GB2132158A

GB2132158A - Chain heaving device

Info

Publication number: GB2132158A
Application number: GB08333140A
Authority: GB
Inventors: Aton Brohl
Original assignee: Broehl Maschf GmbH
Current assignee: Broehl Maschf GmbH
Priority date: 1982-12-27
Filing date: 1983-12-12
Publication date: 1984-07-04
Also published as: NL8303243A; DE3248207A1; GB8333140D0; NO833708L; GB2132158B

Abstract

A heaving device is described for hauling-in and slackening-off chains with round steel links, suitable particularly for tautening and making fast anchor chains and the like on ocean-going ships, off-shore oil-drilling platforms and the like. The device comprises a stationary chain-stop (2) which drives a mobile chain-stop (3) hydraulically, so that the latter reciprocates, rolling back and forth on a track. The two chain- stops (2, 3) engage alternately with the chain (4), hauling the chain in or slackening it off, intermittently, step by step. The two chain-stops (2, 3) are mounted on a common base-frame (1) to form a self-contained unit which can be fixed in place at any desired location on the structure of the ship or platform or the like. <IMAGE>

Description

SPECIFICATION Chain heaving device The invention relates to a heaving device for chains with round-steel links suitable particularly for tautening and making fast anchor chains and the like. In particular the invention relates to a device for hauling-in and slackening-off chains with round-steel links, particularly for tautening and making fast anchor chains or the like, comprising a stationary chain-stop equipped with two chain-guiding tracks extending parallel to each other in the longitudinal direction of the chain, for guiding the horizontal chain-links, the tracks having between them a channel for guiding the verticl chain links, the heaving device also having, above the chain, a pawl pivoted on a horizontal axle for locking the chain in place when it is under tension.

Devices of this kind are used mainly on ocean-going ships and off-shore oil-drilling platforms for tautening and securing the anchor chains, which can in some cases be several hundred metres long. They are also used quite generally for securing floating marine gear of many different kinds by means of anchor chains.

Hitherto there have been used for this purpose very heavily constructed rotary capstans backed by mechanical chain-stops, as described, for example, in the German Patent Specifications 25 52 057 and 26 09 569.

The chain is hauled-in or slackened-off by the capstan and locked in place by the chain stops.

A capstan with sufficient hauling power is very costly to construct, and the hauling power available, i.e. the tension which can be applied to the chain, is limited and is often insufficient for certain special requirements in oil-drilling operations.

The intention in the present invention is to provide a heaving device of the kind described at the outset of this Specification, for chains with round-steel links, with a chainshop, the new device being comparatively simple in construction and yet reliable in operation. The new device does not use a rotary capstan and is capable of handling even the highest loads.

According to the invention there is provided a chain heaving device for hauling-in and slackening-off chains with round-steel links, particularly for tautening and making fast anchor chains or the like, comprising a stationary chain-stop equipped with two chain-guiding tracks extending parallel to each other in the longitudinal direction of the chain, for guiding the horizontal chain links, the tracks having between them a channel for guiding the vertical chain links, the heaving device also having, above the chain, a pawl pivoted on a horizontal axle for locking the chain in place when it is under tension, characterised in that pivoted to the stationary chain-stop there is a hydraulic driving cylinder for thrusting a mobile chain-stop forwards by the stroke of the driving cylinder, against the pull applied by the anchor to the chain, and for returning the mobile chain-stop to its first position, the hauling-in of the chain being done intermittently, step by step, by alternately engaging and disengaging selectively the one or the other of the two chain-stops, the chain being slackened-off by reversing the sequence of operations.

The invention has the advantage, in the first place, that no rotary capstan is required, the two chain-stops, of which the one is stationary, the other mobile, between them haulingin the chain, or slackening it off, intermittently, step by step, the chain being locked securely in place between the steps of movement. The mobile chain-stop is driven hydraulically, as, with advantage, are also the pawls which lock the chain in place on each chainstop. The operation of the heaving device gives the operator very sensitive control of the tension applied to the chain and of the movements during hauling-in and slackening-off of the chain allowing him to adjust the movements of parts accurately to suit the existing requirements.

An excellent driving action for the mobile chain-stop is obtained as described in Claim 2, particularly with the help of the arrangements specified in Claim 3, which give the mobile chain-stop an easy movement free from tilting movements. The easy driving of the mobile chain-stop is still further improved as described in Claim 4.

A particularly stable and compact construction, for transportation and installation as a self-contained unit, is described in Claim 5.

Accurate and reliable engagement, and locking of the pawls, is ensured as described in Claims 6 to 12.

Further details and advantages of the invention can be derived from the following more detailed description based on the example represented diagramatically in the drawing in which: Figures 1 and 2 represent diagramatically the method of functioning of the heaving device, which is shown in two different operating positions.

Figure 3 is a diagramatic side-view of the device.

Figure 4 is a partly sectioned plan-view of the device of Fig. 3.

Figure 5 is a partly sectioned side-view of a detail drawn to a larger scale, the section taken in the plane V-V of Fig. 4.

Figure 6 is a transverse section taken in the plane VI-VI of Fig. 5.

Figure 7 is a longitudinal section of a detail taken in the plane VII-VII of Fig. 6.

Figure 8 is a horizontal section of a detail, taken in the plane VIII-VIII of Fig. 7.

The heaving device comprises a base-frame 1 on which is fixed rigidly a stationary chainstop 2. This drives hydraulically a mobile chain-stop 3 so that the latter moves back and forth in hauling-in or slackening-off the anchor chain 4. The pull applied by the anchor to the chain 4, i.e. the anchor load, is exerted towards the left in Fig. 1, as is also indicated at 1 8 in Figs. 7 and 8. In hauling-in the anchor, the anchor chain 4 therefore moves towards the right in Fig. 1. The hauling-in of the anchor chain 4 takes place intermittently, step by step, the two anchor-stops 2 and 3 engaging with the anchor chain 4 alternately.

As shown best in Figs. 3 and 4, the baseframe 1 is a welded box-structure suitable for welding in place at a suitable location, i.e. at any desired located, on the deck or frame of an ocean-going ship or an off-shore oil-drilling platform or the like. The base-frame 1 has lateral support rails 5 on which runs, with the help of rollers 1 2 (Fig. 1), the mobile chainstop 3, guided laterally by guide-rails 6. The mobile chain-stop 3 is driven to roll back and forth by one or more hydraulic driving cylinders 7 (Fig. 4), each pivoted at one end to the stationary chain-stop 2, and at the other end to the mobile chain-stop 3. The pull of the anchor chain 4 is transmitted from the chainstops 2, 3 through the base-frame 1 to the structure of the ship or platform. Furthermore, the base-frame 1 conveniently houses all the parts of the heaving device.For further convenience the free end 4a (Fig. 3) of the chain 4 can be secured with the help of a pin 8.

Each chain-stop 2, 3 houses a parallel pair of longitudinal chain-guiding tracks 9 on which slide the horizontal chain links 4b (Fig.

7), and between each pair of chain-guiding tracks 9 there is a chain-guiding channel 10 (Figs. 4 and 8) for the vertical links 4c. It will also be observed that the upper surfaces of each pair of chain-guiding tracks 9 are interrupted by recesses 17, as shown in Figs. 7 and 8. To lock the chain in place each chainstop 2, 3 has a pair of parallel pivoted pawl arms 11 (Fig. 1) whose pawl-blocks ?la engage in the recesses 1 7.

In this example the stationary chain-stop 2 drives the mobile chain-stop 3 by means of two parallel hydraulic driving cylinders 7, one on each side of the chain 4. Between driving strokes the stationary chain-stop 2, fixed firmly to the base-frame 1, holds the chain 4 securely in place with the help of its pawlblocks 11 a, the stationary chain-stop 2 acting as a back-stop for the chain 4.

The two chain-stops 2 and 3 are of essentially similar construction. The mobile chainstop 3 is pivoted to the other ends of the parallel driving cylinders 7 and moves back and forth on the rollers 12, which roll on the support rails 5. To ensure stability of the mobile chain-stop 3, the pivot pin 13 (Fig. 3) of the stationary chain-stop 2, for each driving cylinder 7, is situated at a higher level than the pivot pin 14 of the mobile chain-stop 3.

This ensures that chain tension thrusts the mobile chain-stop 3 firmly down on the support rails 5.

When the heaving device is in operation, either hauling-in the chain or slackening it off, the horizontal chain links 4b are alternately blocked and released by the pawl blocks 11 a of the two chain-stops 2, 3, the pawl-blocks 11 a being raised and lowered by hydraulic pawl-cylinders 1 5 (Fig. 5). In the event of hydraulic failure the pawl-blocks 11 a fall automatically under gravity into engagement between the horizontal chain-links 4b, locking the chain 4 in place.

To prevent tilting movements from acting on the mobile chain-stop 3 on the base-frame 1, the pivot pin 14 (Fig. 3) on which each hydraulic cylinder 7 pivots on the mobile chain-stop 3 is situated behind the pawl-arm 11, in the direction of cylinder thrust, when the pawl-arm 11 is in its locking position. And the mobile chain-stop 3 is guided laterally along the base-frame 1 by lateral guide-rollers 1 6b rotating on vertical axes 16a.

As shown in Figs. 5 to 8, the two pivoted pawl-arms 11 of each chain-stop 2, 3 engage with the chain 4 by means of a pair of pawlblocks 11 a which engage beind the horizontal chain link 4b on either side of the vertical chain link 4c, the lower end of the chain-block 11 a penetrating downwards into the recess 1 7 of the chain-guiding track 9.Under these circumstances the back-surface of each chainblock 11 a is thrust backwards by the pull of the chain 4, acting in the direction of the arrow 18 in Figs. 7 and 8, to rest in contact with the back-surface 19 of the recess 17, so that the pull of the chain 4 is taken by this back-surface 1 9. In a preferred version of the invention each chain-block 11 a is constructed in such a way that it penetrates substantially vertically downwards between the horizontal chain links 4b into the recess 17, allowing the chain-block 11 a to be lifted out of engagement vertically, even when the chain 4 is under load. To ensure that the two chainstops 2 and 3 take up the chain links evenly, each pawl-arm 11 rotates loosely, i.e. with a certain amount of free play, on its pawl-axle 20. Clamped to the pawl-axle 20 is a forked driver-arm 21 (Fig. 7). To swing the pawl-arm 11 into and out of engagement with the chain 4, a driver-pin 22 is fixed to the pawl-arm 11, the driver-pin 22 working loosely, i.e. with some free play, in the fork. The pawl-axle 20 is driven to swing back and forth by the piston 24 (Fig. 5) of a hydraulic actuating cylinder 15, the piston 24 acting on a lever 23 fixed to the pawl-axle 20. The actuating pin of the lever 23 works in an axial slot 25 in the head of the piston 24, the slot 25 giving the pawl-axle 20 a certain amount of free play rotationally.

Fixed to the pawl-axle 20 there is also a switch-plate with electric contact tangs 26 for contacting electric contacts 27 when the pawl-axle 20 swings back and forth. The contacts 27 are mounted, adjustable in position, on a web 27a or the like of the baseframe 1.

Extending forwards ( Fig. 1) from the stationary chain-stop 2 there is an extensionframe 28. When the mobile dhain-stop 3 travels backwards, towards the left in Fig. 1, it comes to rest firmly up against the extension-frame 28, so tha the two chain-stops 2, 3 together form as secure locking structure for taking the enduring pull of the chain.

As shown in Figs. 3 and 4, the heaving device has, fixed to one side of the base-frame 1, a power unit 30 complete with its control system 30. The power unit can comprise a Diesel engine, making the heaving device entirely independent of the shipboard electric power system. Or the power unit can comprise an electric motor taking current from the shipboard electric power system. Only one man is required for operating the heaving device, which he does directly and hydraulically. When hauling-in the chain the operator can read off from an instrument the hydraulic pressure acting on the driving cylinders 7 and the tension on the chain.

The operation of hauling-in a chain follows the sequence: 1. The mobile chain-stop 3 is locked in place.

2. With its pawl-block engaged, the mobile chain-stop 3 takes the load of the chain.

3. The pawl-block of the stationary chainstop 2 is disengaged.

4. The mobile chain-stop 3 is driven forwards, towards the right in Fig. 1, by the length of stroke of the hydraulic driving cylinders 7.

5. The pawl-block of the stationary chainstop 2 is engaged.

6. The chain load is taken by the stationary chain-stop 2.

7. The pawl-block of the mobile chain-stop 3 is disengaged.

8. The mobile chain-stop 3 is retracted to its position of rest, up against the extensionframe 28.

9. The cycle is repeated.

To slacken-off the chain, the sequence of operations is reversed.

The entire control system is designed to ensure that whenever operations are interrupted, the heaving device stays immobile with the parts stationary In their existing positions. It should be observed that the chain 4 is at no time stressed by any squeezing or clamping action. Chain load is always taken positively by the direct supporting action of the chain-stops 2, 3. The heaving device takes all the conventional anchor chains.

Claims

1. A chain heaving device for hauling-in and slackening-off chains with round-steel links, particularly for tautening and making fast anchor chains or the like, comprising a stationary chain-stop equipped with two chainguiding tracks extending parallel to each other in the longitudinal direction of the chain, for guiding the horizontal chain-links, the tracks having between them a channel for guiding the vertical chain links, the heaving device also having, above the chain, a pawl pivoted on a horizontal axle for locking the chain in place when it is under tension, characterised in that pivoted to the stationary chain-stop (2) there is a hydraulic driving cylinder (7) for thrusting a mobile chain-stop (3) forwards by the stroke of the driving cylinder (7), against the pull applied by the anchor to the chain (4), and for returning the mobile chain-stop (3) to its first position, the hauling-in of the chain (4) being done intermittently, step by step, by alternately engaging and disengaging selectively the one or the other of the two chain-stops (2, 3), the chain (4) being slackened-off by reversing the sequence of operations.

2. A chain heaving device as claimed in Claim 1, characterised in that the stationary chain-stop (2) drives the mobile chain-stop (3) by means of hydraulic cylinders (7) aranged longitudinally and parallel to each other on either side of the chain (4).

3. A chain heaving device as claimed in Claims 1 and 2, characterised in that the pivot-points (1 3) where the two hydraulic cylinders (7) are pivoted on the stationary chainstop (2) are situated at a higher level than the pivot-points (14) where the two cylinders (7) are pivoted on the mobile chain-stop (3) firmly down on its support rails (5).

4. A chain heaving device as claimed in Claims 1 to 3, characterised in that the pivotpoints of the hydraulic cylinders (7) on the mobile chain-stop (3) are situated behind the pawls (11, 11 a) in the direction of thrust of the hydraulic cylinders (7).

5. A chain heaving device as claimed in Claims 1 to 4, characterised in that the two chain-stops (2) and (3) are both mounted on the same base-frame (1), the stationary chainstop (2) being fixed to the base-frame (1), the mobile chain-stop being arranged to travel back and forth along the base-frame (1) on support-rails (5) and with the help of lateral guide-rails (6).

6. A chain heaving device as claimed in Claims 1 to 5, characterisd in that the mobile chain-stop (3) is guided laterally along the base-frame (1) by lateral rollers (16b) which rotate on vertical axes (16a).

7. A chain heaving device as claimed in Claims 1 to 6, characterised in that each chain-stop (2, 3) has a pair of pawls (11, 1 la), each comprising a pawl-arm (11) and a pawl-block (ill), the two pawl-blocks (11a) of each pair being situated transversely next to each other but leaving a gap between them to give room for the vertical link (4c) of the chain (4); each pawl-block (11a) being long enough to penetrate, when the pawl (11, 11 a) is engaged with the chain (4), downwards into a recess (17) in the chain-guiding track (9); the back-surface of the pawl-block (ill) resting in contact with a substantially vertical back-stop surface (19) of the recess (17), so that chain tension (18) pulls the pawl-block (11 a) backwards in firm contact with the back-stop surface (19).

8. A chain heaving device as claimed in one of the above claims, characterised in that the pawl-arms (11) swing on pivots, each pawl-block (11 a) being constructed so that, in the chain-blocking process, the pawl-block (11 a) penetrates downwards substantially vertically between neighbouring horizontal chain links (4b) into the recess (17) of the chainguiding track (9).

9. A chain heaving device as claimed in one of the above claims, characterised in that each pair of pawl-arms (11) of each chainblock (2, 3) is pivoted loosely, leaving some free play in the bearing, on its pawl-axle (20); the pawl-arm (11) being swung back and forth by means of a forked arm (21) clamped firmly to the pawl-axle (20), the forked arm (21) driving the pawl-arm (11), to swing back and forth by means of a driving pin (22) fixed to the pawl-arm (11) and working loosely, with free play, in the fork of the arm (21).

10. A chain heaving device as claimed in one or more of the above claims, characterised in that the pawl-axle (20) is driven rotationally by the piston (24) of a hydraulic cylinder (15), the piston (24) acting on a radial lever (23) fixed to the pawl-axle (20), the radial lever (23) nevertheless having some freedom of movement in the longitudinal direction of the cylinder (15).

11. A chain heaving device as claimed in the above claims, characterised in that the pistion (24) of the hydraulic cylinder (15) has a longitudinal slot (25) in which works the driving pin of the radial lever (23) fixed to the pawl-axle (20).

1 2. A chain heaving device as claimed in one or more of the above claims, characterised in that the stationary chain-stop (2) has, projecting forwards from it, an extensionframe (28) which acts as a back-stop for the mobile chain-stop (3) when the latter is in its fully-backwards position.

1 3. A chain heaving device substantially as hereinbefore described with reference to the accompanying drawings.