This invention relates to a winch assembly which includes a winch comprising a roller and means for restricting rotation of the roller at least in one rotational direction.

A portable winch is disclosed in US-5168958 which comprises a roller mounted on a backplate for rotation, and components which prevent rotation of the roller in one direction. A working line such as a rope is wrapped around the roller two or three times and can be pulled in one direction with the roller as it rotates. Movement of the line in the opposite direction is restricted by the restricted movement of the roller and by friction between the line and the roller.

The disclosed winch suffers from a number of disadvantages. In particular, there can be a tendency for one turn of the working line on the roller to override another turn, in particular when tension on the line is reduced.

The present invention provides a winch which includes a housing which is closed at its top and bottom, the clearance between the roller and the housing being such that one turn of the working line cannot override another turn.

Accordingly, in one aspect, the invention provides a winch which comprises a housing, a roller mounted in the housing for rotation, means for restricting rotation of the roller at le ^* =st in one rotational direction, and a working line that is wrapped around the roller at least twice, the housing being open at its sides to enable the working line to pass onto the circumferential surface of the roller and closed at its top and bottom, the space between the circumferential surface of the roller and the adjacent internal surface of the housing at its top and bottom being small enough to prevent one turn of the working line overriding another turn.

The winch of the present invention has the advantage that the two or more turns of a working line around the roller are retained securely on the roller and cannot be displaced from it, other than by unthreading the line. This makes the assembly capable of being handled in such a way that might otherwise give rise to the working line becoming displaced from the roller, or to one turn of the line overriding another turn or to other entangling of the line. This can ensure more reliable performance of the winch when in use, for example even when the tension in the working line is reduced. It also enables the winch to be transported before use and then be ready for use with the working line properly installed on the roller.

The housing can have formations on its top and bottom for attachment. For example, a formation can be used to mount the winch, for example by attaching it to a hook. A formation can be used to attach a load to the winch. The formations can take the form of, for example, hooks or eyes.

A further advantage of the winch assembly of the invention is that load can be attached to the winch, and the winch can be mounted, symmetrically with respect to the support for the roller in the housing. The roller can be supported by means of an axle extending between opposite sides of the housing which facilitates proper bearing support for the roller across its entire width. The closed top and bottom of the housing then enable a load to be applied to the housing centrally with respect to the roller. Moreover, the resulting winch is compact.

Preferably, the internal configuration of the housing is substantially box-shaped when viewed from one side generally perpendicular to the axis of rotation of the roller. Generally, the external configuration of the housing will also be substantially box-shaped. The housing can be formed from an extrusion with a hollow cross-section, for example by mounting

the roller in a length of the extrusion. The housing might be formed by a process which includes one or more of machining, or manipulating a sheet for example by bending and then joining the free ends of the sheet .

The means for restricting rotation of the roller can comprise a ratchet. Preferably, the rotation is restricted by means of a sprag clutch. This can have the advantage of providing more accurate and precise control of the rotation of the roller.

Preferably, the roller is mounted for rotation on bearings. It can be preferred for many applications for a sprag clutch included to restrict rotation of the roller to ^* be combined with one of the bearings, reducing one or more of the cost, size and weight of the winch.

Preferably, components associated with rotation of the roller, such as bearings or components associated with restricting the rotation of the roller, are sealed against ingress of contaminants such as moisture, dust and so on.

Preferably, the winch assembly includes a multi-purchase block and tackle, more preferably attached to the winch, for example to a formation on the bottom of the winch.

The working line used in the winch assembly will generally comprise a rope formed from a textile material, especially with a core and a woven or braided outer sheath. However, other lines can be used, including metal rope, chains, string and so on.

The working line and the roller are preferably arranged so that the roller can accommodate at least two complete turns of the line around the roller and a part turn, amounting to about 2 turns. For some applications, however, more than two turns can be appropriate, for example 3 turns or more.

The winch assembly of the invention can be used to lower and raise a load, especially a person. The retention of the working line on the roller by the housing means that the winch can be transported to a location in which it is to be used with the working line in place on the roller with the winch then ready for use. When the assembly includes a multi-purchase block and tackle, for example with one part of the block and tackle attached to the winch (especially to a formation on the bottom of the housing) , the load to be lifted can be attached to the other part of the block and tackle. The load can be lifted by pulling the working line around the roller in the direction in which the roller can rotate. Lowering of the load can be controlled relying on frictional effects between the roller and the line. When the load that is to be raised and lowered is a person, he can himself pull the line around the roller and let it out so that he controls the raising and lowering himself.

The winch assembly of the invention finds particular invention in which a person has to be raised or lowered and in which other lifting arrangements (such as a ladder) is not available or cannot be used. Examples include descending into a pipe, scaling or descending a sheer and so on.

The winch assembly of the invention can include a support for the winch on which the winch can be attached, for example in the form of a hook or eye or such like, for a load then to be attached thereto. The support might be, for example, a hook mounted on a rack or ladder, or fastened to a surface such as a wall, rock face, pipe wall or such like.

The diameter of the circumferential surface of the roller is preferably at least about 6 cm, more preferably at least about 8 cm, for example at least about 10 cm. The width of the roller will be selected according to the size of the working line to be used on the winch and the number of turns thereof. The internal dimension of the housing will be selected so that

the distance between the internal surface of the housing and the external surface of the roller is at least slightly greater than the thickness of the working line, for example at least about 1.2 times its thickness. The distance will be less than twice the thickness of the working line, for example less than about 1.7 times its thickness, more preferably less than about 1.5 times.

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic view of a winch assembly according to the invention, and

Figure 2 is a sectional elevation through the winch of the assembly shown in Figure 1.

Referring to the drawings, Figure 1 shows a winch assembly which comprises a winch 2 and a block and tackle 4 attached to the bottom of the winch. A rope 6 passes around the block and tackle and the winch.

Figure 2 shows the winch 2 in greater detail. it comprises a housing 8 formed from steel, having a generally rectangular box-shaped cross-section. The housing has eyes 10, 12 formed integrally on its top and bottom surfaces by which the winch can be attached to a support, or to which a load can be attached to the winch.

A roller 14 is mounted in the housing on an axle 16 which extends between opposite side faces of the housing. The roller is mounted on bearings 18. A sprag clutch restricts rotational movement of the roller in one direction. In the described embodiment, the sprag clutch 19 is combined with one of the bearings .

The roller has a circumferential bearing surface 20 defined laterally by two walls. A working line in the form of the rope 6 with a woven outer casing is wrapped around the roller between the said walls about 2% times.

The winch includes seals 22, in the form of oil seals in the described embodiment, to prevent ingress of contaminants into the bearings and the sprag clutch.