WO2001033109A1

WO2001033109A1 - Improved pulley

Info

Publication number: WO2001033109A1
Application number: PCT/AU2000/001317
Authority: WO
Inventors: Boris Rogelja
Original assignee: Boris Rogelja
Priority date: 1999-10-29
Filing date: 2000-10-27
Publication date: 2001-05-10
Also published as: AU1117101A; AUPQ377299A0

Abstract

Pulley (10) includes a drum with axle (26) mounted between two plates (18, 20) for receiving a rope (14). A rotatable friction roller is spaced from and oriented parallel to the rotational axis of the drum, and defines a series of channels of increasing depth across the friction roller from an entry channel to an exit channel. Rope (14) feeds onto the drum through the entry channel in the friction roller and wraps around the drum between the drum and friction roller two or more times before exiting the drum through the exit channel. The friction roller slows load end (14A) of rope (14) on entry and speeds up haul end (14B) of the rope (14), thus acting as a load control mechanism and also assisting in preventing bunching of rope (14). The drum may be controlled to rotate in direction (A) only. Rope guide (16) and ascender cam (120) are also described.

Description

Improved pulley

Field of the Invention

This invention relates to an improved pulley apparatus.

Background of the Invention

Pulleys are used for raising and lowering objects and/or people. Pulleys may be used for lowering equipment or rescue workers from helicopters, and lowering equipment or workers down shafts. A typical standard pulley comprises a wheel or sheave with a grooved rim for carrying a line which wheel is rotatably mounted on an axle or the like and turns in a frame or block: pulling at one end of the line (the "haul" end) will raise a weight or object attached at the other end of the line. Often a sheave block is used with the pulley in a block and tackle type arrangement to create a mechanical advantage at the haul end. Standard pulleys run very freely. When very heavy loads are being lowered, the free running of the pulley is disadvantageous, as the operator on the haul end of the line, may have little control over the object at the other end of the line, particularly if the object is heavy, or if the object accelerates and starts to descend rapidly.

This control problem, can be overcome by fixing the wheel/sheave so that it is not able to turn and the rope merely slides over the surface of the sheave with the resultant increase in friction providing a greater degree of control for the operator. The sheave may comprise an elongate drum so that the line may be wrapped around the drum several times to increase the friction and consequently increase the ease of control. The problem with this approach however, is that although a greater degree of control is provided when lowering an object, the increase in friction makes it more difficult to raise an object using a fixed pulley.

A second problem which arises with pulleys, particularly fixed pulleys, is bunching of rope as it passes around the drum. Most ropes generally comprise a core and a mantle. The mantle is able to move slightly relative to the core. Bunching occurs when the mantle is compressed relative to the core. Bunching of the rope may occur due to friction forces acting on the exterior of the rope. Bunching is generally undesirable as it makes the raising and lowering of objects less smooth, and can also substantially increase the wear and tear on the rope and reduce the rope's useful life. A yet further problem which arises with pulleys, is the tendency for the ropes which are wrapped around the drum to rub against each other and ride up over each other.

The present invention seeks to alleviate some of the above mentioned problems of prior art pulleys.

Summary of the Invention

In a first aspect of the present invention, there is provided a pulley including a drum having a central axis mounted between two plates for receiving a rope passing around the drum, characterised by a friction roller spaced from and oriented generally parallel to the axis of the drum, the friction roller defining a series of channels and being rotatable about its central longitudinal axis characterised in that the depth of the channels increases gradually across the friction roller from the first or entry channel to the last channel, the arrangement being such that rope may be fed onto the drum via a first channel in the friction roller wrapped around the drum between the drum and friction roller two or more times exiting the drum, via the exit channel and wherein the friction roller slows the load end of the rope on entry, and tends to speed up the haul end of the rope relative to the load end. thus acting as a load control mechanism and also assisting in preventing bunching of the rope.

In a preferred embodiment the friction roller is driven by the drum by means of a suitable drive means such as a gear train.

A second aspect of the present invention, provides a pulley including a drum mounted between two plates including a rope guide or cover defining a at least a part of a generally helical path for rope to pass around the drum. the cross section of the path being a generally rounded channel adapted to receive a rope.

The guide path may define elongate apertures through which the rope may be seen but which are too narrow to allow a pulley rope having substantially the same diameter as the channel to pass through.

In a third aspect of the present invention, there is provided a pulley including a drum having a central axis, mounted between two side plates characterised in that the drum is mounted such that it is able to rotate about its central axis in one direction of rotation but not in the other, opposite, direction. Thus the third aspect of the present invention provides a pulley which can act as a static pulley having a fixed drum when an object is being lowered using the pulley, thus increasing the amount of control for the operator, whilst when the operator is raising a person or object on the pulley. the ability of the drum to freely rotate reduces the amount of work the operator has to do to raise the person or object.

In one particular embodiment of the third aspect of the invention, the drum may be mounted on an axle with a ratchet mechanism between the axle and drum, the axle being free to rotate in both directions about its longitudinal axis and wherein a locking means is provided for locking the axle, and when locked, the drum is able to rotate in one direction only. Alternatively a ratchet mechanism may be associated with a handle for the turning the axle.

Embodiments of the invention may incorporate all three aspects of the present invention.

In addition, a one way locking mechanism, such as an ascender cam. may be provided, which can be engaged when the pulley is being used to haul a load up. which will lock on and prevent slippage if the haul end of the rope is released.

Brief Description of the Drawings

A specific 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 perspective view from above of a pulley/winch embodying the present invention;

Figure la is a schematic drawing of a handle for the pulley/winch shown in Figure 1;

Figure 2 is a perspective view from below of the pulley shown in Figure 1: Figure 2a is a schematic drawing illustrating an axle lock for use with a particular embodiment of the pulley shown in Figure 2:

Figure 3 is a end view of the pulley shown in Figure 2:

Figure 3a illustrates a friction roller shown in Figure 3:

Figure 4 shows a cam mechanism for preventing accidental slippage of the rope: Figure 5 is a schematic drawing of a lower sheave block for the use with the pulley shown in Figures 1 to 3: and

Figure 6 illustrates a rope guide or cover.

Detailed Description of a Preferred Embodiment

Referring to the drawings. Figure 1 shows a pulley generally indicated at 10. The pulley includes a cylindrical drum 12. best seen in Figure 3. In Figure 1 and 3. the drum is obscured by a rope 14 which is wrapped around the pulley and by a rope guide 16. In Figure 3 the drum is partly obscured by the rope but is visible between turns of the rope. The drum 12 is mounted between two plates 18. 20. In the embodiment shown, two further plates 22, 24 are provided either side of plates 18. 20. However, in the preferred embodiment, further plates 22. 24 will not be required and plates 18. 20 will be enlarged. In the embodiment shown, the drum is mounted between the plates on a projecting axle 26 whose ends have a square cross section for receiving a winch handle 27 schematically illustrated in Figure la which defines a square aperture 27a which fits over the square end of the axle 26. The axle 26 and drum is free to rotate in either direction about its central axis. However, with reference to Figure 2A. an axle lock 28 is provided which includes a square cut out portion 30 at one end which can engage over the ends of the axle and prevent the axle from rotating. When the axle is locked, the drum can rotate in one direction only, as shown by the arrows A in Figure 1. As discussed above, the embodiment shown in Figure 1 includes an axle 26 which can spin either direction so that the pulley can be used with a manual winch handle or even an electric motor. The manual winch handle may be associated with a ratchet mechanism so that the handle can turn in one direction only. In alternative embodiments of the invention where the rope is simply controlled by controlling the haul end 14B of the rope and winch capabilities are not required, no projecting axle is provided and a ratchet mechanism is provided so that the drum only rotates in direction A. Thus, with reference to Figure 1. an object, not shown, attached to end 14A of the rope may be lowered by an operator controlling the haul end 14B. While the rope is being lowered, the weight attached to the rope and the forces of the rope acting on the drum, act on the drum in an anti-clockwise direction as oriented in Figure 1. However, the drum cannot rotate in that direction as it is only free to rotate in the clockwise direction A. Therefore, the drum being fixed, the rope slides on the drum creating friction and providing control to the person on the haul end 14B of the rope. However. when an object is to be raised, the tensile forces on the haul end 14 of the rope, pulling the object upwards, tend to cause the drum 12 to rotate in a clockwise direction which it is free to do. thus, the drum turns freely and less energy is wasted as friction and heat, and the object is easier to raise than if the drum were non-rota table. The pulley may be used with a lower pulley block 50. which also incorporates a drum 52 which may also be mounted so that it is rotatable about its axis in one direction only to complement the rotation of the pulley. Figures 5 and 6 illustrate in particular, the protective cover 54 which encases just over half the cylindrical surface of the drum 52. As can be seen, the cover 54 is used to guide the rope around the drum in a helical pathway. although the cover 54 only defines part of that pathway and does not enclose the drum totally. The cover includes a series of elongate slots 56 through which the rope can be seen to ensure that it is correctly wound on the drum. As best seen in Figure 6 when viewed in cross section, the guide defines a series of generally rounded channels 58 which receive the rope.

The construction of the guide 16 for the pulley is similar, although four channels are provided, not three.

A further novel feature of the pulley shown in Figure 1. is the provision of a friction roller 100 best seen in Figures 3 and 3a. The friction roller is mounted on an axle 101 and can rotate in either direction. The axle 101 is mounted on an arm 102. The ends 104 of the roller locate in apertures 106 in the plates 12 and 14. One end of the arm 102 is pivoted to the plates at 108. such so that the roller can move slightly away from the drum, although the range of movement is limited by the ends 104 of the roller coming into contact with the apertures 106 in the plate in which the ends are located. As is best seen in Figure 3. the friction roller defines four generally rounded channels which increase in size from the smallest 112 through channels of gradually increasing size 114. 116 to the deepest channel 118 at the opposite end of the friction roller. The function of the friction roller is to assist in maintaining the rope on the correct position on the drum, a job which is also performed in part by the cover, but more importantly, to eliminate bunching in the rope and improve rope control by slowing up entry of the rope onto the drum and speeding up the exit from the rope on the drum. That ensures that the resultant tension on the rope keeps the rope taut and eliminates bunching. The friction roller works due to the provision of channels of different depth and the fact that the surface of the shallowest channel 102 moves at the slowest speed and velocity compared to the bottom of the deeper channel 108. The slower channel is provided where the rope enters the drum and the faster channel where the rope leaves the drum so that the rope is slowed on entry to the drum and sped up on exit. Clearly, in practice, the rope cannot actually exit the drum quicker than it enters without breaking, so some slippage of the rope must be allowed for by movement of the friction roller away from the drum. To ensure that the friction roller turns with the drum, a gear train comprising a first gear wheel 103 having sixteen teeth is fixed to one end of the axle 26 of the drum meshing with a second gear wheel 105 having eight teeth fixed to one end of the axle 101 of the friction roller. The gearing is such that the friction roller turns at twice the angular speed of the drum.

The drum also includes an ascender cam 120, also illustrated in Figure 4. which can be activated when the rope is being used to haul an object upwards which will prevent the object from slipping if the haul end 14B of the rope is released.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are. therefore, to be considered in all respects as illustrative and not restrictive.

Claims

1. A pulley including a drum having a central axis, the drum being for receiving a rope passing around the drum, characterised by a friction roller spaced from and oriented generally parallel to the central axis of the drum. the friction roller defining a series of channels and being rotatable about its central longitudinal axis characterised in that the depth of the channels increases gradually across the friction roller from a first or entry channel to a last or exit channel, the arrangement being such that rope may be fed onto the drum via the first channel in the friction roller wrapped around the drum between the drum and friction roller two or more times exiting the pulley, via the exit channel in such a manner that the friction roller slows the load end of the rope on entry, and tends to speed up the haul end of the rope relative to the load end. thus acting as a load control mechanism and also assisting in preventing bunching of the rope.

2. A pulley as claimed in claim 1 further characterised by a one way locking mechanism which is engageable when the pulley is being used to haul a load upwardly using a rope, which is adapted to lock the rope and prevent slippage if the haul end of the rope is released.

3. A pulley as claimed in any one of claims 1 to 2 wherein the drum is mounted on an axle which is free to rotate in both directions about its longitudinal axis and wherein a locking means is provided for locking the axle, and when locked, the drum is able to rotate in one direction only.

4. A pulley as claimed any preceding claim characterised in that drive means extend between the drum and the friction roller for driving the friction roller when the drum rotates.

5. A pulley as claimed in claim 4 wherein the drive means is a gear train.

6. A pulley including a drum having a central axis, mounted between two side plates on an axle characterised in that the drum is mounted such that it is capable of rotation about its central axis in one direction of rotation but not in the other, opposite, direction.

7. A pulley as claimed in any preceding claim further including a rope guide or cover defining at least a part of a generally helical path for a rope to pass around the drum, the cross section of the path being a generally rounded channel.

8. A pulley as claimed in claim 2 wherein the rope guide defines elongate apertures through which the rope may be seen but which are too narrow to allow a pulley rope having substantially the same diameter as the channel to pass through.

9. A pulley as claimed in any one of claims 6 to 8 further characterised by a friction roller spaced from and oriented generally parallel to the central axis of the drum, the friction roller defining a series of channels and being rotatable about its central longitudinal axis characterised in that the depth of the channels increases gradually across the friction roller from the first or entry channel to the last channel, the arrangement being such that rope may be fed onto the drum via a first channel in the friction roller wrapped around the drum between the drum and friction roller two or more times exiting the drum, via the exit channel and wherein the friction roller slows the load end of the rope on entry, and tends to speed up the haul end of the rope relative to the load end. thus acting as a load control mechanism and also assisting in preventing bunching of the rope.

10. A pulley including a drum mounted between two plates including a rope guide or cover defining at least a part of a generally helical path for rope to pass around the drum, the cross section of the path being a generally rounded channel configured to receive a rope.

11. A pulley system including a pulley as claimed in any preceding claim and a lower pulley block which defines s drum which is mounted such that it is rotatable in one direction only.