GB2140764A

GB2140764A - Improvements in or relating to winches

Info

Publication number: GB2140764A
Application number: GB08410656A
Authority: GB
Inventors: John Thomas Hird Webb
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-04-27
Filing date: 1984-04-26
Publication date: 1984-12-05
Also published as: GB8410656D0

Abstract

A winch in which rotation is transmitted from a motor (6) to a capstan (1) includes a planet gear (11), which rotates normally about a first axis only. If, because of a sudden increase in cable tension, the capstan (1) tends to resist rotation or to rotate more quickly than the planet gear (11), the excess motion of the motor (6) or the capstan (1) is taken up in rotation of the planet gear (11) about a second axis, which is the axis of rotation of a sun gear (10), against the action of damping means comprising a rack and pinion arrangement, the rack (3) being fixed to the piston (4) of a fluid operated piston and cylinder arrangement. <IMAGE>

Description

SPECIFICATION Improvements in or relating to winches This invention relates to improvements in or relating to winches.

This invention provides a winch comprising drive means, rotatable bearing means for a cable, means for transmitting motion from the drive means to the bearing means so as to effect rotation of the bearing means at a predetermined velocity, the transmission means including means movable in response to rotation of the bearing means at a velocity other than the predetermined velocity and means for damping and/or boosting the said movement of the said movable means.

The invention further provides a winch in which rotation is transmitted from a drive means, such as a motor, to a capstan via a gear which is rotatable about first and second axes, rotation about the second axis being damped. Normally, the gear rotates about the first axis only. If, because of a sudden increase in cable tension, the capstan tends to resist rotation or to rotate more quickly than the gear, the excess motion of the capstan or the drive means is taken up in rotation of the gear about the second axis, against the action of the damping means.

The damping means may comprise a rack and pinion arrangement, the rack being fixed to the piston of a pneumatic or hydraulic piston and cylinder arrangement.

The gear may comprise the planet gear of an epicyclic gear train comprising a sun gear fixed to a motor drive shaft, a planet gear and an internal gear of the capstan, the planet gear being rotatable on a shaft which is itself rotatable about the axis of rotation of the sun gear.

For a better understanding of the present invention, and to show how the same may be put into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a side elevational view of a twincapstan winch in accordance with the invention, Figure 2 is a cross-sectional view taken along the line ll-ll of Fig. 1, Figure 3 illustrates the path followed by a cable guided by the twin-capstan winch of Figs. 1 and 2, Figure 4 is a cross-sectional view of a drum winch in accordance with the invention, and Figure 5 is a cross-sectional view of a piston and cylinder arrangement which is suitable for use with the twin-capstan winch of Figs. 1 to 3 or the drum winch of Fig. 4.

Referring now to the drawings, Fig. 1 shows a winch having twin capstans 1 each of which can cooperate through the intermediary of a pinion 2 with two racks 3 each of which is fixed to the piston 4 of a hydraulic piston and cylinder arrangement 5.

As can be seen in Fig. 2, each capstan 1 is adapted to be driven in rotation by means of a motor 6, a pinion 7 fixed to a drive shaft 8 of the motor 6, a reduction gear 9 which meshes with the pinion 7 and an epicyclic gear train comprising a sun- gear 10, a planet gear 11 and an internal gear 1 2 provided on the inner surface of the capstan 1. The sun gear 10 is fixed to the reduction gear 9 by means of a shaft 1 3 and the planet gear 11 is rotatable on a shaft 14 of a planet carrier 1 5. The pinion 2, which is coaxial with the reduction gear 9 and the sun gear 10, is fixed to the planet carrier 1 5 and meshes with the racks 3.

In use of the twin-capstan winch, any rotation of the two pinions 2 is normally prevented by friction between the pinions 2 and the racks 3 and by the tendency of the pistons 4 to resist motion in their respective cylinders. Therefore, rotation of the sun gears 10 is transmitted solely to the internal gears 1 2 of the capstans 1. However, whilst cable is - being winched in, the tension in the cable may suddenly increase, for example because of relative movement between a wharf on which the winch is being used and a vessel to which the cable is connected. The capstans 1 therefore resist rotation and, as a result, rotation of each sun gear 10 causes the respective planet gear 11 to travel around the axis of rotation of the pinion 2, effecting rotation of the planet carrier 1 5 and the pinion 2.

Similarly, if, whilst paying out cable there is a sudden increase in cable tension, the rate of rotation of the capstans 1 increases, and this increase is taken up in rotation of each planet carrier 1 5 in the same direction as the associated capstan 1. In each case, there is rotation of the pinions 2 which causes the racks 3 to move the pistons 4 into or out of their respective cylinders. A suitable pressure of hydraulic fluid is maintained in each cylinder to damp rotation of the pinions 2. For example, if, during winching in, an increase in cable tension would cause each piston 4 to move into its respective cylinder, the space behind the piston 4 should be connected to a pump and to a sink of the hydraulic circuit during winching in and paying out, respectively.

Turning now to Fig. 4, a drum winch comprises a drum 16 which is drivable in rotation by means of a motor 17, a motor drive shaft 18 and an epicyclic gear train comprising a sun gear 19, a planet gear 20 and an internal gear 21 of the winch drum 16. The sun gear 1 9 is fixed on the motor drive shaft 18 and the planet gear 20 is rotatably mounted on a shaft 22 of a planet carrier 23. A pinion 24 is fixed to the planet carrier 23 for rotation on a common axis with the motor drive shaft 1 8 and meshes with a rack 25 which is fixed to a piston 26 of an hydraulic piston and cylinder arrangement 27. The drum winch operates in a substantially similar manner to the twincapstan winch described above with reference to Figs. 1 to 3.

Referring now to Fig. 5, there is shown an alternative piston and cylinder arrangement for use with the twin-capstan winch of Figs. 1 to 3 or the drum winch of Fig. 4, comprising a cylinder 28 and a piston 29, having a first piston head 30 and a second piston head 31 which define therebetween a fluid tight chamber 32 of constant volume. This chamber 32 is divided into two, smaller, chambers 33, 34 by a partition 35 which is fixed to the cylinder 28 and through which the piston 29 slidably extends. The fit between the partition 35 and the piston 29 is not fluid tight, so that hydraulic fluid can pass slowly from one of the two chambers 33, 34 to the other. The cylinder 28 is provided with three ports 36, two of which open into the space behind the first piston head 30 and the chamber 33 between the first piston head 30 and the partition 35, respectively, and are connected to a hydraulic fluid source under pressure provided with a directional control valve or swash plate pump, and the third of which opens into the chamber 34 between the second piston head 31 and the partition 35 and is connected to a reservoir or sink for hydraulic fluid. Thus, any movement of the piston 29 into or out of the cylinder 28 is resisted by hydraulic fluid pressure.

Claims

1. A winch comprising drive means, rotatable bearing means for a cable, means for transmitting motion from the drive means to the bearing means so as to effect rotation of the bearing means at a predetermined velocity, the transmission means including means movable in response rotation of the bearing means at a velocity other than the predetermined velocity and means for damping and/or boosting the said movement of the said movable means.

2. A winch according to Claim 1, wherein the transmission means comprises a gear which is rotatable about a first axis for transmitting rotation from the drive means to the bearing means and about a second axis in response to rotation of the bearing means at a velocity other than the predetermined velocity, rotation about the second axis being that which is damped and/or boosted.

3. A winch according to Claim 2, wherein the gear is the planet gear of an epicyclic gear train comprising a sun gear rotatable by the drive means, a planet gear and an internal gear of the bearing means, the first axis being the axis of rotation of the planet gear and the second axis being the axis of rotation of the sun gear.

4. A winch according to Claim 2 or 3, wherein the damping and/or boosting means comprises a rack and pinion arrangement, the pinion being rotatable about the second axis.

5. A winch according to any one of the preceding claims, wherein the damping and/ or boosting means comprises a fluid operated piston and cylinder arrangement.

6. A winch according to Claims 4 and 5, wherein the rack is fixed to the piston of the piston and cylinder arrangement.

7. A winch, substantially as hereinbefore described with reference to, and as shown in, Figs. 1 to 3 of the accompanying drawings.

8. A winch, substantially as hereinbefore described with reference to, and as shown in, Fig. 4 of the accompanying drawings.

9. A winch, substantially as hereinbefore described with reference to, and as shown in, Figs. 1 to 3 and 5 of the accompanying drawings.

10. A winch, substantially as hereinbefore described with reference to, and as shown in, Figs. 4 and 5 of the accompanying drawings.

11. Any novel feature or combination of features described herein.