GB2119748A

GB2119748A - Pipe lifting devices

Info

Publication number: GB2119748A
Application number: GB08312681A
Authority: GB
Inventors: David John Mccormick
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-05-07
Filing date: 1983-05-09
Publication date: 1983-11-23
Also published as: GB8312681D0; GB2119748B

Abstract

A pipe lifting device, especially for lifting concrete pipe sections, comprises a pin having a shaft portion (10) which fits through a hole in the section of pipe, and a gravity-operated latch, such as a toggle (22), which operates automatically when the pin is inserted through the hole in the pipe section and which prevents unintentional withdrawal of the pin from the hole. Preferably, the toggle (22) has arms of unequal length. <IMAGE>

Description

SPECIFICATION Pipe lifting devices This invention relates to pipe lifting devices and is particularly concerned with devices which can be used for lifting sections of concrete pipe.

Cylindrical sections of pipe, usually of concrete, are widely used in underground work, for example in the making of manholes and tunnels. In carrying out such work it is necessary to lift the sections of pipe into the underground excavation either from a vehicle or from a site above ground.

It may also be necessary to move such pipe sections from place to place above ground involving a lifting process. It is conventional to lift pipe sections of this nature by means of a chain and a crane or other lifting machine. It is conventional to couple the chain to the pipe section by means of a pair of eyeletted screws fitted through diametrically opposed holes in the pipe, with the screws being held in place by nuts fitting on to the screws internaliy of the pipe section. Such an arrangement has a number of disadvantages. Firstly, the structure of the eyeletted screws means that the lifting force is applied at right-angles to the axis of the screw via the chain, and this creates severe stress on the coupling mechanism.Additionally, in the conditions where such pipes are used it is extremely undesirable to have to fit nuts on to and remove nuts from screws or bolts or other fastening devices. The threads can become damaged, or alternatively caked with mud, cement, etc., rendering the coupling mechanism unusable. Furthermore, with any two-part coupling mechanism there is the danger that one of the parts will become lost, again leading to waste, additional expense, and a possible safety hazzard if a workman attempts to use a damaged coupling.

It is an object of the present invention to provide an improvded pipe lifting device which overcomes the disadvantages and drawbacks referred to above. It is an object of the present invention to provide a pipe lifting device which does not rely upon the use of screw-threaded fastenings to retain the device in place in the pipe section. It is a further, important object of the present invention to provide a pipe lifting device which cannot be misused and which will inherently function in a safe secure manner even if used by a careless workman.

In accordance with the present invention there is provided a pipe lifting device comprising a shaft portion adapted to be fitted through a hole in a section of pipe, means at one end of said shaft portion for coupling the device to lifting means, and a gravity-operated latching means at or adjacent ot the other end of said shaft portion to prevent unintentional withdrawal of the device from the hole.

In one preferred embodiment, the latching means comprises a toggle which is pivotable through less than 3600 about a pin extending perpendicular to the longitudinal axis of the shaft portion. Preferably, the other end of the shaft portion is bifurcated and the toggle is pivotally mounted between the bifurcations.

The gravity-operated action of the latching means can be achieved for example by using a double-armed toggle element having arms of unequal length. Alternatively or additionally, the toggle can be of non-uniform density, thereby to offset its centre of mass. This can be achieved for example by fitting an insert of a denser material than that of the toggle at or adjacent to one end of the toggle.

A presently preferred embodiment of pipe lifting device in accordance with the present invention will now be described by way of example and with reference to the accompanying drawing, in which: Fig. 1 is a side view of the lifting device showing the toggle element dropped into its latching position; and Fig. 2 is a top plan view of the lifting device showing the toggle element in its non-latching position for insertion into or removal from a pipe.

As shown in the drawings, the pipe lifting device comprises an elongate pin having a shaft portion 10 of cylindrical shape which terminates at one end in a generally rectangular crosssection block 12 which has a hole 14 therethrough extending perpendicular to the longitudinal axis of the shaft portion 10. The end of the pin remote from the block 12 is bifurcated to define two legs 1 6a and 1 6b with a recess 18 between them. The length of this recess 1 8 is shown as L. A fixed pin 20 extends across the recess 18 between the two legs and is secured at one or both ends, for example by welding.

Mounted on the pin 20 is a toggle element 22 in the form of a rectangular cross-section bar. This toggle element 22 is mounted so that it has two arms, extending one to each side of the pivot pin 20. The length of one of these arms is indicated at 1,, and the length of the other arm is indicated at 12. In the illustrated embodiment, 12 is greater than I1, which means that with a toggle element of uniform density the centre of mass of the toggle element is offset relative to the pivot pin 20 and in the absence of any other force exerted on the toggle element it will automatically pivot, due to gravity, into the position shown in Fig. 1.

The length L of the recess 18 is dimensioned to be greater than 1" but less than 12, so that the toggle element cannot rotate through a full 3600.

The longer arm of the toggle element cannot pass through the closed end of the recess 1 8, although the shorter arm is free to do so.

In practice, the lifting device shown in the drawings is intended to be used for lifting a pipe or section of pipe which has two diametrically opposed holes thorugh the pipe wall. To fit the lifting pin, the toggle element 22 is rotated until it is aligned with the shaft portion 10, and this end of the pipe can then be pushed through the hole n the pipe wall. As soon as the end of the lifting pin enters the free internal space within the pipe section, the toggle will undergo a gravity operated latching action and will rotate automatically to the position shown in Fig. 1. It will then be impossible to remove the lifting pin from the hole without positive manual realignment of the toggle.A shackle (not shown) having its shackle pin extending through the hole 14 in the block 12 can then be connected to a lifting chain (not shown) attached to a suitable crane or hoist. Using a pair of these lifting pins, one at each side of a pipe section, the pipe section can then be lifted safely and accurately.

In order to enhance the automatic latching action of the toggle 22 it is possible for example to fit an insert of a denser material into one end of the toggle. This can be done either with a toggle having arms of equal length or with toggles having arms of unequal length.

Although the lifting device of the present invention is designed primarily for use with concrete pipes, it is to be understood that it is not limited to that particular application, but could be used with pipes of other materials. For reasons of strength the lifting device of the present invention is preferably made of steel. The diameter of the cylindrical shaft portion 10 of the pin need be only slightly smaller than the diameter of the hole formed through the pipe wall.

Claims

1. A pipe lifting device comprising a shaft portion adapted to be fitted through a hole in a section of pipe, means at one end of the shaft portion for coupling the device to lifting means, and a gravity-operated latching means at or adjacent to the other end of the shaft Dortion to prevent unintentional withdrawl of the device from the hole.

2. A pipe lifting device as claimed in claim 1, in which the latching means comprises a toggle which is pivotable through less than 3600 about a pin extending perpendicular to the longitudinal axis of the shaft portion.

3. A pipe lifting device as claimed in claim 1 or 2, in which said other end of the shaft portion is bifurcated and a toggle element is pivotally mounted between the bifurcations.

4. A pipe lifting device as claimed in claim 3, in which the toggle element is mounted on a pivot pin and has a length between the pivot pin and one end thereof which is greater than the distance between the pivot pin and the closed end of the bifurcations.

5. A pipe lifting device as claimed in any preceding claim, in which the latching means comprises a pivotable double-armed toggle element having arms of unequal length.

6. A pipe lifting device as claimed in any preceding claim, in which the latching means comprises a pivotable element which is not of uniform density thereby to offset its centre of mass.

7. A pipe lifting device as claimed in claim 6, in which the pivotable element includes an insert of a denser material than that of the element.

8. A pipe lifting device as claimed in any preceding claim, in which the coupling means comprises an apertured block at said one end of the shaft portion and a shackle fastenable to the block and arranged to be connected to a lifting chain.

9. A pipe lifting device substantially as hereinbefore described with reference to the accompanying drawing.