GB2295412A - Mechanism for raising and lowering a paddle in a sluice, weir or lock-gate. - Google Patents

Abstract

A mechanism 10 for raising and lowering a paddle in a sluice, weir or lock-gate comprising operating means to move the paddle between fully raised and fully lowered positions, and means to prevent the free-fall of the paddle under gravity to its fully lowered position. The means preventing free-fall comprises a brake which operates on a transmission shaft 13, the brake comprising a ratchet 17 and pawl 22 and means 16, 18 to clamp the ratchet to the shaft whilst the paddle is being raised and to release the ratchet such that the shaft may rotate with respect to the ratchet whilst the operating means is operated to lower the paddle. <IMAGE>

Description

Title: Mechanism for raising and lowering a paddle in a sluice, weir or lock-gate.

Description of Invention The invention relates to a mechanism for raising and lowering a paddle in a sluice, weir, or lock-gate for use on canals, rivers and the like.

Canal and river locks permit the raising and lowering of boats between stretches of water at different levels. In order to do so, the flow of water into the lock from the higher level and out of the lock to the lower level is controlled by means of paddles. The paddles are located either on the gates at the top and bottom of the lock or in sluices through the ground adjacent to the lock.

In some situations, on larger rivers and canals, locks are operated by professional personnel and may be automated. However, in general on canals in the UK locks are operated by the crews of the boats passing through them. This is done by temporarily attaching a lock handle, known as a windlass, to a winding point and winding the paddle up via a gear mechanism. A pawl and ratchet mechanism is provided to retain the paddle in the fully raised or any partially raised position as required. To lower the paddle, the pawl and ratchet is released and the paddle should be lowered in a controlled fashion, if damage to the mechanism and injury to the operator and bystanders is to be avoided. However, this demands that the operator resists the force of gravity acting on the paddle, which in general is heavy, by resisting the rotation of the windlass.If the operator's grip on the windlass is lost, the paddle will fall causing the windlass to rotate rapidly which may injure the operator, or the windlass may fly off and injure the operator or bystanders. In addition this can cause breakages in the paddle operating mechanism.

It is an object of the present invention to provide an improved mechanism for raising and lowering a paddle in a sluice, weir or lock-gate which alleviates the above identified problems.

The present invention therefore provides a mechanism for raising and lowering a paddle in a sluice, weir or lock-gate comprising operating means to move the paddle between fully raised and fully lowered positions, and means to prevent the free-fall of the paddle under gravity to its fully lowered position.

Preferably, the operating means comprises a manually operable member, and a transmission to transmit drive to the paddle. The transmission may comprise a shaft carrying a gear which meshes with a drive element fixed to the paddle. The means to prevent free-fall of the paddle may comprise a brake which operates on the shaft at all times but which, whilst the operating means is operated to lower the paddle, is permitted to slip allowing the paddle to lower under gravity in a controlled fashion.

Preferably, the transmission does not transmit drive from the paddle to the manually operable member during lowering of the paddle.

The brake may comprise a ratchet and pawl, the pawl being engaged with the ratchet to prevent rotation of the ratchet in the first direction and, means to clamp the ratchet to the shaft whilst the paddle is being raised or is in a raised condition and to release the ratchet such that the shaft may rotate with respect to the ratchet and the paddle may lower whilst the operating means is operated to lower the paddle.

The means to clamp the ratchet to the shaft may comprise a shoulder on the shaft, a threaded portion of the shaft carrying the ratchet and a gear driven by the manually operable member, arranged such that when the operating means is operated to raise the paddle, the gear and ratchet are moved along the threaded portion of the shaft and the ratchet clamped against the shoulder such that the pawl prevents the shaft rotating in the first direction, and when the operating means is operated to lower the paddle, the gear and ratchet move along the threaded portion of the shaft away from the shoulder permitting the shaft to rotate in the first direction and the paddle to lower.

An example of a mechanism according to the invention will now be described, by way of example only, with reference to the accompanying drawing which is a horizontal section through a water control paddle operating mechanism according to the invention.

A water control paddle (not shown) is operated by means of a mechanism 10 enclosed within a casing 11. The casing 11 comprises a first wall 1 1L a second wall 1 lb and a gear cover 11s, A primary shaft 12 and a secondary gear shaft 13 are each supported adjacent a first end by the first wall of the casing 11a via bearings, and adjacent a second end by a second wall of the casing 11b also via bearings. The primary shaft 12 and secondary gear shaft 13 are each rotable with respect to the casing 11.

A manually operable member in the form of a spindle 14 is attached to the first end of the primary shaft 12 where the shaft 12 protrudes through the first wall 1 lea of the casing 11. A primary spur gear 15 is attached to the second end of the primary shaft 12 where it protrudes through the second wall 11h of the casing 11.

The secondary gear shaft 13 has adjacent its second end, and outwardly of the second wall ill of the casing 11, a shoulder 16, a ratchet 17, a secondary spur gear 18, a thrust bearing 19, and a retaining mechanism 20. The shoulder 16 may be formed integrally with the shaft 13 or may be splined thereto or otherwise provided thereon. The ratchet 17 and secondary spur gear 18 are located on a threaded portion 21 of the gear shaft 13 and bear screw threads which engage the thread on the shaft. The bearing 19 is arranged to rotate with the shaft 13 whilst the retaining mechanism 20 retains the ratchet 17, secondary spur gear 18 and stop 19 on the shaft 13. The secondary spur gear 18 is meshed with the primary spur gear 15.The operating mechanism 10 further comprises a pawl 22 which is pivoted on a pin 23 located in the second wall of the casing 11h such that the pawl 22 engages with the ratchet 17 to prevent the ratchet rotating anti-clockwise.

The portion of the secondary gear shaft 13 between the first and second walls 11a.11h of casing 11, bears a pinion gear 24 splined or otherwise fixed to shaft 13 for rotation therewith. The pinion gear 24 meshes with a rack 25 to which the paddle (not shown) is fixed.

The gear cover 11g obscures the second ends of the primary and secondary shafts 12,13, from view when the mechanism 10 is in use. Thus all components, except for the spindle 14, are contained within the casing 11. This protects the mechanism 10 from damage, accidental or otherwise, and prevents injury to operators or bystanders who could otherwise get caught in the mechanism.

The manner of operation of the mechanism 10 will now be described, where all motions of rotation are described as viewed in the direction of arrow A as shown on the figure.

A lock handle (not shown), also known as a windlass, is attached to the spindle 14 which in general has a square cross section tapering towards its free end. The windlass is rotated such that, in this example, the shaft 13 is turned anticlockwise, thus rotating the primary spur gear 15 anti-clockwise and the secondary spur gear 18 clockwise.

Of course in another arrangement, the mechanism may be operated upon rotation of the windlass clockwise, with the other components of the mechanism being arranged to operate appropriately.

Due to the thread 21 on the shaft 13, this rotation of the secondary spur gear 18 causes the gear to travel to the left of the figure along the threaded portion of the gear shaft 13 until it comes into contact with ratchet 17. Thus forces ratchet 17 against the shoulder 16 locking the ratchet 17 between the secondary spur gear 18 and the shoulder 16. Thus, as a result of this clamping force, the secondary spur gear 18, ratchet 17, and shoulder 16 effectively become one and the gear shaft 13 is then driven clockwise by the rotation of the windlass.

This action rotates the pinion gear 24 to raise the rack 25 and thus the paddle (not shown).

The paddle is retained at whatever height it is raised to by means of the pawl 22 engaging with the ratchet 17 and preventing rotation of the gear shaft 13. The ratchet 17 cannot rotate in an anti-clockwise direction because the pawl 22 prevents it doing so. Thus the combination of the shoulder 16, ratchet 17 and pawl 22 form a brake when the ratchet is locked against the shoulder.

To lower the paddle, the windlass and the primary shaft 12 are turned clockwise. Thus the primary spur gear 15 is rotated clockwise and the secondary spur gear 18 rotates anti-clockwise. This action causes the secondary spur gear 18 to move along the screw threaded portion 21 of the gear shaft 13, to the right in the figure, away from the ratchet 17. This releases the ratchet 17 from the clamping force and disconnects the driving connection between the gear shaft 13 and primary shaft 12. Thus the paddle and the rack 25 may start to fall under their own weight but in doing so, do not drive the primary shaft 12 and hence do not rotate the windlass. However, the gear shaft 13 rotates anti-clockwise and the secondary spur gear 18 is wound back to the left in the figure, again clamping the ratchet 17 against the shoulder 16 and forming a brake.Hence, the connection of the secondary spur gear 18, ratchet 17 and shoulder 16 by means of the clamping force can only be "broken" if the secondary spur gear 18 is rotated faster than the gear shaft 13 rotates under the weight of the paddle and rack 25. If the gear shaft 13 rotates faster than the secondary spur gear 18 is rotated, the clamping force is re-applied and the descent of the paddle stopped.

Thus the mechanism 10 allows controlled lowering under gravity of the paddle and rack 25 but not free fall. In essence, rotation of the spindle 14 and hence of the primary shaft 12 reduces the clamping force and permits slippage between the secondary spur gear 18 and the ratchet 17. Hence the faster the paddle 14 is rotated the greater the reduction in clamping force and the faster the descent of the paddle.

The connection between the primary shaft 12 and gear shaft 13 may be made by other means in place of the primary and secondary spur gears 15,18, for example by means of a chain. In addition, if desired to ease the load on an operator of the mechanism 10, additional gears may be incorporated.

It will be appreciated that if desired, instead of providing the brake on gear shaft 13, a brake may instead be provided on primary shaft 12. In this case a nut may be threaded onto the primary shaft 12 which moves along the shaft to engage a stop, to prevent free fall of the paddle.

Many other modifications to the mechanism described may be made without departing from the scope of the invention.

The features disclosed in the foregoing description the following claims or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims (7)

1. A mechanism for raising and lowering a paddle in a sluice, weir or lock-gate comprising operating means to move the paddle between fully raised and fully lowered positions, and means to prevent the free-fall of the paddle under gravity to its fully lowered position.

2. A mechanism according to claim 1 wherein the operating means comprises a manually operable member, and a transmission to transmit drive to the paddle, the transmission comprising a shaft driven by the manually operable member, the means which prevent free-fall of the paddle comprising a brake which operates on the shaft and which, whilst the operating means is operated to lower the paddle, is permitted to slip, allowing the paddle to lower under gravity in a controlled fashion.

3. A mechanism according to claim 2 wherein the transmission which transmits drive to the paddle during raising of the paddle, is de-coupled during lowering of the paddle.

4. A mechanism according to claim 2 or claim 3 wherein the shaft carries a gear which meshes with a drive element fixed to the paddle.

5. A mechanism according to claim 2 or claim 3 or claim 4 wherein the brake comprises a ratchet and pawl, the pawl being engaged with the ratchet to prevent rotation of the ratchet in a first direction, and means to clamp the ratchet to the shaft whilst the paddle is being raised or is in a raised condition and to release the ratchet such that the shaft may rotate with respect to the ratchet whilst the operating means is operated to lower the paddle.

6. A mechanism according to claim 5 wherein the means to clamp the ratchet to the shaft comprises a shoulder on the shaft, a threaded portion of the shaft carrying the ratchet and a gear driven by the manually operable member, arranged such that when the operating means is operated to raise the paddle, the gear and ratchet are moved along the threaded portion of the shaft and clamped against the shoulder such that the pawl prevents the shaft rotating in the first direction and when the operating means is operated to lower the paddle, the gear and ratchet move along the threaded portion of the shaft away from the shoulder permitting the shaft to rotate in the first direction and the paddle to lower.

7. A mechanism substantially as hereinbefore described with reference to and as shown in the accompanying drawing.

7. A mechanism according to claim 2 or claim 3 wherein the transmission includes a further shaft driven from the first mentioned shaft, which further shaft carries a gear which meshes with a drive element fixed to the paddle.

8. A mechanism substantially as hereinbefore described with reference to and as shown in the accompanying drawing.

9. Any novel feature or novel combination of features as herein defined and/or shown in the accompanying drawing.

Amendments to the claims have been filed as follows 1. A mechanism for raising and lowering a paddle in a sluice, weir or lock-gate comprising operating means to move the paddle between fully raised and fully lowered positions, comprising a manually operable member, and a transmission to transmit drive to the paddle, the transmission comprising a shaft driven by the manually operable member, and means to prevent the free-fall of the paddle under gravity to its fully lowered position, comprising a brake which operates on the shaft and which, whilst the operating means is operated to lower the paddle, is permitted to slip, allowing the paddle to lower under gravity in a controlled fashion.

2. A mechanism according to claim 1 wherein the transmission which transmits drive to the paddle during raising of the paddle, is de-coupled during lowering of the paddle.

3. A mechanism according to claim 1 or claim 2 wherein the shaft carries a gear which meshes with a drive element fixed to the paddle.

4. A mechanism according to claim 1 or claim 1 or claim 3 wherein the brake comprises a ratchet and pawl, the pawl being engaged with the ratchet to prevent rotation of the ratchet in a first direction, and means to clamp the ratchet to the shaft whilst the paddle is being raised or is in a raised condition and to release the ratchet such that the shaft may rotate with respect to the ratchet whilst the operating means is operated to lower the paddle.

5. A mechanism according to claim 4 wherein the means to clamp the ratchet to the shaft comprises a shoulder on the shaft, a threaded portion of the shaft carrying the ratchet and a gear driven by the manually operable member, arranged such that when the operating means is operated to raise the paddle, the gear and ratchet are moved along the threaded portion of the shaft and clamped against the shoulder such that the pawl prevents the shaft rotating in the first direction and when the operating means is operated to lower the paddle, the gear and ratchet move along the threaded portion of the shaft away from the shoulder permitting the shaft to rotate in the first direction and the paddle to lower.

6. A mechanism according to claim 1 or claim 2 wherein the transmission includes a further shaft driven from the first mentioned shaft, which further shaft carries a gear which meshes with a drive element fixed to the paddle.