GB2273090A

GB2273090A - Lifting device and method

Info

Publication number: GB2273090A
Application number: GB9324706A
Authority: GB
Inventors: Walter Snaith Sample
Original assignee: SAHLINS CLYDESDALE Ltd
Current assignee: SAHLINS CLYDESDALE Ltd
Priority date: 1992-12-02
Filing date: 1993-12-02
Publication date: 1994-06-08
Also published as: GB9324706D0

Abstract

A device (40) for use in lifting and/or lowering objects up or down a pole (4) comprises a frame (42, 48, 50) for mounting the device on a pole and rope guides (60, 66) supported on the frame. The arrangement of the device is such that a rope can pass over the guides and up and down two opposite sides of the pole, while both of these sides are effectively unobstructed by the frame (48) of the device. A clamp device may be attached to the object to be raised (lowered). The clamp grips the object at spaced-apart points and has a central attachment point or guide around which a rope may be passed. Means are provided by which the lifting operation may be performed at a safe distance from the foot of the pole. The device is used for lifting new crossbows onto power transmission or telephone lines. <IMAGE>

Description

LIFTING DEVICE AND METHOD The present invention relates to a lifting device for aiding lifting of objects to, or lowering of objects from, the top of a pole. It also relates to a method of lifting objects to, or lowering objects from, the top of a pole. Embodiments of the invention have a particular application in the lifting and lowering of cross-arms to the top of poles used for carrying electricity or telephone wires.

Poles carrying electricity or telephone wires are often situated in remote areas, and it is sometimes difficult to obtain access by mechanical lifting means. Typically, near the top of each pole is detachably fixed a horizontal "cross-arm", to which are fitted a number of insulators. The electricity or telephone wires carried by the pole are mounted on the insulators.

On a number of poles, a single cross-arm has been provided. However, experience has shown that in many cases, it is necessary to have two cross-arms, one fixed each side of the pole and connected to each other, in order to provide rigidity in times of high winds and the like. Thus, there is a need to fit an additional crossarm to many poles. In addition, cross-arms are typically made of mild steel, which rusts, limiting the service life of the cross-arm. An average service life is typically 50 years. Accordingly, there is a continuing need to replace the cross-arms on poles carrying electricity or telephone wires.

In the art, there is known a lifting device comprising a roller and a mounting bracket. The bracket attaches to one side of the pole, and the roller sits on top of the pole with its axis of rotation in a horizontal plane.

A rope is passed over the roller and is attached to a cross-arm to be lifted. The cross-arm is lifted by pulling on the free end of the rope so that it is raised alongside a side of the pole remote from the side to which the bracket is attached. Such a device suffers from a number of problems.

Firstly, since a cross-arm complete with insulators typically weighs 300kg, and a cross-arm without insulators typically weighs 100kg, considerable effort is required to lift the cross-arm from the ground to the top of the pole, which is typically between 8m and 14m high.

Secondly, in a case where two cross-arms are to be provided at the top of the pole, the bracket of the lifting device occupies a part of the pole where the second cross-arm must be attached. Since the device cannot be turned round once the first cross-arm is in place to allow the second cross-arm to be lifted, because the first cross-arm prevents the bracket being attached to the pole, the only way that such a device can be used to fit two cross-arms is to lift the second cross-arm with the device in its original position for lifting the first cross-arm, then to support the second cross-arm at the top of the pole while the lifting device is removed to allow attachment of the second cross-arm to the pole.

Given the weight of a cross-arm, this method is not practical.

In addition to the problems described above, there are also further problems. A cross-arm has a length of approximately 2.1m. When lifting the cross-arm, the rope is usually attached via a hole in the cross-arm or via a support pin on which is mounted an insulator. During the lifting operation, the cross-arm is prone to slewing.

Further, when the cross-arm has been raised to the top of the pole, it is often difficult to insert the locking bolt, which passes through a hole in the cross-arm and a pre-drilled hole in the pole before being secured by a nut on the other side of the pole, due to the attachment of the lifting rope.

The present invention has been made with the aim of solving one of more of these problems in mind.

According to a first aspect of the invention, a device for use in mounting and/or de-mounting objects on a pole is constructed such that objects can be mounted on first and second opposing faces of the pole, while the device is attached to a different, third face of the pole.

In embodiments of the invention, the lifting device provides a low-friction guide oriented transversely of the device such that a rope can pass through the guide and across the top of the pole up and down two opposite sides of the pole, while both of these sides are effectively unobstructed by the mounting of the device.

By leading the rope transversely, such a device reduces the chance that the rope or the object being lifted will collide with the device itself. It is then possible, when necessary, to mount or de-mount cross-arms or other two objects, unobstructed, on two opposite sides of the pole in turn, while the device remains fixed in one place.

In another aspect, the invention provides a clamp for use in raising or lowering a cross-arm or other object up or down a pole. The clamp can reduce slewing of the object while it is suspended, and/or can permit the object to be mounted against the pole while suspended, without risk of the rope getting trapped or causing obstruction.

In exemplary embodiments, the clamp has a central attachment point for a rope, and grips the object at a plurality of spaced-apart points. Instead of an attachment point, the clamp may be provided with a lowfriction guide, which the rope can pass around.

The invention also provides methods of mounting and demounting objects to poles, for example, such that a lifting device is mounting on a first face of the pole, while one or two objects are mounted on second and/or third faces which are not the same as and not diametrically opposite the first face.

There may be employed a device mounted at the top of the pole and a device mounted on the object being lifted, and an arrangement of a rope and low-friction guides therefor, so as to gain a reduction in the force necessary to raise the object, for example by a factor of two or more. In one example of such a method, the rope is passed over a low-friction guide in the device at the top of the pole, down and through a low-friction device mounted on the object, and back up the pole to be fixed to the device at the top of the pole. Of course, other arrangements of the rope are possible.

In a further aspect, the invention provides means for enabling an object to be lifted or lowered up (down) a pole while the operator maintains a safe distance from the foot of the pole.

In embodiments of the invention, this means may comprise an eye bracket which is attached at or near the base of the pole or in the ground, and through which the rope used for the lifting (lowering) operation passes. Such an arrangement of bracket and rope allows the rope to be controllably pulled or released from a safe distance without exerting a force on a rope guide means mounted at or near the top of the pole which may weaken the mounting of such rope guide means or even pull the rope guide means from the pole.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 shows an arrangement of poles carrying cross-arms and wires; Fig. 2 shows cross-arms typically mounted near the top of a pole; Fig. 3A is a perspective view of a lifting device; Fig. 3B is an enlarged perspective view of an attachment arrangement of the lifting device shown in Fig. 3A; Fig. 4 shows a lifting device attached to the top of a pole; Fig. 5 shows a perspective view of a clamp device; Fig. 6 is a first elevation view showing the clamp device in Fig. 5 attached to a cross-arm; Fig. 7 is a second elevation view showing the clamp device in Fig. 5 attached to a cross-arm; Fig. 8 illustrates a method of replacing cross-arms on a pole; Fig. 9 shows a step in the method of Fig. 8 where a cross-arm is fixed to the pole; and Fig. 10 shows arrangements by which the lifting (lowering) operation may be carried out at a safe distance from the foot of the pole.

Referring now to the drawings, Fig. 1 shows a typical arrangement of poles 2, 4, 6. Each pole carries two cross-arms 8, 10 near its upper end. Two such cross-arms are shown in Fig. 2. Each cross-arm has an L-shaped cross-section, comprised of a horizontal part 5 approximately 152mm wide and a vertical part 7 approximately 102mm wide. The cross-arms 8, 10 are connected to the pole via a bolt (not shown) which passes through the hole 9 in each cross-arm and through a first pre-drilled hole (not shown) in the pole. A nut (not shown) is fitted on the bolt to lock the cross-arms. In addition, support struts 12 (shown in Fig. 1) secure the cross-arms to the pole.The support struts 12 connected to the cross-arm 8, and the support struts 12 connected to the cross-arm 10 are rigidly secured to each other and the pole by passing a second bolt (not shown) through a hole (not shown) in the first pair of support struts, a second pre-drilled hole in the pole, and a hole (not shown) in the second pair of support struts, and tightening a nut on the bolt. The second pre-drilled hole in the pole runs parallel to the first pre-drilled hole, and at a lower height on the pole.

On the cross-arm 10 are mounted a plurality of insulators 14. In this example, two insulators 14 are shown. The insulators 14 are mounted on support pins 11. The crossarm 8 is identical to the cross-arm 10, except that it has no insulators 14 or support pins 11.

Supported on each insulator 14 is a continuous wire 16, which runs between the poles 2, 4, 6. On the top of each pole is an angled cap 18, which assists in the drainage of water from the top of the pole, thereby preventing rotting of the pole.

For the purpose of illustrating an embodiment of the invention in use, it is assumed that there is a requirement to change the cross-arms 8, 10 on the centre pole 4 shown in Fig. 1.

Fig. 3A shows a lifting device 40 which is used to assist the replacement of the cross-arms 8, 10. The lifting device 40 comprises a frame portion 42, a low-friction guide portion 44 and a cable retaining portion 46.

The frame portion 42 has a first part 48 and a second part 50 arranged approximately perpendicular to each other, thereby giving the frame portion 42 a substantially L-shaped configuration. The first part 48 comprises side bars 52 and connecting bars 54. The side bars 52 and connecting bars 54 are preferably made from a strong, lightweight material. In this embodiment, for example, the side bars 52 and connecting bars 54 are made from hollow aluminium tube, having a rectangular crosssection. The walls of the tube are approximately 3mm thick. The second part 50 comprises a plate 56 which is rigidly connected to the first part 48 via a connecting block 58. It is preferable that the plate 56 and connecting block 58 are made from a strong, lightweight material, for example, aluminium.In this example, the plate 56 is made from an aluminium plate having a thickness of approximately 6 to 7mm. All of the connections within the frame portion 42, that is, between the side bars 52 and connecting bars 54, between the side bars 52 and the connecting block 58, and between the connecting block 58 and the plate 56 are provided by welding.

The low-friction guide portion 44 comprises roller means 60 and frame plates 62. The frame plates 62 are connected to a column 64 which is mounted on the frame portion 42 via the connection block 58 and the plate 56.

The roller means 60 are made from alloy metal, and are mounted on a high-tensile steel spindle. Each roller means 60 has an indentation 66 for accepting a rope or other cable-type member. The frame plates 62 and column 64 are made from a strong, lightweight material, for example aluminium. Connections between components are provided by welding.

The low-friction guide portion 44 is arranged such that the column 64 and frame plates 62 hold the roller means 60 in a configuration such that a rope slung over the roller means 60 would hang in a plane parallel to the plane of the first part 48 of the frame portion 42.

The cable retaining portion 46 comprises support plates 68, a pin 70 connected between the support plates 68, and a removable peg 72. The support plates 68 are connected to the frame plates 62 and the column 64. The peg 72 may be inserted and removed through holes 74 in the support plates 68. When the peg 72 is fully inserted, the pin 70, the upper ends of the support plates 68 and the peg 72 define an enclosed region 76. The components of the cable retaining portion 46 are made from a strong, lightweight material, for example aluminium.

Also provided on the lifting device 40 are attachment arrangements 61 for securing a rope or other cable-type member to. The attachment arrangements 61 must be capable of supporting a high load since, as will be described later, in operation an attachment arrangement 61 supports some of the weight of a cross-arm 8, 10. An attachment arrangement 61 provided in this embodiment is shown in Fig. 3B. The attachment arrangement 61 comprises a U-shaped bracket 63 and a locking pin 65.

The U-shaped bracket 63 fits on the outside of the frame plates 62. The locking pin 65 is inserted through clearance hole 67 in the bracket 63 and clearance holes 69 in the frame plates 62. The threaded end 71 of the locking pin 65 is then screwed into the threaded hole 73 of the bracket 63. This configuration of attachment arrangement 61 provides high strength and allows the bracket 63, to which is secured a rope or other cabletype member, to swing to accommodate changes in the angle of the attached rope or other cable-type member. The components of the attachment arrangement should be provided from strong materials. In this embodiment, the bracket 63 and locking pin 65 are made from high-tensile alloy steel. The frame plates 62 are made from aluminium.

In operation, the device 40 is mounted on top of the angled cap 18 on top of the pole 4 as shown in Fig. 4.

The device 40 is arranged such that the second part 50 of the frame portion 42 sits on top of the cap 18, with the plate 56 resting on the cap 18. With this arrangement, the force exerted on the lifting device 40 when an object is raised using a rope or other cable-type member slung over the roller means 60 is directed down through the centre of the pole. The first part 48 of the frame portion 42 extends parallel to one side of the pole 4. The device 40 is detachably secured to the pole 4 using straps 100 which are wrapped around both the pole 4 and first part 48 of the frame portion 42 before being pulled tight and secured. In one embodiment, the straps 100 are nylon ratchet straps to which are fixed hooks (not shown). In operation, the hooks are connected to slots (not shown) provided in the frame portion 42 of the lifting device 40.

Fig. 5 shows a clamp device 110 which is used to assist in the replacement operation. The clamp device 110 comprises two substantially U-shaped brackets 112 connected at one end by a cylindrical member 114 and at the other end by a locating plate 116. A second locating plate 118 is provided at a predetermined position with respect to the first locating plate 116 using connection brackets 120. Between the connection brackets 120 is mounted a low-friction guide member 122. Preferably, the guide member 122 is rotatable between the brackets 120.

In this embodiment, the guide member 122 comprises a rotatable roller made from alloy metal and mounted on a high-tensile steel spindle. Two locating blocks 126 are provided on the brackets 112 to guide screw members 124 at predetermined angles with respect to the locating plates 116, 118. The screw members 124 are moved using the attached handle mechanism 128.

It is preferable that the components of the clamp device 110 are made from strong, lightweight materials. In this embodiment, the brackets 112, locating plates 116, 118 and connection brackets 120 are cut from aluminium plate and have a thickness of approximately 20mm. The cylindrical member 114 and locating blocks 126 are also made from aluminium. The screw thread within the locating blocks 126 is provided by a stainless steel helicoil insert. The screw members 124 are made from stainless steel. Connections between the components of the clamp device 110 are formed by welding.

In operation, the clamp device 110 is attached to a cross-arm 8, 10 to be lifted or lowered, as shown in Fig.

6 and Fig. 7. To connect the clamp device 110 to a cross-arm 8, 10, the screw members 124 are first retracted. Then, the horizontal part 5 of the cross-arm 8, 10 is inserted through the brackets 112. The device 110 is moved along the cross-arm 8, 10 until the hole 9 in the vertical part 7 of the cross-arm 8, 10 is between the brackets 112, as shown in Fig. 7. The clamp device 110 is then arranged so that the top surface of the horizontal part 5 of the cross-arm 8, 10 rests adjacent the lower surface of the locating plate 116, and the outer edge of the vertical part 7 of the cross-arm 8, 10 rests adjacent the inner surface of the locating plate 118, as shown in Fig. 6. With the clamp device 110 held in this position, the screw members 124 are tightened.

The locating blocks 126 ensure that the screw members 124 are arranged at an angle such that they contact the cross-arm 8, 10 at the inner corner 125 thereof. Each screw member 124 has a formed head 127 to ensure that the cross-arm 8,10 is rigidly held by the formed head 127 contacting the inner corner 125.

The way in which the cross-arms 8, 10 on the pole 4 shown in Fig. 1 are replaced by new cross-arms will now be described with reference to Figs. 8 and 9.

The lifting device 40 is first connected to the top of the pole 4 as shown in Fig. 8A. The lifting device 40 is attached by means of straps 100 as shown in Fig. 3A.

The peg 72 of the device 40 is then removed from the holes 74 (Fig. 3A). The wires 16 are removed from the insulators 14 mounted on the cross-arm 10 and are placed on the pin 70 of the device 40 between the support plates 68. The peg 72 is then reinserted in the holes 74, thereby retaining the wires 16 in the enclosed space 76 during the replacement of the cross-arms 8, 10. The clamp device 110 is then secured to the first existing cross arm to be lowered, in this case, the cross-arm 8.

A rope 150 is slung across the roller means 60 of the lifting device 40. One end of the rope 150 is threaded beneath the low-friction guide member 122 of the clamp device 110 and is then tied to an attachment arrangement 61 of the lifting device 40 at the top of the pole. The other end of the rope 150 is lowered to the ground. The frame plates 62 have a configuration that holds the roller means 60 in such a position that the outer edges of the roller means 60 are clear of the edges of the pole 4. In this way, the rope 150 hangs clear of the pole 4. The arrangement of the pole 4, cross-arms 8, 10, lifting device 40, clamp device 110 and rope 150 after these steps is shown in Fig. 8B.

The support struts 12 supporting cross-arm 8 are then removed. The support bolt (not shown) which locks the cross-arms 8, 10 together and to the pole is then loosened to facilitate removal of the cross-arm 8. As shown in Fig. 8C, the cross-arm 8 is then removed from the support bolt (now shown) and lowered to the ground by controllably releasing the rope 150.

The steps described above are then repeated to lower the remaining cross-arm 10. The state of the pole 4 is then as shown in Fig. 8D.

The steps involved in fitting new cross-arms 8A, 10A will now be described.

A clamp device 110 is attached to the first new cross-arm to be lifted, in this case cross-arm 8A. One end of the rope 150 is threaded beneath the low-friction guide member 122 of the clamp device 110 and is then tied to an attachment arrangement 61 of the lifting device 40, which remains attached to the top of the pole 4. The other end of the rope 150 is slung between the roller means 60 of the lifting device 40 and is allowed to hang at ground level. This arrangement is shown in Fig. 8E.

Next, as shown in Fig. 8F, the cross-arm 8A is raised by pulling on the free end of the rope 150. Once the crossarm 8A is at the correct height, a bolt 152 is inserted through the hole 9 in the vertical part 7 of the crossarm 8A and into the pre-drilled hole 154 provided in the pole 4. This step is best seen in Figs. 7 and 9. Since, as described previously, the hole 9 in the vertical part 7 of the cross-arm 8A is arranged to lie between the brackets 112 (as shown in Fig. 7), the bolt 152 is inserted through the holes 9 and 154 without being obstructed by any part of the clamp device 110. As shown in Fig. 9, the bolt is inserted into the hole 154 such that it does not protrude beyond the lip of the hole 154 at the far side of the pole 4. Next, the cross-arm 8A is secured in a manner that prevents it rotating about the bolt 152. This may be done, for example, by connecting the support struts 12 to the cross-arm 8A and pole 4. This is done by inserting a bolt (not shown) through holes in the lower ends of the support struts 12 and through a second predrilled hole (not shown) in the pole 4. The bolt is inserted into the second predrilled hole such that it does not protrude beyond the lip of the hole on the far side of the pole.

The lifting operation described above is then repeated to lift new cross-arm 10A, as shown in Fig. 8G and Fig.

8H. The clamp device 110 may be removed from the crossarm 8A and fixed to the cross-arm 10A for use in this operation. Alternatively, a second clamp device 110 may be used for the cross-arm 10A and both clamp devices may then be removed once the replacement of both cross-arms is complete. In this embodiment, the column 64 of the lifting device 40 is arranged to have a height suitable to hold the roller means 60 a sufficient distance above the fixed cross-arm 8A that the free end of the rope 150 has to be moved only a small distance away from the base of the pole 4 to ensure that the rope 150 does not catch on the fixed cross-arm 8A as the cross-arm 10A is raised.

In this embodiment, the column 64 has a height of 270mm.

When cross-arm 10A is at the desired height, the bolt 152 is pushed further into the hole of 154 so that it protrudes beyond the lip of the hole 154 at the far side of the pole 4 and into the hole 9 in the vertical part 7 of the new cross-arm 10A, thereby supporting the crossarm 10A. A nut (not shown) is then fitted on the bolt 152 and tightened. The support struts 12 for cross-arm 10A are then connected and the necessary interconnections made between the two cross-arms 8A and 10A.

The peg 72 is then removed from the holes 74 in the lifting device 40 and the wires 16 are removed from the space 76 and mounted on the insulators 14 on the crossarm 10A. The lifting device 40 may then be removed from the pole, the replacement of the cross-arms being complete, as shown in Fig. 81.

The embodiment described above provides a number of advantages. Firstly, use of the lifting device 40 enables two cross-arms to be lifted and attached to the top of a pole. In this operation, the lifting device 40 does not have to be removed from the pole. Secondly, since the rope 150 is passed around the cross-arm to be lifted by using the low-friction guide member 122 and is attached to a point at the top of the pole using the attachment arrangement 61 on the lifting device 40, the effective weight of the cross-arm to be lifted is reduced.

In addition, the use of the clamp device 110 reduces the amount by which a cross-arm slews during lifting and lowering, and also ensures that the support bolt 152 can easily be inserted through the hole 9 in the cross-arm and the predrilled hole 154 in the pole.

The lightweight construction of the lifting device 40 ensures that it is portable and can be easily raised to the top of the pole where it is to be secured. The strong materials and connections provided in the lifting device 40 and clamp device 110 ensure that both devices are adapted for the high pressures and weights that they are subjected to during the lifting and lowering operations.

A number of modifications which could be made to the lifting device 40, the clamp device 110 and the method of lifting an object to, and lowering an object from, the top of a pole will now be described.

Firstly, although the lifting device in the embodiment above is described as having two roller means 60, a single roller member could be provided, for example with its centre above the centre of the pole.

In the embodiment above, the lifting device 40, clamp device 110 and the lifting method were described with respect to the lifting of a cross-arm 8,10. However, embodiments of he invention may also be applied in the lifting of other objects to the top of a pole, for example switch gear (comprising circuit breakers etc) or transformers.

In the embodiment above, the rope 150 is passed over the roller means 60 of the lifting device 40 at the top of the pole, beneath the guide member 122 of the clamp device 110 on the cross-arm to be lifted and back to the top of the pole where it is tied to an attachment arrangement 61 of the lifting device 40. This rope configuration reduces the effective weight to be lifted.

Other rope configurations may be adopted to provide further effective weight reductions.

The majority of components of the lifting device 40 and clamp device 110 are described above as being made of aluminium. As an alternative, different types of steel could be employed.

In the embodiment above, the cable retaining portion 46 of the lifting device 40 comprises support plates 68, a pin 70 connected between the support plates 68, and a removable peg 72. However, any arrangement whereby the wires 16 can be retained is suitable. For example, a cable retaining portion comprising four plastic rollers forming the sides of a rectangle could be used. The rectangle is openable so that the wires 16 can be guided therethrough and retained.

The frame portion 42 in the embodiment above comprises a first part 48 and a second part 50. The first part 48 and second part 50 are rigidly connected to each other to provide the frame portion 42 with a substantially L shaped configuration. As a modification, an arrangement could be provided whereby the first part 48 and the second part 50 could be locked at different angles with respect to each other. Such an arrangement would facilitate use of the lifting device 40 on poles having uneven tops.

To lift an object to the top of a pole, it is not necessary to use the clamp device 110; instead of tying one end of the rope 150 to an attachment arrangement 61, the end of the rope would be tied directly to the crossarm 8,10 to be lifted by attaching it, for example, using the hole 9 or one of the support pins 11.

Further, in lifting and lowering cross-arms 8,10, the rope 150 may be controlled manually or using other means, for example, a winch.

Finally, for reasons of safety, it is desirable that lifting and lowering operations can be performed by an operator situated a safe distance from the foot of the pole (thereby avoiding accidents should anything fall from the pole). A typical safe distance is considered to be a minimum of approximately 4m. A first way achieving the necessary safety clearance is for an operator to stand at the safe distance from the foot of the pole and to controllably pull or release the rope, or to operate the winch, as previously described. Such a method can, however, have the disadvantage that for certain resulting rope angles a force is exerted on the lifting device 40 which is mounted at the top of the pole such that this mounting could become loosened, or in exceptional circumstances, actually come free.

Accordingly, in second and third methods of achieving the safety distance, means are used to change the angle between the rope 150 and the lifting device 40. The second and third methods are shown in Fig. 10.

In the first method, an eye-bracket 200 is fixed at or near the base of the pole 4, and the rope 150 is passed through the eye. Lifting and lowering operations are then performed as described previously by an operator situated a safe distance from the pole 4.

In a second method, an eye-bracket 210 is attached to the ground, and the rope 150 is passed through the eye. The eye 210 may be attached to the ground by a spike arrangement (not shown) which is configured to ensure that the eye does not become detached from the ground during a lifting or lowering operation. Using this third method, the angle between the rope 150 and the lifting device 40 may be set as required, by selecting the position on the ground at which the eye-bracket 210 is attached. The lifting or lowering operation is then performed as described previously (with or without a winch) by an operator situated at a safe distance from the foot of the pole 4.

It will be appreciated that the present disclosure includes devices and methods suitable for lifting objects only, and those suitable for lowering objects only, in addition to those suitable for both purposes.

Claims

CLAIMS:

1. A device for use in lifting and/or lowering objects up or down a pole, the device comprising: frame means for mounting the device on a pole; and guide means supported on the frame means and oriented transversely of the device such that a rope can pass over the guide means and up and down two opposite sides of the pole, while both of said sides are effectively unobstructed by the frame means of the device.

2. A device for use in mounting and/or demounting objects on a pole constructed such that objects can be mounted on first and second opposing faces of the pole, while the device is positioned against a different, third face of the pole.

3. A device according to claim 1 or claim 2 having a substantially L-shaped frame means.

4. A device according to claim 3, wherein said frame means is configured to locate said device on the pole in a position such that force exerted on the device during a lifting or lowering operation is directed substantially down through the centre of the pole.

5. A device according to any preceding claim, further comprising fixing means for removably attaching the device to a pole.

6. A device according to claim 3 or 4 further comprising fixing means for removably attaching the device to a pole, wherein said fixing means comprises one or more straps for wrapping around the pole to hold a leg portion of said L-shaped frame means against the pole.

7. A device according to any preceding claim, comprising first and second roller means for guiding a rope.

8. A device according to claim 7, wherein said device is adapted to support said first and second roller means at a predetermined height above the top of the pole.

9. A device according to claim 7 or claim 8, wherein said device is adapted to support said first and second roller means at a horizontal distance apart such that, in use, a rope depending from the respective roller means hangs clear of the respective faces of the pole.

10. A device according to any preceding claim, further comprising attachment means for attaching a rope thereto.

11. A device according to claim 10, wherein said attachment means is pivotable to accommodate different rope angles.

12. A device according to claim 10 or claim 11, wherein said attachment means comprises a U-shaped member rotatable about a bolt.

13. A device according to any preceding claim, further comprising cable-retaining means.

14. A device according to claim 13, wherein said cable-retaining means is, in use, the uppermost part of the device.

15. A device according to any preceding claim for use in the raising and/or lowering of cross-arms used for supporting electricity and/or telephone cables.

16. A device substantially as described herein with reference to any of Figs. 3A, 3B, 4 and 9 of the accompanying drawings.

17. A method of raising (or lowering) an object up (down) a pole comprising the steps: providing a device as claimed in any one of claims 1 to 16 at the top of the pole; fixing a rope to the object to be raised (lowered); passing said rope over said device at the top of the pole; and controllably pulling (releasing) the rope, thereby to effect raising (lowering) of said object.

18. A method according to claim 17, further comprising the step of providing a clamp device on the object to be raised (lowered), the clamp device having means for attaching a rope thereto, and the step of fixing a rope to the object to be raised (lowered) being effected by attaching the rope to said clamp device.

19. A method of raising (or lowering) an object up (down) a pole comprising the steps: providing a device as claimed in any one of claims 1 to 16 at the top of the pole; fixing a rope to a given location; passing said rope around a part of the object to be raised (lowered) and over said device at the top of the pole in a configuration which provides mechanical advantage; and controllably pulling (releasing) the rope, thereby to effect raising (lowering) of said object.

20. A method of raising (or lowering) an object up (down) a pole comprising the steps: providing a device as claimed in any one of claims 1 to 16 at the top of the pole; fixing a rope at or near the top of the pole; passing said rope around a part of the object to be raised (lowered); passing said rope over said device at the top of the pole; and controllably pulling (releasing) the rope, thereby to effect raising (lowering) of said object.

21. A method according to claim 19 or claim 20, further comprising the step of providing a clamp device on the object to be raised (lowered), the clamp device having a low-friction guide means for retaining and guiding a rope passed therearound, and the step of passing said rope around a part of the object to be raised (lowered) being effected by passing the rope around the guide means of the clamp device.

22. A method as substantially described herein with reference to any of Figs. 1 to 9 of the accompanying drawings.

23. A clamp device for use in a method according to claim 18, comprising a central attachment point for a rope and means for gripping the object to be raised (lowered) at a plurality of spaced-apart points.

24. A clamp device for use in a method according to claim 21, comprising a low-friction guide for retaining and guiding rope passed therearound and means for gripping the object to be raised (lowered) at a plurality of spaced-apart points.

25. A clamp device according to claim 23 or claim 24, comprising locating surfaces for locating the object to be raised (lowered) at a predetermined orientation to the clamp device.

26. A clamp device according to claim 25, wherein said means for gripping the object to be raised (lowered) comprise screw means mounted at a predetermined angle with respect to said locating surfaces.

27. A clamp device according to claim 26, wherein each respective screw means has a formed head.

28. A clamp device according to any one of claims 23 to 27 adapted to allow easy insertion (extraction) of a mounting-bolt into (from) the object to be raised (lowered) when the clamp device is attached.

29. A clamp device according to claim 28, wherein the distance between adjacent spaced-apart points is sufficient to allow said mounting-bolt to be passed therebetween.

30. A clamp device for use in the raising (lowering) of a cross-arm used to support electricity and/or telephone cables up (down) a pole comprising: a central attachment point for a rope; locating surfaces for locating the cross-arm to be raised (lowered) at a predetermined orientation to the clamp device; and gripping means arranged at a predetermined angle to said locating surfaces for gripping the cross-arm to be raised (lowered) at a plurality of spaced-apart points, the distance between adjacent spaced-apart points being sufficient to allow a cross-arm-mounting-bolt to be passed therebetween.

31. A clamp device for use in the raising (or lowering) of a cross-arm used to support electricity and/or telephone cables up (down) a pole comprising: a low-friction guide for retaining and guiding a rope passed therearound; locating surfaces for locating the cross-arm to be raised (lowered) at a predetermined orientation to the clamp device; and gripping means arranged at a predetermined angle to said locating surfaces for gripping the cross-arm to be raised/lowered at a plurality of spaced-apart points, the distance between adjacent spaced-apart points being sufficient to allow a cross-arm-mounting-bolt to be passed therebetween.

32. A clamp device substantially as described herein with reference to Figs. 5, 6 and 7 of the accompanying drawings.

33. A method of raising (or lowering) a cross-arm used to support electricity and/or telephone cables up (down) a pole, comprising the steps: attaching a clamp device as claimed in claim 30 to the cross-arm to be raised (lowered); attaching a rope to said clamp device; providing rope guide means at the top of the pole; passing said rope over said rope guide means; and controllably pulling (releasing) said rope, thereby to effect raising (lowering) of said cross-arm.

34. A method of raising (or lowering) a cross-arm used to support electricity and/or telephone cables up (down) a pole, comprising the steps: attaching a clamp device as claimed in claim 31 or claim 32 to the cross-arm to be raised (lowered); providing rope guide means at the top of the pole; fixing a rope to a given location; passing said rope around the guide means of the clamp device and over said rope guide means at the top of the pole in a configuration which provides mechanical advantage; and controllably pulling (releasing) the rope, thereby to effect raising (lowering) of said cross-arm.

35. A method of raising (or lowering) a cross-arm used to support electricity and/or telephone cables up (down) a pole comprising the steps: attaching a clamp device as claimed in claim 31 or claim 32 to the cross-arm to be raised (lowered); providing rope guide means at the top of the pole; fixing a rope at or near the tope of the pole; passing said rope around the guide means of said clamp device; passing said rope over said rope guide means; and controllably pulling (releasing) the rope, thereby to effect raising (lowering) of said cross-arm.