GB2137723A - Release shackle - Google Patents

Abstract

The invention relates to a release shackle comprising a body (1) having a slot (2), and a pin (3) arranged across the slot (2). The pin (3) is movable from a position bridging the slot (2) to a position free of the slot by ratchet means (4), preferably a ratchet wheel 5 and toothed strap (8). The invention prevents the pin from being accidentally released. <IMAGE>

Description

SPECIFICATION Release shackle The present invention relates to a release shackle, in particular a release shackle for lifting and releasing steel sheet piles. Such release shackles are commonly known as ground release shackles or quick release shackles.

A known release shackle comprises a body having a slot to fit the edge of a sheet pile, and a pin which traverses the slot and passes through a hole in the pile to hold the pile. The pin is kept in place by a strong spring. After the pile has been lifted and placed in position, a rope connected to the pin is pulled with a sufficient force to overcome the spring force and so release the pile.

This known release shackle has great disadvantages. There is a tendency for the rope connected to the pin to become entangled with the other lifting tackle. In this situation the pin might be accidently retracted and the pile can be dropped. This is obviously very dangerous and can lead to serious injury and even fatalities.

Another disadvantage is that the pin can become jammed in the hole and so be very difficult to remove from a remote position on the ground.

An object of the present invention is to provide a release shackle which overcomes or at least mitigates the disadvantages of the known release shackles.

According to the invention there is provided a release shackle comprising a body, the body having a slot, and a pin arranged transversely to the slot, and wherein the pin can be moved from a position bridging the slot to a position clear bf the slot by means of a ratchet mechanism.

Preferably the pin comprising an extension which is visible outside the body when the pin is clear of the slot.

Preferably, the ratchet mechanism comprises a ratchet wheel.

An embodiment of the invention is described in detail below, by example only, with reference to the accompanying drawings, wherein: Fig. 1 is a side view of a release shackle according to the invention; Fig. 2 is a perspective view of the shackle of Fig. 1; Figs. 3a, 3b and 3c comprise an exploded view of the arrangement of the pin and ratchet mechanism of the release shackle; and Figs. 4a and 4b are further views showing the ratchet mechanism.

As shown in Figs. 1 and 2 the release shackle comprises a body 1 which has a slot 2, and a pin 3 arranged transversely to the slot. The pin 3 is associated with a ratchet mechanism 4.

The ratchet mechanism 4 comprises a ratchet wheel 5 and is housed in a recess 6 in the body 1.

The pin 3 is terminated on the outside of the body 1 by a nut 7. The pin extends through a bore in the body 1 on either side of slot 2, and through the recess 6 and can be moved by the ratchet wheel 5 from a position bridging the slot 2 to a position wherein the slot 2 is open. The ratchet wheel is operated by means of an indented strap 8 which is threaded through the recess 6 and partly surrounds and engages the wheel 5. An indicator bar 9 is arranged on the end of the pin 3 remote from the slot 2 and extends through the slot 7 when the pin is retracted.

The pin and ratchet mechanism are illustrated more clearly in Figs. 3a, 3b and 3c. Fig. 3a shows the pin 3. The pin 3 comprises a main threaded portion 10 and the indicator bar 8 which is narrower than the portion 10. A longitudinal slot 11 is formed along the surface of the threaded portion 1 0. The ratchet wheel is illustrated in Fig.

3b, and Fig. 3c shows the nut 7. The nut 7 comprises a head 12 and a narrower body portion 13. A threaded bore 14 extends through the portion 13 and into the head 12. The head 11 also has a bore 15 for the bar 9. The wheel 5 has a central bore 1 6 of a similar diameter to that of the body portion 13 of the nut 7.

The pin and ratchet mechanism are assembled in the body of the release shackle by placing the ratchet wheel 5 and belt 8 in the recess 6, sliding the pin 3 across the recess 6 and then threading the nut 7 onto the pin 3 from the outside of the body 1. The body portion 13 of the nut 7 fits in the bore 1 5 of the wheel 5 and is locked with the wheel by means, for example, of screws.

Fig. 4a shows another view of the ratchet wheel 5, showing the central bore 1 6 and the ratchet teeth 1 7. Fig. 4b show the ratchet spring and pawl 1 8 which fits within the recess 6 of the body of the release shackle to engage with the wheel 5. The foot of the pawl 18 can be seen in Fig. 2.

The ratchet wheel 5 is rotated by means of the toothed strap 8 which in use has a rope attached to each end. Pulling on one rope will draw the strap through the recess in one direction, pulling on the other rope will draw the strap in the other direction. In one direction of strap movement the teeth 1 6 of the wheel 5 engage the indentations of the strap 8 and the pawl 1 8 slips over the teeth so the wheel rotates. In the other direction of strap movement the pawl catches in the teeth 1 7 preventing the wheel from rotating and the strap 8 slips around the wheel. When the wheel 5 rotates so does the nut 7 which is fixed to it. The rotation of the threaded portion 13 of the nut 7 engaging with the correspondingly threaded portion 10 of the pin 3 causes the pin to move away from the slot 2.The pin 3 is prevented from rotating by a key extending through the body 1 between the slot 2 and the recess 6 which engages in the slot 11 of the pin.

In use, the release shackle of the invention is attached to the end of a steel sheet pile by slotting the body onto the pile. The pawl 1 8 is then released and the pin 3 made to pass through a hole in the pile by turning the nut 7. As previously mentioned, a rope is attached to each end of the toothed strap 8. The pile is then lifted by means of the release shackle and is guided into the correct position. To release the shackle, one of the ropes is pulled to draw the full length of the strap 8 across the ratchet wheel 5 to rotate it. This causes the nut 7 to rotate and thus the pin to partially retract. The strap is then pulled by the other rope back across the ratchet wheel but, as explained above, this does not cause the nut to rotate and so the pin is not moved back into the body.The strap is then pulled back across the ratchet wheel with the first rope to further retract the pin. The process is repeated until the pin is clear of the slot and so the shackle is released. The pin and ratchet mechanism might be designed such that five or six strokes of the strap were necessary to fully release the pin. As the pin is being retracted, the indicator bar 9 extends from the nut to a greater and greater extent so that is possible to see from the ground the position of the pin.

The invention has the great advantage that the release procedure for the shackle could not be instigated by accident. On the other hand, the force needed to release the pin is not too great. In the described embodiment, the numerous strokes of the strap needed to retract the pin mean that even if the release ropes become snagged this could not cause the strap to be pulled back and forth sufficiently to let the pile drop accidentally.

Further the indicator bar which extends clearly from the body of the release shackle as the pin is being retracted means that the safe clamping of the pile can be checked from the ground.

Alternatively to the described arrangement using a ratchet mechanism, according to another aspect of the invention there is provided a release shackle comprising a body, the body having a slot, and a pin arranged transversely to the slot, and wherein the pin is threaded and can be moved from a position bridging the slot to a position clear of the slot by means of rotational movement of the pin or of a threaded member with which the pin is engaged.

Claims (6)

1. A release shackle comprising a body, the body having a slot; a pin arranged transversely of the slot; and ratchet means for moving the pin from a position bridging the slot to a position clear of the slot.

2. A release shackle as claimed in claim 1, wherein the pin comprises an extension which is visible outside the body when the pin is clear of the slot.

3. A release shackle as claimed in claim 1 or 2, wherein the ratchet means comprises a ratchet wheel and pawl.

4. A release shackle as claimed in claim 3, wherein the pin has a screw thread which engages with a corresponding screw thread associated with the ratchet wheel, and wherein the pin is keyed with the body whereby rotation of the ratchet wheel moves the pin across the slot.

5. A release shackle as claimed in claim 3 or 4, and including a toothed strap for rotating the ratchet wheel.

6. A release shackle substantially as herein described and as illustrated in the accompanying drawings.