The present invention is based on a crane arrangement for moving goods such as logs. It comprises a base that can be fitted to a carrier or surface such as a truck bed. Via, for example, a central unit, said base can have a fixed or a freely mobile connection to one end of a tillable arm. At its other end, this arm has an articulated connection with a number of arms (most suitably two). The free end of the outermost of these other arms is intended to interface and work with crane-tip equipment that is used for moving goods. In moving goods, the tiltable arm and the arms connected thereto are operated on by devices that regulate the arms' individual positions in relation to each other. Cranes of such a type are already known and have the advantage of increased reach without significantly increased weight. They also provide increased mobility at close range and, finally, superior "folding" when the crane is not to be used (e.g. the vehicle is to be used for transport). In the present case, the idea is that all the movements the arms are asked to make are accomplished using hydraulic cylinders. Of course, it would also be possible to use other devices that have the same properties. In the present case, the idea is that one of the hydraulic cylinders is to be a lifting cylinder. It has been shown that, with known cranes, the lifting cylinder's torque arm "shortens" depending on mast inclination.

The purpose of the present invention is that it should provide a lifting arrangement which is so designed that the lifting cylinder's torque arm is not affected by mast inclination. This is achieved by placing the lifting cylinder parallel to the mast arm, locating the cylinder's bearing point close to that of the mast arm and connecting the other end of the hydraulic cylinder to a linkage system which is so arranged that the torque arm for the lifting cylinder remains constant. The linkage system comprises two arm units. One of these is connected halfway between the other's two ends. One of the two ends of this latter arm unit is connected to the upper end of the lifting cylinder. The other is connected to the end of the two lifting arms that are connected to the upper end of the tiltable mast. The remaining end of the other arm unit is connected to the upper end of the mast arm.

The outermost arm of the lifting arm system connected to the tiltable mast can be

replaced by a telescopic unit comprising two hollow (tubular) parts (one of which can slide inside the other), each of which is acted on by its own cylinder. One of these cylinders is dedicated to extending the telescope and the other to retracting it. One great advantage of the present lifting arrangement is that all the hydraulic fluid lines can be located in the arrangement's arms. It is presumably clear that the telescopic arm can also be used in systems other than the present crane arrangement.

It should also presumably be obvious that the pivot axle for the lower end of the tiltable mast and the pivot axle for the lower end of the lifting cylinder can be parallel with each other or placed at an angle of 20 to 35 degrees to each other.

An operator's seat or cage can also be attached to the crane arrangement's base. Via a linkage system, this observation seat/cage can be lowered/raised/turned so that the operator retains a good view over the working area. This "viewing arrangement" can also be used in applications other than the present crane arrangement.

The described crane arrangement can be exploited in various work situations. For example, it can be located at one end of a truck or on a vessel or on a building site. Other applications should not be difficult to find.

The following patent claims reiterate the characteristic particularities of the present invention.

One possible design of the present invention is described with the assistance of the attached 16 figures.

Figure 1 shows a tiltable crane.

Figure 2 shows how the tilting capability can manoeuvre the crane in figure 1 into different positions.

Figure 3 shows a viewing platform for the operator of the crane arrangement in figure 1.

Figure 4 shows an alternative design of the outer boom (D) in figure 1. In this design, the outer boom has two hydraulic cylinders. One of these is dedicated to extending the outer boom and the other to retracting it.

Figure 5 shows a cross section of the hydraulic cylinder that extends the outer boom shown in figure 3.

Figure 6 shows a cut-away of the hydraulic cylinder that retracts the outer boom shown in figure 4.

Figure 7 shows a complete crane arrangement with an operator station and a telescopic outer boom. Figure 8 shows a crane arrangement equipped truck that is picking up goods.

Figure 9 shows a crane arrangement delivering the picked up goods.

Figure 10 shows the crane arrangement in one "folded away/rest" position. The truck can now transport the load.

Figure 11 shows a crane arrangement in another rest position. Figure 12 shows a viewing platform for the operator of the crane arrangement.

Figure 13 shows an extending cylinder for a hoseless telescopic boom.

Figure 14 shows a retracting cylinder for a hoseless telescopic boom.

Figure 15 shows a schematic cut-away of a telescopic boom.

Figure 16 shows an alternative design of tilt cylinder G.

Figure 1 shows only one possible crane arrangement as per the present invention.

The crane arrangement has a base (P) that can be located on, for example, a truck bed, a vessel or any other suitable carrier/surface whatsoever. At the top of base P, there is a central unit (A) that, using known means, can rotate around said base. The central unit has two mounting lugs between which a pivot axle (1 ) for one end of a tiltable arm (B) is fitted. Arm B can also be referred to as a crane mast. Via an axle (4), crane mast B is connected to lifting arm C. At its other end, this latter arm has an axle (9) that provides an articulated joint to an outer boom

(D). The relative positions of lifting arm C and outer boom D are regulated via a hydraulic cylinder (J). This is connected to arm C via axle 10 and to boom D by axle 11. At central unit A, there is a second axle (2) that provides a pivot for one end of a hydraulic cylinder (G). The latter has its other end attached, via an axle

(3), to tiltable arm B. Hydraulic cylinder G can also be referred to as a tilt cylinder.

It regulates the position of tiltable arm B. Axle 2 also provides the bearing for one end of a lifting cylinder (H). The other end of this has axle 7 as its bearing in a linkage system (E) that comprises two units. The unit to which lifting cylinder H is connected at one end is connected, via axle 6, to lifting arm C. Via axle 8, the second unit in the linkage system is connected at one end to the same unit as that to which lifting cylinder H is attached. Via axle 5, the other end of the second unit is connected to tilt arm B. Thanks to said linkage system E, the lifting arrangement will only be acted on by lifting cylinder H and then only with a constant lever that never changes. At its outer end, outer boom D has mounting lugs for the attachment of crane-end equipment (often a grab claw).

Figure 2 shows the crane arrangement with tiltable arm B and the connected C and D arms in various positions.

A viewing platform for the operator of the crane arrangement can also be connected to base P. The viewing platform has a linkage system (K, L, N and O) in which the links have axles 12 - 17 as their bearings. The links are acted on by hydraulic cylinder M.

Outer boom D in figure 1 can be replaced by a telescopic arm comprising two hollow parts (18 and 19) that are displaceable one inside the other and which can have any suitable cross section whatsoever. The telescopic outer boom can be extended to double its length and also retracted to half its length. To achieve these length changes, the telescopic outer boom has two hydraulic cylinders, 20 and 21. Of these, 20 is dedicated to extending the inner telescopic component (19). Cylinder 21 is dedicated to retracting the extended, telescopic, outer boom. The telescopic outer boom can, of course, be of any design whatsoever. Figures 5 and 6 show longitudinal sections of the two hydraulic cylinders that bring about the extension and retraction of the moving component in the telescopic outer boom. Both hydraulic cylinders each have one of their ends attached to the inner end of the outer part of the telescopic outer boom. The other ends of the hydraulic cylinders are attached to the front end of the extendable part of the telescopic outer boom. A look at the hydraulic cylinder in figure 5 shows that there is a

positive chamber for oil and a negative chamber for oil. Oil delivery into the hydraulic cylinder has been labelled 32 and oil leaving the hydraulic cylinder has been labelled 34. Mobile piston 23 has piston seals (25) and support rings (26).

Vent holes (30) are provided for oil removal. Both 27 and 24 are seals in end sleeve 22. The item labelled 29 is a connector. To aid comprehension, the figure has been coloured - blue shows delivery oil and red shows return oil. The hydraulic cylinder in figure 6 works in the same way as that in figure 5, but in the opposite direction. The delivery oil (35) returns the mobile piston (38) to its start position. Return oil has been labelled 36 and coloured red (delivery oil is blue). The mounting of the piston (38) to the inner mobile part of the telescopic outer boom is labelled 37.

Figure 7 shows a crane arrangement equipped with both a telescopic outer boom and a viewing platform for the operator of the crane arrangement. Figure 8 shows a truck (40), truck bed (41) and timber (42). The truck has a crane arrangement as per figure 7 and is shown in the position for picking up goods for loading onto the truck bed. Figure 9 shows the crane arrangement after delivering the goods to the truck. Figure 10 shows a fully loaded truck with the crane arrangement brought to a rest position where it occupies as little space as possible and presents as little obstacle to travel as possible.

Figure 11 shows a fully loaded truck with the crane arrangement in a different rest position that also presents no obstacles for transporting the load.

Figures 13 to 15 show details of a telescopic crane arm with hoseless transmission of hydrodynamics to crane-tip equipment.

Figure 13 shows a schematic cut-away of an extending cylinder with an active positive chamber and pressure/flow compensated flow channel (black arrows).

When oil is pumped into the positive chamber, the piston is forced outwards and pushes the telescopic boom outwards. In turn, this pulls out the retracting cylinder. This increases the volume of the flow channel at the same rate as it decreases that of the negative chamber. If the cross section of the negative chamber is exactly the same as that of the flow channel, and they are both in open communication (small black arrows), the pressure and volume velocity in the flow channel will not be influenced by, or influence, the telescopic movement.

Figure 14 shows a schematic cut-away of a retracting cylinder with an active negative chamber and an open central channel for the free flow of return oil (white arrows). When oil is pumped into the negative chamber, the cylinder retracts, pulling the telescopic boom with it. In its turn, this compresses the extending cylinder. The volume change in the central channel is completely equal when it is open to the tank.

Figure 15 shows a compilation cut-away schematic of a telescopic boom. It reveals the relative positions of the cylinders and the hydraulic connections to the pump, directional control valve and tank.

The placing of the extending cylinder in the bottom of the telescope and the contracting cylinder in its top counteracts the "bureau drawer effect" (jamming).

Figure 16 shows an alternative design of tilt cylinder G and its mounting. In this case, body A has lugs for three horizontal axles. The third is behind and somewhat higher than mast axle 1 and constitutes the new lower mounting for tilt cylinder G. The upper mounting of this latter has been moved to the "reverse side" of mast B.

Tilt cylinder G thus acquires a retracting function. To increase the active area during "braking" and "starting", it has also been given an extra piston.

An ordinary hydraulic cylinder (1 ) has been given a bi-symmetrical guide block designed to enable the connection of a short cylinder (3). There is a normal guide block (4) at the other end of cylinder 3. A piston (5) with integrated guide sleeve

runs inside short cylinder 3. The length of this guide sleeve is slightly greater than the short cylinder's stroke length plus the inner length of guide block 2.

The guide sleeve's bore is 4 - 7% larger than the diameter of the piston stem. Cylinder chamber 7's sole connection with cylinder chamber 6 is through this gap.

Cylinder chamber 8 is drained through channel 9 and non-return valve 10 for port B. The resultant vacuum helps to maintain piston 5 in position. Cylinder chamber 6 is connected to port A via channel 11. Running in this channel, "braking cone" 12 is partly controlled by the oil flow and partly by pistons 5 and 13.

As shown by the preceding, a crane arrangement that is extremely simple to apply in various work situations has been developed. Furthermore, by putting the present invention's crane arrangement on a base, said arrangement can be deployed wherever it is needed.

The development of a crane arrangement that works with a more or less constant lever has the great advantage that it is no longer necessary to take the problem of lever changes into account. In various work situations, this leaves the correct dimensioning (to match loading) of lifting arms and outer booms as the sole main criterion.