being of lesser radius than the remainder, to receive a clamping band (not shown) to clamp the member 24 against the barrel. Preferably a plurality of similar groove-engaging segments 24 are clamped in a continuous ring around the barrel. However, the requirement for a clamping band could be removed by providing a continuous groove-engaging ring screwed onto the barrel to the desired position during assembly.

At the opposite side of the slot 26, the arcuate member 24 has a rectangular groove 56 directed towards the surface of the barrel 10. A pressure ring 58, of spring steel and channel section is located with one upturned flange 60 in the groove 56 and extends around the barrel with its web portion 62 bearing against the underlying three coils 64 of the rope. Thus, when the tension is removed from the rope, for example when the load is removed, the rope is prevented from uncoiling from the groove. The pressure ring may also comprise a plurality of segments allowing it to be threaded into its position around the barrel.

It should be noted from Fig. 1 that the interior surface of the passage 47 curves from being substantially vertical adjacent the narowest, upper portion, to being substantially horizontal at the lowermost edge 66 of the guide.

Thus, significant vertical misalignment of hoist and load, resulting in the rope entering the mouth non-vertically, can be tolerated without significant chafing or wear of the guide, particularly since the curvature of the mouth portion distributes the lateral forces.

Moreover, the smallest diameter of the passage i.e. adjacent the slot 26, can be much smaller than that practicable for the usual slotted guide without chafing, facilitating more accurate "laying-on" of the rope. Also, the thickness of the material at the mouth of the guide may be much greater than a conventional slotted guide, this permitting greater wear without failure.

In the specific embodiment the groove-engaging protrusions 54 have been described as spanning three turns of the groove. This has been found advantageous in view of the increased lateral forces applied to the guide member and which, in known hoists, would tend to unseat the projections from the groovy and, lift the pressure ring, even to the extent that layering (i.e. the rope winding upon itself) couid take place leading to severe damage.

However, it wll be appreciated that a single point of engagement is all that is necessary to provide traversing movement.

It should also be noted that embodiments of the invention having two casing parts forming the guide advantageously can be assembled around the rope without threading.

Hence it is not necessary to disconnect an end of the rope to fit or remove the guide.

Whilst especially applicable to hoists, the invention comprehends winches having a helically grooved barrel and axially traversable guide.

Claims (11)

1. A winch or hoist comprising a rotatable barrel having a circumferential helical groove to receive a lifting rope and a guide traversable axially of the barrel to guide the rope into the groove, wherein the guide has a through passage having an entry portion the interior surface of which is flared outwardly about a line substantially tangential to the barrel.

2. A winch or hoist as claimed in claim 1, wherein the interior of the passage diverges from a dimension, at least in a plane parallel to the barrel axis, substantially equal to, but greater than, that of the rope.

3. A winch or hoist as claimed in claim 1 or 2, wherein the interior walls of the passage curve from being substantially parallel to the tangent at a point adjacent the barrel, to being substantially perpendicular thereto at the entry to the passage.

4. A winch or hoist as claimed in claim 3, wherein the passage is of circular cross-section at least at its narrowest part.

5. A winch or hoist as claimed in claim 1, 2, 3 or 4, wherein the guide comprises two parts which are separable to permit their re moval radially from around the rope.

6. A winch or hoist as claimed in any preceding claim, wherein the guide is slidably supported in an opening in an outer casing of the hoist, the opening extending axially for a major part of the length of the barrel.

7. A winch or hoist as claimed in claim 6, wherein the guide comprises an arcuate member slidably engaging within the edge portions of the opening and having a slot extending in the circumferential direction and through which the rope passes to the barrel, the interior of the said through passage communicating with the slot.

8. A winch or hoist as claimed in claim 7, wherein the arcuate member has at least one protrusion projecting radially inwardly from a position to one side, axially, of the slot for engaging an empty turn of the helical groove so as to cause axial movement of the guide in response to rotation of the barrel.

9. A winch or hoist as claimed in claim 8, wherein the arcuate member has a plurality of protrusions each engaging a different turn of the groove.

10. A winch or hoist as claimed in claim 7, 8 or 9, wherein the arcuate member is one of a plurality of arcuate members disposed end-to-end around the circumference of the barrel.

11. A winch or hoist as claimed in any one of claims 7 to 10, wherein the or each arcuate member is clamped to the barrel surface by a circumferential clamping band or ring.

1 2. A winch or hoist as claimed in any of claims 7 to 11, wherein the first-mentioned arcuate member has means disposed at the other side, axially, of the slot for biassing one or more turns of the rope into the underlying groove.

1 3. A winch or hoist as claimed in claim 12, wherein the means for biassing the turn or turns of rope comprises a pressure ring having a surface directed towards the barrel, and located in position by engagement with a recess or slot in the radially inwardly directly surface of the arcuate member.

1 4. A winch or hoist substantially as herein described with reference to, and as shown in, the accompanying drawings.