TECHNICAL FIELD

The present invention relates to a device to be used for climbing poles, a so-called pole climber. More particularly, the invention relates to the design of a light pole climber of composite material.

BACKGROUND ART

When climbing poles there are used pole climbers which are fastened to the feet. Usually, these pole climbers are made of steel and consist of a foot plate connected to some form of gripping arm. The embodiment results in the occurrence of unfavourable bending stresses when subjected to load. In addition, the connection between the gripping arm and the foot plate is loaded. Furthermore, pole climbers of steel are heavy and may unexpectedly break in spite of the fact that a visual inspection has not revealed any fault on the climber.

SUMMARY OF THE INVENTION

The present pole climber comprises a foot plate and a tension rod, one end of which constitutes a gripping member which grips around the pole and the other end of which constitutes a support for the foot plate. The tension rod is connected at an angle of α to the foot plate. The connection is made between that part of the tension rod which constitutes the support and that end of the foot plate which is located furthest away from the pole, i.e. the heel. The angle αbetween the tension rod and the foot plate in the vertical plane is usually 20-45 degrees, preferably 25- 35 degrees. From the point of view of stability, the foot plate and the tension rod are then linked together at the toe end of the foot plate. This connection is made such that the straight part of the tension rod forms an angle β,

usually 5-25 degrees, preferably 10-20 degrees, with the longitudinal axis of the foot plate in the horizontal plane.

The invention eliminates, in all essentials, the occurrence of bending stresses in the vertical plane of the tension rod, which joins the gripping member to the foot plate, while at the same time the connections between the foot plate and the tension rod are loaded to a minimum extent. Instead, the main part of the load is taken up as tensile stress in the tension rod and compressive load in the foot plate. This means that the material can be utilized to an optimum extent and hence a reliable pole climber with low weight is obtained, which, in addition, is fixed in a more reliable manner in case of increasing load; a self-locking function is obtained.

Since the tension rod is subjected substantially to tensile stress, it is advantageously designed of a fibre composite, for example sheet moulding compound (SMC) , a polyester resin with addition of glass fibres and fillers, with the fibres oriented in the direction of tension, or other fibre- reinforced thermosetting resin with directed fibres, suitably based on thermosetting resins sch as polyester resins or epoxy resins. By orienting the fibres in the composite material, a very reliable pole climber is obtained. The risk of sudden ruptures is eliminated or at least minimized since the fibres, also in case of an incipient rupture, may take up a great load in the damaged part. Glass, carbon or aramide fibres with a tensile strength of at least 1250 MPa are suitably used.

When the pole climber is made in one piece, the foot plate can be made in fibre-reinforced thermosetting resin of the same type as the tension rod. If the pole climber is made in two separate parts - tension rod and foot plate - the foot plate can also be made of thermoplastic resin, for example thermoplastic polyester with randomly oriented fibres.

With a pole climber formed and constructed in a material according to the invention, additional advantages obtained are greater stiffness than in light steel pole climbers available on the market, reduced corrosion problems than when using steel, and reduced production costs. This results in a reliable pole climber with low maintenance costs; no other security check than the visual inspection of the climber himself is required.

By providing the stud in the toe of the foot plate with a cylindrical cemented carbide pin with an acute angle of 60 degrees, it is ensured that the pole climber engages and releases easily. In addition, the wear of the toe portion is reduced.

When being made in two parts, the pole climber can also be adapted to different pole diameters by being provided with replaceable tension rods of different lengths.

BRIEF DESCRIPTION OF THE DRAWING

The invention is shown viewed from the side in Figure 1 and viewed from above in Figure 2. Figure 3 shows the forces when subjecting the pole climber to a load.

DESCRIPTION OF THE PREFERRED EMBODIMENT

According to the invention, the pole climber comprises a foot plate 11 and a tension rod 12, one end of which constitutes a gripping member 13 for gripping around the pole 10 and the other end of which constitutes a support for the foot plate 11 to which the tension rod 12 is connected. The foot plate 11 and the tension rod 12 are joined at an angle α, which is usually 20-45 degrees, especially 25-35 degrees. The connection is made between that end of the tension rod 12 which acts as support 14 for the foot plate 11 and the heel portion 15 of the foot plate 11.

For reasons of stability, the toe portion 16 of the foot plate 11 and the tension rod 12 are then connected together by means of the bar 18 so that the straight part of the tension rod 12 forms an angle β with the longitudinal axis of the foot plate 11. The angle β may vary within the interval 5-25 degrees, especially 10-20 degrees.

The tension rod 12 is made of fibre-reinforced composite material with the fibres directed in the longitudinal direction, suitably sheet moulding compound (SMC) , or other fibre-reinforced thermosetting resin based on ester resin or epoxy resin and reinforced with fibres, for example glass, carbon or aramide fibres, which have a tensile strength of at least 1250 MPa, oriented in the longitudinal direction. The gripping member 13 and the support 14 consist of the bent ends of the tension rod 12 and are made such that the tension rod 12 remains in one plane.

When ascending a pule 10, the gripping member 13, when being loaded, grips around the pole 10 while at the same time the toe portion 16 of the foot plate 11 is pressed against the pole 10 so that the pole climber engages the pole 10 in a safe grip. To ensure, during climbing, that the pole climber engages and releases its grip easily and to reduce the wear of the toe portion 16 of the foot plate 11, a stud 17 is mounted in the toe portion, which stud 17 makes an acute angle of 60 degrees and is provided with a cemented carbide pin.

By designing the pole climber with a tension rod 12 which is connected at an angle α to the foot plate 11 in the heel portion 15 thereof, as shown in Figure 3 the main part of the load F will be absorbed as tensile stress I in the tension rod 12. The foot plate 11 takes up the compressive load II. The upwardly-directed force III which may arise will be absorbed by the bar 18 and may be varied within an angle of 45 degrees.

By mounting the tension rod 12 and the foot plate 11 according to the above, the pole climber can be easily adapted to different pole diameters by making the tension rod 12 replaceable and providing it in several lengths for different pole diameters.