GB2325455A

GB2325455A - Lifting device

Info

Publication number: GB2325455A
Application number: GB9800453A
Authority: GB
Inventors: Martin Tilley; Kevin Barry White
Original assignee: ANTHONY ROBSON COMMERCIAL SALE
Current assignee: ANTHONY ROBSON COMMERCIAL SALE
Priority date: 1998-01-10
Filing date: 1998-01-10
Publication date: 1998-11-25
Anticipated expiration: 2018-01-10
Also published as: GB2325455B; GB9800453D0

Abstract

A hydraulically operated portable lifting device 1 for lifting objects sunk into the ground comprises a hydraulic ram having a piston 6 and a cylinder 7 and at least one orifice (17,21; Figure 2) through which hydraulic fluid passes to move the piston 6 with respect to the cylinder 7. The device further comprises support means 2, and attachment means 4,38 to attach the device to an object to be lifted. Preferably the piston 6 is a hollow tubular rod and comprises an end plate (19; Figure 2). Preferably one chamber (18; Figure 2) is defined to one side of the end plate (19; Figure 2) between the rod 6 and the cylinder 7, and a second chamber (22; Figure 2) is defined to the other side of the end plate (19; Figure 2) between the cylinder 7 and the end plate (19; Figure 2), each of the chambers (18,22; Figure 2) being provided with an orifice (17,21; Figure 2) through which hydraulic fluid may pass to cause movement between the piston 6 and the cylinder 7. The support means 2 is preferably a horizontal plate, which is connected to the piston 6, and it may be "V" or crescent shaped. The attachment means 4,38, which may be a chain, belt or rope is preferably releasably attachable to the device using retaining means 5,36, the attachment device 4,38 being wrapped around the object to be lifted. The device 1 may also have handles 8,28.

Description

Lifting Device Field of the Invention This invention relates to a lifting device for use in extracting objects from the ground, and in particular to a lifting device for use in extracting telegraph poles or the like from the ground.

Background to the Invention Telegraph poles are used for carrying telephone cables (or similar), and are often found along roadsides. As such they present a hazard to motorists veering off roads. In order to mitigate the danger posed by telegraph poles, they are not set into hard core or concrete. To fix a telegraph pole into the ground a hole is dug, the base of the pole is dropped into the hole, and the hole is filled with earth. This method of fixing telegraph poles into the ground should allow them to move when hit.

In principal, when a vehicle hits a pole the pole should not shear off and fall backwards onto the vehicle, rather the pole should be pushed forwards away from the vehicle. However, when a telegraph pole has been in place for many years, as is the case with many telegraph poles, the earth that fills in the hole in which the pole sits tends to become compacted. The result is that when a vehicle hits the pole, instead of being pushed away from the vehicle, it shears off at ground level and falls backwards onto the vehicle. Such incidents have resulted in the death or serious injury of a number of motorists.

Another problem found with telegraph poles is that when they have been left in the ground for many years, the portion of the pole below the ground can rot. This eventually results in the pole falling over. However, it is often necessary for workmen to climb up poles in order to carry out work on the lines carried by the poles. If a pole were to fall over, the telephone, or electricity cable carried by the pole would be brought down, and the service provided through the particular cable would be disrupted. If a pedestrian or motorist were to pass beneath the pole, or if a workman were to be at the top of the pole at the moment it fell over serious injury or loss of life could occur.

It is therefore necessary to replace telegraph poles on a periodic basis so that there are no rotten telegraph poles and no telegraph poles that will not fall away from a striking vehicle.

It would be desirable to provide a lifting device to enable telegraph poles and the like to be extracted from the ground.

A hand-operated jack is available, but this suffers from a number of disadvantages. The jack is heavy, and the operator must stand in its vicinity when operating it There is therefore a danger to the operator if the chain or any other part of the machine were to break, or if the pole were to fall over during the course of being lifted.

It would therefore be desirable to provide a lifting device which does not suffer from the disadvantages suffered by known lifting devices.

Summary of the Invention The invention provides a hydraulically actuated portable lifting device for lifting objects sunk into the ground comprising a hydraulic ram having a piston and a cylinder and at least one orifice through which hydraulic fluid may pass to cause relative movement between the piston and the cylinder, the device further comprising support means, and attachment means to attach the device to an object to be lifted.

Preferably, the piston comprises an end plate and a piston rod, and more preferably a first chamber is defined to one side of the end plate between the rod and the cylinder, and to the other side of the end plate a second chamber is defined between the cylinder and the end plate, each of the chambers being provided with an orifice through which hydraulic fluid may pass to cause relative movement between the piston and the cylinder. A seal is suitably provided between the end plate and cylinder, for example an "O" ring. Preferably, the rod is concentrically located on the end plate. The rod is suitably hollow, and may comprise a tube. The open end of the cylinder is preferably provided with a first collar which is arranged to seal the rod of the piston and the cylinder. The collar may be releasably attached to the cylinder, preferably by screw threads. Advantageously, seals are provided between the collar and the cylinder, and the rod of the piston and the collar. The seals may be "0" rings.

Each of the said chambers is preferably provided with an orifice through which hydraulic fluid can flow.

In one embodiment of the invention a hydraulic connector suitable for connection to a pressurized supply of hydraulic fluid is provided for each said orifice. The hydraulic connector may include a valve which permits flow of hydraulic fluid into and out of the chamber. Preferably, a hose is provided for each connector, one end of each hose being connected to the device and the other end being connected to the pressurized supply. Advantageously, each hose is provided with at least one rupture protection valve. Each end of each hose may be provided with a rupture protection valve. The hydraulic connectors and hoses are suitably provided with male and female couplings.

Preferably, the support means comprises a plate which spreads the weight of the device and the object to be lifted. The plate is suitably flat. The plate may be substantially "V" or crescent shaped. The plate may be welded or otherwise fixed to the device, for example by means of screw threads. The support means may comprise one or more spikes.

The attachment means may comprise a flexible elongate member, and preferably one end of the said member is attached to the device and the other end of the said member is releasably attachable to a retaining means attached to the device. The flexible member may be a chain, a rope or a belt.

The device may further comprise a second collar so shaped and dimensioned as to fit around the cylinder. Advantageously, one end of the flexible elongate member is attached to the second collar, and the retaining means to which the other end of the flexible elongate member is releasably attachable is also attached to the second collar.

The retaining means may comprise a hook, a belt tensioner, or a clasp for example.

Preferably, the device is provided with a handle, which may be pivotally mounted on the device. Advantageously, a pair of handles is mounted on the device.

Preferably, the or each handle is mounted on the device serve to guard one of the hydraulic connectors.

The device of the invention is very simple and safe to use. Due to the device's low weight, an operator can carry it to a telegraph pole for instance. It is a very simple operation to attach the device to the telegraph pole. The operator need then only attach the hoses to the device and the source of pressurized hydraulic fluid. The operator can use the spool valves associated with the source of pressurized fluid to control the introduction of fluid into the first or second chambers. Fluid is supplied to the second chamber to extend the device and hence lift the object which is to be extracted. Due to the fact that an external pressurized hydraulic fluid supply is used, the operator can stand well away from the lifting device of the invention, and the object to be extracted.

It is therefore much safer to operate than known devices.

The device has very few moving parts, and is simple to maintain.

Brief Description of the Drawings In the drawings, which illustrate exemplary embodiments of the invention; Figure 1 is schematic representation of a pole extractor according to one embodiment of the invention; Figure 2 is a partial cross-section of the pole extractor shown in Figure 1; Figure 3 is a schematic representation of a pole extractor according to another embodiment of the invention; Figure 4 is a schematic representation of hydraulic hoses for use with the pole extractors shown in Figures 1 to 3; Figure 5 is a schematic representation of hydraulic hoses for use with the pole extractors shown in Figures 1 to 3; Figure 6 is a partial cross-section of a pole extractor according to another embodiment of the invention; Figure 7 is a plan view of the pole extractor shown in Figure 6; Figure 8 is a circuit diagram; and Figure 9 is a schematic representation of an alternative embodiment of the invention.

Detailed Description of the Preferred Embodiments Referring first to Figure 1, there is shown a hydraulically actuated lifting device 1 comprising a hydraulic ram having a piston 6 and a cylinder 7. Screwed into the piston 6 is an support means formed from a "V" shaped metal plate 2, the lower edge 3 of which extends horizontally to provide a flat surface which may rest on the ground and prevent the device from sinking when used. The support means may be formed from a crescent shaped metal plate. At each side of the plate 2, there is attached a bracket 5.

A chain 4 is attachable to each bracket 5. When the device 1 is placed next to an object to be extracted, with the chain 4 attached to one of the brackets 5, the chain 4 is passed around the object and attached to the other bracket 5 to ensure that the device 1 does not slip away from the object to be lifted.

Affixed to the cylinder 7 at the upper end thereof is an end cap 23. Attached to either side of the end cap 23 are shackles 36. A chain 38 is attached to one of the shackles, whilst a hook is attached to the other. The end cap 23 is also provided with a handle 28 which is mounted on a boss 24 attached to the end cap. A boss 9 is attached to the lower portion of the cylinder 6 and has a handle mounted thereon. The boss 24 is described in greater detail with reference to Figure 2. The handles 8 and 28 guard the bosses 9 and 24 respectively, and prevent the hydraulic components 10, 11 and 25, 26 from being damaged in the event of the device falling over. In order to avoid damage to the handles during lifting, the cylinder 7 may be rotated about piston 6, so that the handles do not face the object to be lifted.

Referring now to Figure 2, relative movement between the piston and the cylinder, and hence extension and retraction of the device is controlled by flow of hydraulic fluid into or out of the respective chambers 18 and 22. As hydraulic fluid is introduced into the chamber 22, the hydraulic fluid is forced out of the chamber 18 and the device extends. When hydraulic fluid is introduced into the chamber 18, it is forced out of the chamber 22 and the device retracts.

It can be seen from Figure 2 that the piston 6 is hollow. By providing a hollow piston, the overall weight of the device is reduced, thereby allowing it to be carried and easily handled by an operator.

The lower end of cylinder 7 is threaded 16 internally. A collar 12 having an externally threaded portion 15 is screwed into the lower end of the cylinder 7. An "O" ring 1 3 is fitted around the collar 12 so as to prevent oil leakage. The inner circumferential edge of the collar 12 is provided with a groove in which an "0" ring 14 sits. This prevents any leakage from the chamber 18 between the piston 6 and the cylinder 7.

The upper end of the piston 6 is provided with a plate 19, the thickness of which is sufficient to withstand the pressure exerted on it by the hydraulic fluid. A groove is provided on the outer circumferential edge of the plate 19, and an "0" ring 20 is located therein to prevent leakage of hydraulic fluid from chamber 22 to chamber 18 or vice versa.

Hydraulic fluid enters the chambers 18 and 22 through bores 17 and 21 respectively. These bores extend through the sidewall of the cylinder 7 (and end cap 23 in the case of bore 21) and through bosses 9 and 24 respectively. Attached to the boss 9 is one end of a hydraulic coupling 11, the other end of the coupling 11 having a female hydraulic connector 10 attached thereto. One end of a hydraulic coupling 25 is attached to the boss 24, the other end of the coupling having a male hydraulic coupling 26 attached thereto.

In Figure 4, two flexible hydraulic hoses 70, 73 are shown. Hose 70 has male connectors attached to each end thereof, whereas hose 73 has female connectors attached to each end thereof. One of the end portions of each of the hoses 70, 73 is provided with a rupture protection valve 72, 75. The rupture protection valves 72, 75 each comprise a check valve, and are designed to allow hydraulic fluid to flow out of the device at a predetermined rate. In the event of the hose 70, 73 rupturing the hydraulic fluid would escape at a rate greater than permitted by the valves 72, 75. The valves detect this and close, thereby preventing fluid from escaping.

Figure 5 shows two flexible hydraulic hoses 80, 83. Hose 80 has male connectors attached to each end thereof, whereas hose 83 has female connectors attached to each end thereof. Both end portions of each of the hoses 80, 83 are provided with rupture protection valves.

ln use, an operator carries the lifting device, using handles 8, 25, to the vicinity where it is to be used. The device is placed next to an object to be lifted, for example a telegraph pole. The chain is then brought around the front of the object and attached to the hook 27. The chain can be of any desired length. The male connector 71 of hydraulic hose 70 is inserted into the female hydraulic connector 10, and the female connector 74 of hydraulic hose 73 is fitted onto the male connector 26. In each case the hydraulic connector adjacent the rupture protection valve 72, 75 is connected to the lifting device. Alternatively, hoses 80, 83 may be used in place of hoses 70, 73. The opposite ends of the hoses 70, 73 are connected to a supply of pressurized hydraulic fluid, for example a truck or an excavator. It will be noted that the device is not pro vided with any control valves. This is because control valves on the hydraulic fluid sup ply are used to regulate flow into and out of chambers 18 and 22 of the device. By using these controls, the device 1 can be actuated remotely. This is advantageous for a number of reasons. First, if chain 28 were to break the operator would be at a safe distance away from the chain, thereby avoiding the possibility of being hit by a piece of metal. Second, occasionally, the device and the object to which it is attached may fall over, because the object, for example a telegraph pole, might be rotten. Again, by being a safe distance away from the object the operator is unlikely to be injured by the object falling over. Whilst this is unlikely, because the object being extracted should be supported from above, by a crane for example, there are foreseeable circumstances where the object may fall over.

When the operator allows hydraulic fluid into chamber 22, the device is caused to extend. First this takes up any slack in chain 28, and then the chain grips the object and lifts it vertically. in the case of telegraph pole it is not necessary for the pole to be lifted through a great height. The main purpose of lifting is to dislodge the pole so that it can then be lifted with a crane or similar.

Figure 3 illustrates a hydraulically actuated lifting device 40 comprising a hydrau- lic ram having a piston 44 and a cylinder 59. Screwed to the piston 44 is an support means formed from a "V"shaped metal plate 41, the lower edge 42 of which extends horizontally to provide a flat surface which may rest on the ground and prevent the device from sinking when used. The support means may be formed from a crescent shaped metal plate. Affixed around the cylinder 59 is a collar 45. A shackle 57 is attached to one side of the collar 45, and bored tube 46 is attached to the other. A belt tensioner 47 is pivotally attached to the tube 46 by a bolt which passes through the bore in tube 46, and is secured by nut 53. Attached to shackle 57 by means of pin 58 is a chain link 56, the rod 64 of which is removable to allow other chains, such as link 55 to be attached thereto.

Handles 60, 63 are attached to bosses 61, 66 respectively. The boss 61 mounts the male hydraulic connector 64, while boss 66 mounts female hydraulic connector 65.

The handles 60, 63 act as guards, guarding the hydraulic components mounted on the bosses 61, 66 respectively.

To attach the device 40 to a telegraph pole for example, the buckle 54 is attached to link 55, and the strap 53 is attached to the belt tensioner 47. The belt is then tensioned using tensioner 47.

The plate 41 has a pair of hooks 43 attached to its inner surface, so that a second attachment means, such as a chain, may be fitted around the object.

To operate the device 40, one end of each hydraulic hose 73 and 70 is attached to male and female connectors 64 and 65 respectively, the other end being attached to a controllable hydraulic fluid supply. The piston 44 and cylinder 59 of the device 40 are arranged, and the device is extended and retracted in the same manner as described with reference to Figures 1 to 3.

Referring now to Figures 6 and 7, there is shown a lifting device similar to that shown in Figures 1 and 2, and like numerals are used to refer to like parts. Hydraulic fluid is supplied to both chambers 18 and 22 through a pilot operated check valve 90.

The pilot operated check valves are known and therefore the constructional details of the valve 90 will not be discussed in detail.

To operate the device shown in Figures 6 and 7, hydraulic fluid is supplied through hydraulic connector 94, the fluid flowing through bore 96 and through a check valve (not shown) arranged to permit fluid to flow from bore 96 and into chamber 22.

The check valve is mounted in bore 97. Hydraulic fluid contained in the chamber 18 is forced through orifice 17, pipe 91 which is connected thereto, and hydraulic connector 93. The Piston 6 and cylinder 7 are thereby moved apart.

When lowering the device, fluid must flow out of chamber 22 and into chamber 18. The pilot operated check valve must allow the fluid contained in chamber 22 back through the check valve mounted in aperture 97. A bleed line takes hydraulic fluid supplied through hydraulic connector 93, and provides hydraulic pressure to the check valve which is sufficient to lift it off its seat. The remainder of the hydraulic fluid entering through hydraulic connector 93 passes through the pipe 91, orifice 17 and into chamber 18. For the device to retract, there must be pressure in the bleed line. If there is no pressure in the bleed line, the check valve will not be lifted off its seat, and therefore fluid will not be able to flow through the orifice 90 and bore 96. Hence, the piston can only be retracted into the cylinder if fluid is being fed positively into the chamber 18; otherwise the piston is locked in position.

In Figure 7, it can be seen that first guard 92, in the form of angle sectioned steel is provided to protect the pipe 91, that a second guard 95 is fixed to the top of collar 23 to protect the hydraulic connectors 93, 94.

The hydraulic circuit of the check valve is shown in Figure 8. C1 and C2 correspond to orifices 17 and 97 respectively, V1 and V2 represent the hydraulic supplies to which connectors 93 and 94 are connected to respectively. The bleed line is represented by the broken line.

Referring now to Figure 9, there is shown a device 1 having a check valve 90 mounted thereon with hydraulic connectors 93, 94. A guard 95 is fixed to the collar 23 to protect the hydraulic connectors 93, 94. A chain 101 comprising a plurality of similar links 102 and a substantially circular link 103 is attached to a U-shaped member extending from the collar 23. A pin 103 passes through one of the upright portions of the U-shaped member, through one of the links 102, and through or into the other up right of the U-shaped member 100 to secure the chain 101 thereto. In use, the device 1 is placed next to the object to be lifted. The pin 103 is removed, and the chain 101 is wrapped around the object and one end of the chain is threaded through the substan- tially circular link 103. One of the links 101 is placed in the slot provided by the Ushaped member 100 and the chain is attached thereto as described above. As the device is lifted the chain acts as a noose around the object to be lifted.

Claims

1. A hydraulically actuated portable lifting device for lifting objects sunk into the ground comprising a hydraulic ram having a piston and a cylinder and at least one orifice through which hydraulic fluid may pass to pass to cause movement between the piston and the cylinder, the device further comprise ing support means, and attachment means to attach the device to an object to be lifted.

2. A lifting device according to Claim 1, wherein at least a portion of the piston is hollow.

3. A lifting device according to Claim 1 or 2, wherein the piston comprises an end plate and a rod, and wherein a first chamber is defined to one side of the end plate between the rod and the cylinder, and to the other side of the end plate a second chamber is defined between the cylinder and the end plate, each of the chambers being provided with an orifice through which hydraulic fluid may pass to cause movement between the piston and the cylinder.

4. A lifting device according to Claim 3, wherein the rod comprises a tube.

5. A lifting device according to any preceding claim, wherein the open end of the cylinder is provided with a first collar which is arranged to seal the rod of the piston and the cylinder.

6. A lifting device according to Claim 5, wherein the collar is releasably attach able to the cylinder.

7. A lifting device according to any of Claims 2 to 6, further comprising a pilot operated check valve, wherein fluid passing into and out of the first and sec ond chambers passes through the said valve, and wherein hydraulic fluid may not pass out of the first chamber if the check valve is not lifted off its seat by a pilot pressure applied thereto.

8. A lifting device according to any preceding claim, wherein a hydraulic con nector suitable for connection to a pressurized supply of hydraulic fluid is provided for each said orifice.

9. A lifting device according to Claim 8, wherein the hydraulic connector in cludes a valve which permits flow of pressurized hydraulic fluid through the said orifice.

10. A lifting device according to Claim 8 or 9, wherein a hose is provided for each connector, one end of each hose being connected to the device and the other end being connected to the pressurized supply.

11. A lifting device according to Claim 10, wherein each hose is provided with at least one rupture failure valve 12. A lifting device according to Claim 11, wherein each hose is provided at each end thereof with a rupture failure valve.

13. A lifting device according to any of Claims 8 to 12, wherein the hydraulic connectors and hoses are provided with male and female couplings.

14. A lifting device according to any preceding claim, wherein the support means comprises a plate.

1 5. A lifting device according to Claim 14, wherein the plate extends horizon tally to spread the load carried thereby.

16. A lifting device according to Claim 14 or 15, wherein the plate is substan tially "V" or crescent shaped.

17. A lifting device according to any preceding claim, wherein the device further comprises a second collar so shaped and dimensioned as to fit around the cylinder.

18. A lifting device according to any preceding claim, wherein the attachment means comprises a flexible elongate member.

19. A lifting device according to Claim 18, wherein at least one end of the said attachment means is releasably attachable to the device.

20. A lifting device according to Claim 19, wherein one end of the said member is attached to the device and the other end of the said member being releas ably attachable to a retaining means attached to the device.

21. A lifting device according to any of Claims 18 to 20, wherein the flexible member is a chain, a rope or a belt.

22. A lifting device according to Claim 21, wherein one end of the flexible member is provided with an enlarged portion through which the other end of the said flexible member may be passed.

23. A lifting device according to any of Claims 20, wherein the retaining means comprises a hook, a belt tensioner, or a clasp.

24. A lifting device according to any preceding claim, wherein the device is pro vided with a handle.

25. A lifting device according to Claim 24, wherein the handle is pivotally mounted on the device.

26. A lifting device according to Claim 24 or 25, wherein the handle forms a guard.

27. A lifting device substantially as described with reference to, or as shown in, the drawings.

Amendments to the claims have been filed as tolows 1. A hydraulically actuated hand-portable pole lifting unit for lifting poles par tially sunk into the ground, the unit comprising a hydraulic ram having a pis ton and a cylinder and at least one orifice through which hydraulic fluid may pass to cause relative movement between the piston and the cylinder, ground engaging support means, and attachment means to attach the unit to a part of a pole to be lifted which is above the ground, wherein the ground engaging support means and attachment means are each attached to the hy draulic ram, one being attached to the piston and the other being attached to the cylinder, and wherein the said ground engaging support means is at tached to a free end of either the piston or the cylinder, in use the said at tachment means being above the said ground engaging support means, characterized in that with the ground engaging support means attached to a said free end of either the piston or the cylinder the unit may be readily car ried.

3. A lifting device according to Claim 1 or 2, wherein the piston comprises an end plate and a rod, and wherein a first chamber is defined to one side of the end plate between the rod and the cylinder, and to the other side of the end plate a second chamber is defined between the cylinder and the end plate, each of the chambers being provided with an orifice through which hydraulic fluid may pass to cause said movement between the piston and the cylinder.

4. A lifting device according to Claim 3, wherein the rod comprises a tube.

5. A lifting device according to Claim 3 or 4, wherein the open end of the cyl inder is provided with a first collar which is arranged to form a seal between the rod of the piston and the cylinder.