GB2066771A - Derrick - Google Patents

Abstract

A derrick (20) has an upstanding support frame (21), a derrick lifting arm (23) and a lifting line (33). The lifting arm is pivoted about an axis defined on the support frame by a horizontal pivot (22) and is angularly movable between extremities disposed one on each side of a vertical plane passing through the axis. The arm (23) has an extension 31 parallel to the axis and is loaded towards its extreme positions by a spring (29). The lifting line (33) passes over a pulley (30) at the end of extension (31), a pulley (32) at the angle when extension (31) meets main part (34) of the arm (23), between a pair of pulleys (35, 36) on the main part (34) and between a pair of pulleys (37, 38) on the frame (21) to a hoisting position. The derrick (20) may be mounted on a trailer (not shown) and used to lift a boat (not shown) on to the trailer, the boat being first lifted to the head of the arm (23), continued hoisting moving the arm (23) about the pivot (22). <IMAGE>

Description

SPECIFICATION Derrick This invention relates to an improved derrick and to a vehicle such as a trailer including such a derrick.

According to the present invention there is provided a derrick comprising a support member, a derrick lifting arm angularly movable about a pivot on the support member the axis of which, in use, is substantially horizontal, and a lifting line for passing between the derrick lifting arm and the support member to a hoist position, the derrick lifting arm being angularly movable between extremities disposed one on each side of a vertical axis passing through said pivot. Suitably the derrick lifting arm according to claim 1 wherein the derrick lifting arm is pivoted at one end and includes first bearing means at the other end remote from its point of pivot and, bearing means intermediate its ends, in use the lifting line passing from the load to be lifted, over the first bearing means, the intermediate bearing means and a bearing means on the support member to the hoist position.

Preferably the intermediate bearing means is positioned in the same plane and approximately at the same distance from the pivot as the bearing means on the support member.

The invention also includes a vehicle such as a trailer comprising a vehicle body and a derrick mounted on the vehicle body, the derrick comprising a vehicle such as a trailer comprising a vehicle body and a derrick mounted on the vehicle body, the derrick comprising an upstanding support member including a substantially horizontal pivot, a derrick lifting arm angularly movable about the horizontal pivot, and a lifting line for passing between the derrick lifting arm and the support member to a hoist position, the derrick lifting arm being angularly movable between extremities disposed one on each side of a vertical axis passing through said pivot.

This invention will now be described by way of example with reference to the accompanying drawings in which figure 1 illustrates diagrammatically a first embodiment in which a derrick in accordance with the invention is mounted on a trailer. Figure 2 is a diagrammatic front elevation of a second, preferred, embodiment; figure 3 is a side elevation in the direction of arrow A in figure 2; figure 4 is a simplified diagrammatic perspective view of the second embodiment at a first extremity of angular movement with the loading means omitted, and figure 5 is a simplified diagrammatic perspective view of the second embodiment at a second extremity of angular movement with the loading means omitted.In the drawing of the first embodiment a trailer 1 , for a boat, has a transverse frame 2, supporting transport wheels 3, and a longitudinal support bar 4 suitably having a hitch connection 5 at its free end to facilitate towing.

Mounted to one side of the transverse frame 2 is a derrick 6 comprising an upstanding frame 7 having side members 8 and a derrick lifting arm 9.

The derrick lifting arm 9 is pivoted at 10 at the junction between the upstanding frame 7 and the transverse frame 2 and has an angled portion 11 at its free end. The derrick lifting arm 9 is able to pivot in a fixed plane parallel to the plane of frame 7. A pulley A is mounted on the frame 7 and a pulley B is mounted intermediate the ends of the lifting arm 9 suitably nearer the angled portion 11 to give the necessary mechanical advantage for lifting as will be explained: the axis of the pulleys A and B being substantially horizontal. A lifting line 12 passes from a swivel pulley 13 at the lifting head F to a pulley 14 at the angled portion 11, to pulley B, then to pulley A and then to the effort point designated E.

In figure 1 the derrick lifting arm 9 is shown in its inner angular position. However, when lifting begins, the arm 9 is at the other extremity so as to extend outwardly from the rear of the trailer. The pulley arrangement is such that as the article being lifted reaches the lifting head F the pulley B will be pulled towards the pulley A thus moving the derrick lifting arm 9 to the perpendicular about its pivot 10. The pulleys A and B are suitably in the same plane but are arranged to pass one under the other so that the derrick lifting arm 9 can achieve a perpendicular disposition and swing past the perpendicular to the position shown so as to stow a lifted boat onto the trailer 1.

Although figure 1 of the present invention has been particularly described with reference to a derrick on a boat trailer it will be understood that the derrick of the present invention may be mounted wherever required e.g.: on a lifting vehicle, high-sided rigid bodied vehicle, or ship and therefore in the second embodiment no supporting vehicle is shown.

In the embodiment of figures 2 to 5 a derrick 20 comprises an A-shaped support frame 21 which may be fixedly mounted on any suitable vehicle or at a dock-side for example (not shown).

Pivoted to the frame 21, at the junction 22 between one of the side members of the frame 21 and its base, is an L-shaped derrick lifting arm 23.

The derrick lifting arm 23 is able to move in a fixed plane parallel to the plane of the frame 21 between angular extremities represented by the full and dotted lines in figure 2 and as shown diagrammatically in figures 4 and 5.

Mounted between the derrick lifting arm 23 and the frame 21 is a telescopic loading means 24 which comprises a first, outer part 25 pivoted to the frame on a pin 26 and a second, inner part 27 pivoted to the lifting arm 23 on a pin 28. The part 27 is slidably received within the part 25 in order to accommodate movement of the lifting arm and loading is provided by a coil spring 29 disposed within the outer part 25.

In order to provide the desired mechanical advantage for lifting, the pulley arrangement of the second embodiment comprises a first pulley 30, at the head of the lifting arm 23, which is mounted for swivelling movement about the axis of the angled end 31 of the lifting arm 23 so that during lifting the plane of the pulley 30 is always substantially vertical. A second pulley 32 is mounted at the angle in the lifting arm 23 in order to direct the lifting line 33 into alignment with the main part 34 of the lifting arm. Third and fourth pulleys 35, 36 are mounted intermediate the ends of the main part 34 of lifting arm and two further pulleys 37, 38 are mounted as close together as possible at the top of the frame 21.

In use, when the lifting arm 23 is outboard, as shown in figure 2, the lifting line 33 passes from the first and second pulleys 30, 32 between the pulleys 35, 36 and then between the pulleys 37, 38 to a hoist position E. The pulleys 35, 36 and 37,38 are provided in pairs so that, as the lifting arm 23 passes through the perpendicular during lifting, the lifting line 33 passes from one pulley to the other in each of the pairs.

On lifting a boat, for example (not shown), the boat is first lifted to the head of the lifting arm 23.

Once in this position continued hoisting on the line 33 causes the lifting arm 23 to move about its pivot 22 so as to draw the boat inboard when the lifting arm 23 reaches its final position indicated by the dotted lines in figure 2. The loading means 24 is arranged such that, as the lifting arm 23 moves towards the perpendicular, the coil spring 29 is compressed increasing the loading on the lifting arm 23 thereby counterbalancing the weight of the boat as the load of the derrick lifting arm 23 decreases towards top dead centre. The loading of the coil spring 29 also aids in forcing the derrick lifting arm 23 beyond top dead centre into its inboard position shown in dotted lines in figure 2.

Claims (10)

CLAiMS

1. A derrick comprising a support member, a derrick lifting arm angularly movable about a pivot on the support member the axis of which, in use, is substantially horizontal, and a lifting line for passing between the derrick lifting arm and the support member to a hoist position, the derrick lifting arm being angularly movable between extremities disposed one on each side of a vertical axis passing through said pivot.

2. A derrick according to claim 1 wherein the derrick lifting arm is pivoted at one end and includes, first bearing means at the other end remote from its point of pivot and a first pair of bearing means intermediate its ends, in use the lifting line passing from the load to be lifted, over the first bearing means, between the first pair of bearing means, over a second pair of bearing means on the support member to the hoist position.

3. A derrick according to claim 2 wherein the derrick lifting arm is angled at its said other end and includes a second bearing means at said angle over which the lifting line passes in use.

4. A derrick according to claim 2 or 3 wherein the bearing means comprise pulleys.

5. A derrick according to any one of the preceding claims comprising a loading means between the support member and the lifting arm.

6. A derrick according to claim 5 wherein said loading means comprises a first part telescopically received in a second part, and a coil spring within said second part loaded by compression thereof when the first part is telescoped into the second part, one of the two parts being pivoted to the support member and the other being pivoted to the derrick lifting arm.

7. A derrick according to claim 1 wherein the derrick lifting arm is pivoted at one end and includes first bearing means at the other end remote from its point of pivot and, bearing means intermediate its ends, in use the lifting line passing from the load to be lifted, over the first bearing means, the intermediate bearing means and a bearing means on the support member to the hoist position.

8. A derrick according to claim 2 or 7 wherein the first bearing means is mounted for swivelling movement about the end of the lifting arm.

9. A vehicle such as a trailer comprising a vehicle body and a derrick mounted on the vehicle body, the derrick comprising an upstanding support member including a substantially horizontal pivot, a derrick lifting arm angularly movable about the horizontal pivot, and a lifting line for passing between the derrick lifting arm and the support member to a hoist position, the derrick lifting arm being angularly movable between extremities disposed are on each side of a vertical axis passing through said pivot.

10. A derrick substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.