The present invention concerns a travelling crab as defined in the preamble to Claim 1.

In prior art is known, e.g. through the reference FI-74433, a travelling crab disposed to run in guidance by a guiding rail, for transporting a load connected to the travelling crab. The guiding rail comprises two rolling surfaces facing away from each other and located on sides of the guiding rail facing away from each other. The travelling crab comprises a body. A first wheel and a second wheel are rotatably carried on the body in such manner that their axes of rotation are parallel and spaced from each other transversely in relation to the longitudinal direction of the guiding rail. The wheels are disposed on different sides of the guiding rail so that the guiding rail is located between the wheels and the wheels are in traction contact with the rolling surfaces, in register with each other on different sides of the guiding rail. The travelling grab also comprises a traction motor, connected to the body and arranged to drive the wheels.

A particular application in which travelling crabs of this kind are used is in connection with maintenance of real estate, where the transport system is employed to suspend movable service platforms, hanging cages, hanging ladders, etc. Using such ancillary equipment, one can maintain and service outside and inside facades of buildings, inside and outside roof surfaces, e.g. wash roof coverings of glass, install facade elements, replace broken windows, etc. The guiding rail in support of which the travelling crab runs with the equipment thereto attached, may be installed to run the hole circuit of the building's facade, by making it curve at corners to conform to the configuration of the building. When

the point of application arising from the weight of the load is located beside the wheels and rail, the guiding rail may equally differ from the horizontal to be directed upward or downward at an inclination, or vertical, and the travelling crab provided with drive and brake means can negotiate uphill and downhill stretches thus formed, and also move vertically, along the guiding rail.

The guiding rail may present deformities, which are due to dimensional errors of the guiding rail. The guiding rail has usually been shaped to be an elongated track, out of rail sections joined to each other end to end, whereby discontinuities may occur at the junctions for the reason that the ends of the guiding rail sections placed end to end are not precisely aligned. In view of such deformities and discontinuities the means of prior art has been endowed with a characteristic of resiliency in that one wheel has been divided in two, perpendicularly in relation to the axis of rotation, to constitute two wheel parts which are urged towards each other by a spring. As a consequence the travelling crab can run flexibly past such problematic points. By the elastic arrangement also a suitable pre-tensioning force between the wheels and against the guiding rail is obtained so that the travelling crab is enabled to run along the guiding rail also under small load. In the absence of pre-tensioning, slipping might take place between wheels and rail. The problem in the travelling crab of prior art is that adjustment of the pre-tension force is exceedingly cumbersome because the spring adjusting mechanism is very badly accessible and is located on that side of the means on which the rail is usually fixed to the wall. In addition, a split wheel affords only minimal range of adjustment and elastic accom¬ modation, whereby the travelling crab is only approp-

riate in the case of guiding rail deformities of rather limited magnitude. Moreover, owing to the minimal elastic clearance, the travelling crab is restricted to be used in connection with one kind of guiding rail only, and it cannot be readily adjusted for use with a larger or smaller guiding rail. The travelling crab of prior art is complex in its construction and comprises numerous components; for instance, the wheels are different from each other. It is thus understood that the means of prior art comprises a lot of parts which are subject to wear and have to be replaced.

The object of the invention is to eliminate the drawbacks discussed above. The object of the invention is specifically to disclose a travelling crab which presents a simple construction, containing few parts which are subject to wear and have to be replaced, and in which the mechanism producing the pre-tension force is easy to adjust.

It is moreover an object of the invention to disclose a travelling crab which is able without disturbance of its running to pass over major deformities in the guiding rail. Still one object of the invention is to disclose a travelling crab in which the spacing of the wheels can be adjusted with ease so that the travelling crab can be used on several guiding rails with different dimensions. The travelling crab of the invention is characterized by that which is stated in Claim 1.

As taught by the invention, the body comprises a first body part, to which a first wheel is connected, and a second body part, to which a second wheel is connected. The first body part and second body part are swivellably joined by a hinge, the swivelling axis defined by the hinge parallelling the

axes of rotation of the wheels and located between said axes of rotation at a distance from the plane passing through the axes of rotation. The travelling crab comprises a spring means, connected between the first body part and the second body part, to swivel the body parts around the axis of rotation of the hinge for urging the wheels elastically against the guiding rail.

The advantage afforded by the invention is that as the body is divided into two body parts a simple construction is achieved so that it contains few components subject to wear and needing replacement, and the spring means mechanism producing the pre-tensioning force is easy to adjust. A further advantage of the invention is that the travelling crab is able without interference with its running to pass major deformities in the guiding rail. An advantage of the invention is furthermore that the distance between wheels can be adjusted with ease so that the travelling crab is usable on several guiding rails with different dimensions.

In an advantageous embodiment of the travelling crab, the first body part comprises a first swivelling arm, and the second body part comprises a second swivelling arm. The swivelling arms extend to a distance from the plane passing through the axes of rotation of the wheels (from the plane at right angles against the longitudinal direction of the guiding rail) on its opposite side relative to the hinge. A spring means has been provided to act between the swivelling arms, to urge the swivelling arms against each other in order to press the wheels against the rolling surfaces of the guiding rail.

In an advantageous embodiment of the travelling crab, the travelling crab comprises a first pin, rotatably carried in the first swivelling arm, and a second pin, rotatably carried in the second

swivelling arm. To the pins belong mutually aligning, transversely piercing holes. The spring means comprises a rod, such as a bolt or equivalent, piercingly disposed in said holes. The rod carries on its end a first counter-member, such as a nut or bolt head, for bracing the rod against one pin, and the other end of the rod carries a second counter-member, such as a nut or bolt head. The spring means further comprises a compression spring, disposed between the second counter-member and the first pin. A spring means of this type is quite easy to adjust because it is readily accessible.

In an advantageous embodiment of the travelling crab, the swivelling arms are fork-shaped and comprise two side-by-side legs, the pins being disposed between these.

In an advantageous embodiment of the travelling crab, the first and second pins present piercing, aligned second holes, and the adjusting means comprises an adjustment rod, such as a threaded bolt or the like, disposed in these holes, passing through them. The adjusting means further comprises an adjustment member, such as a nut or the like, cooperating with the adjustment rod, whereby the turning angle of the swivelling arms can be limited by placing the adjustment member in desired position on the adjustment rod. This adjustment is quite easy to carry out because the adjusting means is readily accessible. In an advantageous embodiment of the travelling crab, the travelling crab comprises a first traction motor, connected to the first body part and disposed to drive the first wheel, and a second traction motor, connected to the second body part and disposed to drive the second wheel. When each wheel is driven by a traction motor of its own, the travelling crab will traverse without hindrance any bends which

have been made in the guiding rail. It is well known that while going through a bend one wheel tends to run faster than the other. Provision of two traction motors allows a differential speed between wheels. If both wheels are driven by one traction motor, it is very hard to avoid one or the other wheel from slipping in bends.

In the following the invention is described in detail, referring to the attached drawing, wherein Fig. 1 presents an embodiment of the travelling crab of the invention, in cooperation with the guiding rail, the travelling crab being partially sectioned,

Fig. 2 shows the travelling crab of Fig. 1 as viewed in the direction II-II,

Fig. 3 shows the travelling crab of Fig. 1 as viewed in the direction III-III, and

Fig. 4 presents the section IV-IV from Fig. 2. In Figs 1-3 is seen a travelling crab 1, intended to be used in cooperation with a guiding rail 2, in support and guidance of which the travelling crab runs. The guiding rail 2 is seen in Fig. 1 as a sectional profile. The load, indicated by an arrow F, is so suspended from the travelling crab 1 that the point of application of its weight is located beside the wheels 6,7 of the travelling crab and beside the guiding rail 2, whereby the phenomenon well-known from apparatus of this type is achieved, namely, that the load increases the compressive force between the wheels 6,7 and the guiding rail, and the friction force, so that the travelling crab is enabled to run also along a guiding rail placed in inclined and vertical position. The guiding rail 2 has two rolling surfaces

3,4 facing away from each other, located on sides of the guiding rail facing away from each other. In the

embodiment of the figures the rolling surfaces 3,4, and similarly the shapes of the wheels 6,7 have been disposed to cause tangential, punctiform contacts between the rolling surfaces and wheels. The rolling surface of the guiding rail is convexly round, and the wheels present two conical surfaces, at an angle in relation to each other, as contact surfaces against the convex rolling surface of the guiding rail.

The travelling crab 1 further has a body 5. The first wheel 6 and second wheel 7 have been rotatably carried in the body 5 so that their axes of rotation 8,9 are parallel and spaced from each other transversely in relation to the longitudinal direction of the guiding rail. The wheels 6,7 are located on different sides of the guiding rail 2 so that the guiding rail is located between the wheels, and the wheels are in traction contact with the rolling surfaces, substantially in register on different sides of the guiding rail. To drive the wheels 6,7, a specific traction motor 10,11 has been provided for each, e.g. an electric motor, which by an angle gear drives a shaft to which the respective wheel has been connected.

The body 5 has been divided into two parts: the first body part 5 ¹ , to which the first wheel 6 and the first traction motor 10 driving it, with its angle gear, have been connected, and the second body part 5 ² , to which the second wheel 7 and the second traction motor 11 driving it, with its angle gear, have been connected. The first body part 5 ¹ and the second body part 5 ² are swivellably joined by a hinge 12. The hinge joint 12 defines a swivelling axis, parallelling the axes of rotation 8,9 of the wheels 6,7 and located between the axes of rotation of the wheels at a distance 1 from the plane T passing through the axes of rotation. The travelling crab 1 further comprises a spring means 13, connected between the first body part

5 ¹ and the second body part 5 ² in such manner that the body parts are continuously forced to turn about the axis of rotation of the hinge joint 12 so that the wheels 6,7 will press elastically against the guiding rail 2.

The first body part 5 ¹ comprises a first swivelling arm 15 and the second body part 5 ² comprises a second swivelling arm 16. The swivelling arms 15,16 extend to a distance from the plane T passing through the axes of rotation 8,9 of the wheels 6,7, on the opposite side in relation to the hinge 12. Said spring means 13 acts in such manner between the swivelling arms 15,16 that the swivelling arms are constantly urged against each other, whereby the wheels 5,6 press from different sides of the guiding rail 2 against its rolling surfaces.

Fig. 4 shows the design of the spring means 13 and the adjusting means 14, in the present exemplary embodiment. The spring means 13 has been disposed so that the first pin 17 is rotatably carried on the first swivelling arm 15 and the second pin 18 is rotatably carried on the second swivelling arm 16. The swivelling arms 15,16 are fork-shaped and comprise two side-by-side legs, between which the pins 17,18 are disposed. The pins 17 and 18 present aligned, transversely piercing holes 19,20. The rod 21 of the spring means 13, in this case a bolt, has been disposed to pass through the holes 19,20. The bolt 21 carries on its end the first counter-member 22, which is a nut, for bracing the bolt against the second pin 18, and on the other end of the bolt is provided a second counter-member 23, that is the bolt head. A compression spring 22, in this case a pile of cup springs, has been provided between the bolt head 23 and the first pin 17. The tension of the spring assembly can be adjusted by means of the nut.

As can be seen from Fig. 4, the adjusting means 14 limits the rotation in relation to each other of the body parts 5 ¹ , 5 ² , i.e. of the swivelling arms 15 and 16. The adjusting means 14 has here been implemented in such manner that the first and second pins 17,18 comprise piercing, aligned second holes 25,26. The adjusting means 14 comprises an adjustment rod 27, such as a threaded bolt or the like, piercingly disposed in the holes 25,26, and an adjustment member 28, such as a nut or the like, cooperating with the adjustment rod 27, whereby the swivelling away from each other of the swivelling arms 15,16 can be limited by positioning the nut 28 as desired on the adjustment rod. The invention is not exclusively delimited to concern the embodiment examples presented in the foregoing: numerous modifications are feasible within the scope of the inventive idea defined by the claims.