WINCH

Abstract: A winch intended for mounting at ground level over a vertical shaft communicating with an underground duct, and for drawing equipment through the duct using a chain, comprises a pair of rams (10, 12) coupled together in a parallel spaced apart relationship by a first chain gripper assembly (16) mounted on the ram cylinders, and a second gripper assembly (22) mounted on the ends of the ram pistons (20). Each gripper assembly (16, 22) has a central passageway for receiving a chain disposed between and parallel to the rams (10, 12), each passageway having associated therewith a respective pair of pivotable clamping jaws which act to prevent relative downward movement of the chain but to allow relative upward movement of the chain. When the rams (10, 12) are reciprocated first one, then the other gripper assembly clamps the chain so that with repeated reciprocation the chain is caused to move upwards in a stepwise manner. A pivotal mounting device (14) defining two axes of rotation with respect to the supporting base structure allows the rams (10, 12) automatically to take up a position parallel to the chain obviating the need for accurate positioning of the winch.

Description: WINCH This invention relates to a winch intended primarily for drawing apparatus through an underground duct. In my co-pending British Patent Applications Nos. 83 15982 and 83 33567 I disclose devices for enlarging or removing irregularities in an underground duct such as a sewer pipe, and for towing a plastics lining pipe to line the duct after the device has passed through it. In a preferred mode of operation the profiling or enlarging of the duct is carried out partly by drawing the device through the sewer with a winch positioned at a manhole and by repeatedly expanding and retracting a plurality of leaf members at the front of the device to force the wall of the sewer outwards. To haul the device and lining pipe sections through the sewer a pulling force is applied via chains by a powerful winch of con¬ ventional design situated at ground level adjacent the manhole, or by a winch in the form of a reciprocating hydraulic ram and ratchet system at the base of the manhole. A conventional drum winch of sufficient power has the disadvant¬ age of being large and relatively expensive. Due to its size, it can be difficult to position the winch directly over the manhole, which means that a pulley or roller must be securely fixed at the edge of the manhole to bring the chain laterally away from the manhole entrance to the winch. The alternative solution of using a reciprocating hydraulic ram at the bottom of the manhole has the disadvantage that the ram and its supporting structure obstructs the entrance to the sewer pipe so that the pipe enlarging device cannot be pulled out of the pipe by the ram. It is also difficult, and in some circumstances dangerous, to obtain access to the ram should a fault occur. It is an object of the present invention to provide an improved winch which can be considerably smaller and less costly than a drum winch, yet can be located at ground level without requiring pulleys or rollers at the manhole entrance. According to a first aspect of this invention a winch comprises a base structure, at least one fluid driven ram pivotally mounted on the base structure and having a cylinder and a piston, a first gripper assembly associated with the cylinder, and a second gripper assembly associated with the piston, each gripper assembly having means for clamping and releas- ing a tensioned towing element on alternate strokes of the ram. The towing element is preferably a chain which is engaged by pivot- able jaws in each gripper assembly, each jaw being shaped to match the shape of the links of the chain. The base structure may comprise a mounting bracket for securing the winch to the tail of a vehicle or it may be a ground supported frame, the vehicle tail or the frame respectively being positioned over, for example, a manhole communi¬ cating with a sewer pipe. The pivotal mounting of the ram allows it to adopt a required orientation approximately parallel to the chain. A winch of this kind has the advantage of having a start-up pulling force equal to its maximum pulling force. It also has the ability to inch the chain over very small distances at a time by hydraulic control. According to a second aspect of the invention, there is provided a method of drawing equipment through an underground duct which communicates with a vertical shaft extending to ground level, characterised by the steps of providing in the shaft a towing element connected to the equipment in the duct, placing a towing element support in the shaft adjacent the end of the duct, providing at the top of the shaft a winch comprising a base structure, a fluid driven ram mounted on the base structure, first and second gripper assemblies for alternately clamping and releasing the towing element, passing the towing element around the said support and through passageways in each of the gripper assemblies, and reciprocating the ram to produce repeated relative movement of the gripper assemblies towards and away from each other so that the towing element is clamped alternately on opposite strokes of the ram thereby to move the towing element through the winch and draw the equipment through the duct. According to a third aspecτ of the invention, there is provided a winch comprising a base structure, a fluid driven ram pivotably mounted on the base structure, first and second gripper assemblies each for alternately clamping and releasing a towing element, the ram being arranged to produce relative movement between the gripper assemblies so that, as the ram is reciprocated repeatedly, the towing element is clamped and released alternately by one assembly then the other thereby moving the element relative to the winch in a required direction. The invention will now be described by way of example with reference to the drawings in which:- Figure 1 is a perspective side view of a first winch in accord¬ ance with the invention; Figure 2 is a perspective view of the winch of Figure 1 looking from the rear; Figure 3 is a diagram of an operative arrangement in accordance with the mehtod of this invention showing the winch of Figures 1 and 2 mounted on the tail of a vehicle and coupled to a chain in the entrance to a manhole; Figure 4 is a rear view of the top portion of the winch of Figures 1 and 2 with covers removed to show the disposition of the chain in the winch; Figure 5 is a side view of a second embodiment of winch in accordance with the invention; Figure 6 is a simplified rear view of the winch of Figure 5; Figure 7A is a side view of a pivotal mounting device forming part of the winch of Figures 5 and 6; and Figure 7B is a plan view of the pivotal mounting device of Figure 7A. Referring to Figures 1 and 2, a first winch in accordance with the invention has a pair of parallel, spaced apart fluid driven rams 10 and 12 which, in the normal operative arrangement of the winch, are generally upright as shown. A pivotal mounting device 14 is secured to a first gripper assembly 16 comprising a transverse member which houses the upper ends of the ram cylinders and holds the latter in their spaced apart relationship. The lower ends of the ram cylinders are interconnected by a transverse roller assembly 18. The upper ends of the ram pistons 20 carry a second gripper assembly 22 again comprising a transverse member virtually identical to the transverse member of the first gripper assembly 16. - A - Referring now to Figure 3, in a typical operative arrangement, the winch 24 is mounted on a vehicle 26 over a manhole 28. A forwardly extending mounting shaft 14A (Figure 1) is pivotally secured in a socket in a base structure or rear mounting plate 30 fixed to the vehicle 26 so that the winch is free to rotate about an approximately horizontal axis in the manhole entrance. A towing element in the form of a chain 32 connected to equipment (not shown) such as a sewer enlarging device in a sewer pipe 34, passes around a support fixed in the manhole adjacent the end of the sewer pipe 34 and having a roller or pulley 36, rises directly to the winch 24 where it passes through passageways in the two gripper assemblies 16, 22 to emerge loose from the top of the second gripper assembly. Each gripper assembly is arranged, as will be explained below, to clamp the chain 32 to prevent downward movement, but to release the chain to allow upward movement. Thus, when the winch is operated by reciprocating the rams, the chain 32 is tensioned and moved upwardly on each upward stroke of the rams. When the chain 32 is tensioned the winch rotates firstly about the horizontal axis defined by shaft 14A and secondly about a second horizontal axis perpendicular to the first defined by bearing 14B in the pivotal mounting device 14 (Figure 1), so that the rams take up a position in which they are generally parallel to the chain 32. The roller 18 (Figure 1) prevents the lower part of the winch swinging towards the vehicle, since the chain engages it on its forward side (i.e. the chain passes to the right of the roller 18 as seen in Figure 3). The construction of the gripper assemblies 16, 22 is seen more clearly in Figure 4. Each comprises a transverse bar defining a central passageway 16A, 22A for the chain 32, and each has a pair of pivotally mounted clamping jaws 40, 42 and 44, 46. These jaws are normally held in place by cover plates 48, 50 which are shown in Figure 2 but which have been removed in Figure 4 to show the internal construction of the gripper assemblies. Each jaw has a shaped outer end portion with recesses corresponding to the shape of the links of the chain, the end portions being attached to respective arms 40A, 42A, 44A, 46A, which are drilled to receive respective pivot pins housed in the respective transverse member. In Figure 4 these pivot pins are not shown because they have been removed with the cover plates 48, 50. The jaws are shown in their fully open raised positions, so that the chain is free to run in either direction through the pass¬ ageways 16A, 22A. However when the jaws are allowed to pivot down¬ wards under the influence of gravity the end portions move inwardly towards the passageways and against stop surfaces 52, 54, 56, 58 to clamp the chain to prevent it moving downwards. Of course, the jaws are still free to pivot upwards to a release position when the movement of the chain relative to the jaws is upwards so that each pair of jaws acts as a ratchet. It will be seen from Figure 4 that each jaw has a cylindrical surface 40B, 42B, 44B, 46B at its inner end which abuts a corresponding concave surface in the respective transverse member so as to avoid excessive thrust forces being applied to the pivot pins when the jaws are clamping the chain 32. It will be understood that, as an alternative to the configuration shown in Figure 4, the jaws can be shaped and mounted so as to clamp the chain 32 when they are inclined upwardly from the horizontal stop surfaces if required. The cover plates 48, 50 (Figure 2) are easily accessible, allowing straightforward access to the jaws for maintenance. Although the embodiment shown in Figures 1 to 3 operates satis- factorily in most situations, there are occasions when it is inconvenient to use a vehicle with its tail jacked by jack 60 as shown in Figure 3. Referring now to Figures 5, 6 and 7, an alter¬ native embodiment incorporates a base structure in the form of a ground supported frame 62 which is designed simply to be placed partly over a manhole. In this embodiment the rams 10, 12 are supported on a yoke 64 which has a forwardly extending shaft 64A rotatably housed in a tube 66 welded to an upper cross member 62A of the frame 62 and defining a first rotation axis inclined at 15° to the horizontal. A second axis of rtoation is defined by half round bars 68 (Figure ' 6) welded to the underside of the first gripper assembly 16. These locate in cylindrical grooves 70 cut in the arms 64B (Figure 7) of the yoke 64 as shown in Figures 7A and 7B. As with the first embodiment, provision of these two axes of rotation allows the rams to take up positions approximately parallel to the chain 32, so that accurate placing of the frame 62 is not important. The shaft 64A of the yoke has a cross bore 64C for receiving a retaining pin (not shown) to prevent the yoke from sliding unintentionally out of the tube 66. In this embodiment the lower stabilising roller 18 of the first embodiment is unnecessary since the second, transverse axis of rotation defined by the bars 68 passes through the chain axis. In other respects, the winch of the second embodiment, more specifically the arrangement of the rams 10, 12 and the gripper assemblies 16, 22 is similar to that of the first embodiment. The present invention is not restricted to a winch for use with a chain, but extends also to one for use with a cable, wire or rope, the gripping assemblies being modified accordingly to achieve the same clamping function as described above with reference to a chain.

Claims: CLAIMS : 1. A winch comprising a base structure, at least one fluid driven ram pivotally mounted on the base structure and having a cylinder and a piston, a first gripper assembly associated with the cylinder, and a second gripper assembly associated with the piston, each gripper assembly having means for clamping and releasing a tensioned towing element on alternate strokes of the ram. 2. A winch according to claim 1, wherein the towing element is a chain, and each gripper assembly has at least one clamping jaw shaped to correspond to the shape of the links of the chain. 3. A winch according to claim 1, characterised in that the pivotal mounting device defines two generally perpendicular pivot axes. 4. A winch according to claim 1, characterised by a pair of fluid driven rams arranged in a parallel spaced apart relationship, and characterised in that the first and second gripper assemblies include respectively first and second cross members inter-connecting respectively the cylinders of the rams and the pistons of the rams and define respective central passageways for receiving the towing element. 5. A winch according to claim 1, characterised in that each gripper assembly has a pair of movable clamping jaws. 6. A winch according to claim 4, characterised in that each gripper assembly further includes a pair of clamping jaws mounted on opposite sides of the respective passageway, each jaw being pivotable towards the passageway from a release position to a clamping position in which the jaw engages a stop. 7. A winch according to claim 1, characterised in that the winch is supported solely by said pivotal mounting device. 8. A winch according to claim 7, characterised in that said pivotal mounting device engages the first gripper assembly. 9. A method of drawing equipment through an underground duct which communicates with a vertical shaft extending to ground level, characterised by the steps of providing in the shaft a towing element connected to the equipment in the duct, placing a towing element support in the shaft adjacent the end of the duct, providing at the top of the shaft a winch comprising a base structure, a fluid driven ram mounted on the base structure, first and second gripper assemblies for alternately clamping and releasing the towing element, passing the towing element around the said support and through passageways in each of the gripper assemblies, and reciprocating the ram to produce repeated relative movement of the gripper assemblies towards and away from each other so that the towing element is clamped alternately on opposite strokes of the ram thereby to move the towing element through the winch and draw the equipment through the duct. 10. A winch comprising a base structure, a fluid driven ram on the base structure, first and second gripper assemblies each for alternately clamping and releasing a towing element, the ram being arranged to produce relative movement between the gripper assemblies so that, as the ram is reciprocated repeatedly, the towing element is clamped and released alternately by one assembly then the other thereby moving the element relative to the winch in a required direction.

Inventors: YARNELL IAN ROLAND, YARNELL, IAN, ROLAND
Applicants: YARNELL IAN ROLAND, YARNELL, IAN, ROLAND
Application year: 1985
Main classification: B66D3
IPC codes: B66D3