GB2148835A - Winches - Google Patents

Abstract

A winch drum holding a mole winch cable 8 is mounted towards the rear of a trailer 1. The winch cable on leaving the drum 6 passes over the pulley of a sheave mounted on the lower end of a member 10 which may be lowered into a shaft to the depth of the mole run. The sheave is braced against the walls of the shaft by at least one reaction member 20 which thereby relieves forces created by tension in the cable which would otherwise have to be borne by the sheave supporting member 10 and the trailer, which therefore may be of lighter construction. <IMAGE>

Description

SPECIFICATION Mole winch The invention relates to a mole winch.

As an alternative to slit trenching methods of excavation for the installation and replacement of pipes and cables, moles are used to tunnel between small excavations spaced apart and the pipe, cable or like is laid from one to another without disturbing the ground surface above. This avoids the disruptions and inconveniences caused by continuous excavations and is altogether a cheaper cleaner and quicker method.

The mole is pulled through a pilot hole by a winched cable. Old pipe-work can be replaced by using a mole adapted to break-up the old pipe from the inside.

Working the mole requires powerful winch gear adapted to pull the winch cable along the line of the mole-run with a force of up to several tons. Moreover, because of the faster working the winch gear needs to be moved from one site to another frequently. For mobility it is preferred that as much of the winch gear as possible remains above ground level and is mobile, but that it shall be stationary and stable during winching operations. Thus, existing equipment tends to be of very sturdy construction and consequently very heavy.

An object of the present invention is to provide equipment which is much lighter and yet at least as stable and capable of exerting the same pulling forces on the mole.

According to the present invention there is provided a mole winch comprising a winch drum, a winch cable, a vertically adjustable member carrying at one end a sheave over which the cable passes from the drum to the mole, and at least one reaction member which braces the sheave end of the vertical member against tensile forces in the winch cable.

Preferably each reaction member is adjustable for length, and has at its distal end a load spreading foot.

A preferred embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings in which: Figures 1 and 2 show side and end views respectively of the complete winch gear equipment mounted on a trailable chassis, in the moveable position, and Figure 3 shows a side view of part of the equipment deployed to the winch position.

The equipment of Figures 1 and 2 comprises a trailer chassis 1 fitted with a drawbar 2, roadwheels 3, a rectractable jockeywheel 4, at the front of the chassis 1 adjacent of the drawbar 2, and at the rear of the chassis a pair of screwjacks 5, one at either side of the chassis.

A winch drum, generally indicated by reference 6, is mounted towards the rear of chassis 1 about a horizontal axis 7 lying at right angles to the longitudinal direction of the chassis. A winch cable 8 is paid out downwardly from the drum through an open part of the chassis framework. Immediately behind the drum 6, and placed centrally in the chassis 1 is a fixed open ended housing 9 mounted with its axis vertical. This housing 9 has a rectangular internal section of constant width throughout the height of the housing. A longitudinal member 10, also having a rectangular cross section constant along its length and which fits closely within the housing 9, is slideably engaged with the housing 9 for vertical movement relative thereto.Opposite sides of the housing 9 are provided drilled apertures 11 to receive a securing pin 12, the corresponding wider sides of the longitudinal member 10 are also provided with apertures 13, spaced apart at intervals along its length, to receive the pin 12.

The lower end of member 10 carries a sheave block 14 comprising a pulley wheel 15 rotatably mounted between two side members 16, 17 welded to the member 10. On leaving the winch drum 6 the winch cable 8 is lead over the pulley wheel 15, running off to the mole from the lower quadrant.

A relatively short cylindrical sleeve 18, 19 is mounted on each of the side members 16, 17 on either side of sheave block 14, with their respective axes horizontal and in the same plan as the final run of cable 8 from the pulley wheel 15 to the mole (not shown).

Referring now to Figure there is shown a reaction member 20 comprising a rod or tube of constant circular cross-section which fits closely within the cylindrical sleeve 18. The sleeve 19 also carries a similar reaction member on the opposite side of the sheave 14. The distal end of member 20 is provided with a load spreading foot 21, which may be of any convenient or desired shape, but in the presently described example consists of a circular pad which is fixed at right angles to the end of the member 20.

The other side of foot 21 is provided with at least one tine 22, which in this example comprises a centrally located spike. The reaction member may alternatively have any convenient cross section for example rectangular or square.

In operation, the above described equipment is towed behind a vehicle in the configuration shown in Figures 1 and 2. In preparation for the use of a mole a shaft like excavation will have been prepared to the required depth. The trailer chassis 1 is then positioned adjacent the excavation such that the vertical member 10 may be lowered so that the final run of cable 8 from sheave 14 to the mole is roughly at the required depth. The member 10 is lowered with respect to housing 9 until apertures 13 in the member 10 are aligned with apertures 11 in the housing 9 and then secured in this position by insertion of pin 12. Final adjustment may be carried out if necessary by adjustment of the height of screwjacks 5, which are normally lowered to support the chassis 1 in position during winching.The reaction members 20 are then fitted within the sleeves 18,19 and adjusted for length, so that the feet 21 engage a sidewall of the excavation on either side of the path ofthe mole run.

The positions of sleeves 18, 19 are such that the reaction members 20 are parallel to the mole run and equidistantly spaced on either side. Preferably the axes of the tubes 18, 19 are angled so that the feet 21 at the distal ends of the reaction members are splayed and the winch cable bisects the angle between them. The reaction members 20 are also preferably telescopically adjustable with respect to their mounting sleeves 18, 19.

During winching operations the vertical member 10 experiences a bending moment in the direction of winch cable tension. Prior art winching equipment of this type requires, for the member 1 Oa, strong beam of substantial cross section. In contrast, in the invention because the lower end of the beam 10 is supported at the sheave 14 much of the bending moment is transferred to the walls of the excavation by the reaction members 20. Therefore, the member 10 is of much lighter construction and maybe of smaller cross section. The reaction members 20 also relieve much of the forces which otherwise would need to be absorbed by the trailer which is now subjected to only small horizontal forces which are easily countered by the trailer brakes and supporting jacks 5 with no need for additional ground engaging trailer mounted spikes or the like.

Claims (8)

1. A mole winch comprising a winch drum, a winch cable, a vertically adjustable member carrying at one end a sheave over which the cable passes from the drum to the mole, and at least one reaction member which braces the sheave end of the vertical member against tensile forces in the winch cable.

2. A mole winch as claimed in Claim 1 wherein each reaction member is adjustable for length.

3. A mole winch as claimed in Claim 2 wherein a reaction member is carried by a sleeve fixed to the sheave and axially adjustable therein.

4. A mole winch as claimed in any preceding claims wherein a reaction member has at its distal end a load spreading foot.

5. A mole winch as claimed in Claim 4, wherein the load spreading foot has at least one tine.

6. A mole winch as claimed in any preceding claim wherein there are two reaction members mounted to either side of the sheave.

7. A mole winch as claimed in claim 6 wherein the two reaction members are splayed towards their distal ends so that the winch cable passes equidistantly between them.

8. A mole winch substantially as hereinbefore described with reference to the accompanying drawings.