GB2210004A

GB2210004A - Locking device for wheel axles of mobile cranes

Info

Publication number: GB2210004A
Application number: GB8829451A
Authority: GB
Inventors: Horst Bendix; Bernd Hellmich; Juergen Neumann; Hartmut Scheel
Original assignee: MAN Takraf Fordertechnik GmbH
Current assignee: Takraf GmbH
Priority date: 1987-12-18
Filing date: 1988-12-16
Publication date: 1989-06-01
Anticipated expiration: 2008-12-16
Also published as: GB8829451D0; DE3833247A1; DD281084A7; GB2210004B

Description

2 12 1 61 U 61 J 1 j 111 LOCKING DEVICE FOR WHEEL AXLES OF MOBILE CRANES

The invention relates to locking devices for wheel axles of mobile cranes particularly though not exclusively railway cranes, in the operative position of which it is necessary to provide for a reduction in or elimation of the spring movement in the running gear for reasons of stability.

Constructions are known which mechanically eliminate such spring movement.

A disadvantage with such constructions is that, because of the rigid connection between the wheel axle and the vehicle chassis and the resulting absence of possible methods of compensation or equalisation, they are only suitable for double-axle vehicles or bogies.

A further disadvantage lies in the operational safety which is dependent on the state of wear.

Information sources: WP 87, 332, IPC B 61 F; 5/24 WP 104 478, IPC B 61 F; 5/50 WP No 157 858 IPC B 61 F; 5/38 discloses a further construction which, for the purposes of eliminating spring movements, has a pressure fluid cylinder arranged between a vehicle frame structure and a transverse compensating member which connects a respective pair of wheel axles. In that arrangement there is the disadvantage that in the operative position of the arrangement, particularly in relation to railway cranes, that transverse compensating member must be designed to carry high loadings. On the other hand thepressure fluid cylinder is constantly loaded in the travel mode by virtue of its fixed pivotal connection and thereby suffers from a high rate of wear.

West German Patent Specification No 2 800 048 IPC B 61 F; 5/50 discloses a further construction in which pressure fluid cylinders are fixedly connected to the respective wheel axles. The disadvantage of that arrangement also lies in the constant loading applied to the cylinder and the pivotal mounting thereof in the travel mode.

West German Patent Specification No 2 711 174 IPC B 61 F; 5/00 discloses a spring locking device which avoids these disadvantages insofar as it moves the working cylinders towards the spring means when required in such a way that the spring movement'is entirely eleminated. However, there is a lack of wheel load compensation when the crane is travelling.

i The invention seeks to provide a locking device for wheel axles of mobile cranes, in particular railway cranes, which permits them to be operated with stability and without derailment.

The invention is based on the problem of developing a locking device for wheel axles by arrangement of per se known means, which in the operative position of the crane prevents overloading of the vehicle springing, which in that connection permits wheel load compensation which is necessary for derail ment-proof travel over track irregularities and which contributes to enhancing stability by virtue of incorporation of the inherent weights of the wheel sets into the central ballast.

A pressure fluid cylinder is arranged between the chassis frame and each axle bearing of a wheel axle, wherein all cylinders of a respective side of the vehicle are so interconnected as to provide for equalisation of the pressure fluid.

In accordance with the invention, the pressure fluid cylinders are retracted in the transportation position of the crane and all axle bearings and thus the wheel axles have sufficient play or movement relative to the vehicle frame.

In making the transfer from the transportation position to the mobile operating position, the pistons of the pressure fluid cylinders bear against the axle bearings in such a way that the action of the force approximately corresponds to the inherently loaded springing condition and causes the vertical suspension movement to be completely eliminated. By virtue of the hydraulic connection of the cylinders on the one hand and the suspension spring deflection movement which is still present, on the other hand, this therefore provides for derail ment-proof travel over tracks with track defects and distortions. Overloading of the springing system is avoided.

In order to enhance or ensure stability by virtue of incorporation of the inherent weights of the wheel axles into the central ballast, in the case of free-standing and non-negotiable load curves, the arrangement provides a further extension movement of the pistons and thus causes lifting of the entire crane until a condition of fixed abutment within the 3 v 1 3 cylinder is reached, thereby providing for total elimination of extension and retraction spring movement.

A limiting means is arranged to limit the distance between the vehicle chassis frame and the wheel bearings.

To prevent the piston from slipping down in the transportation position of the crane, spring-loaded balls may be provided which engage into a groove at the upper end of the piston.

An embodiment of the invention is illustrated in the drawing in which:

Figure 1 is a view of the arrangement of a locking device mounted on a chassis frame or bogie of a railway crane, Figure 2 is a view in section taken along line A-A in Figure 1, showing the transportation position, Figure 3 is a view in section taken along line A-A in Figure 1, showing the mobile operating position, Figure 4 is a view in section taken along line A-A in Figure 1, showing the completely locked operating position, and Figure 5 is a view in section taken along line B-B in Figure 2 through the piston locking arrangement.

In a chassis frame 1, as shown in Figures 1 and 2, associated with each wheel axle 2 with its axle bearings 3 are two pressure fluid (hydraulic liquid-operated) cylinders 4. All the pressure fluid cylinders 4 at one side of the chassis frame are hydraulically interconnected. The axle bearings 3 are connected to the chassis frame 1 by a limiting means 5 in such a way that there is a play sl (see Figure 2) between the chassis frame 1 and the limiting means 5, in the transportation condition of the crane.

At the same time there is a further play s2 between the axle bearing 3 and the piston 6 of the pressure fluid cylinder 4, wherein generally sl,. / S2. To secure the piston position in the pressure-less condition, arranged in the upper part of the pressure fluid cylinder 4 are balls 8 which are loaded by springs 9 and which engage into a groove 7 on the piston 6, to retain the piston 6 (see Figure 5). In the freely movable 4 operating position of the crane the pressure fluid cylinder 4 is subjected to pressure in such a way that, due to the extension movement of the piston 6, the play S2 is certain to disappear, whereas the play sl is only immaterially reduced (see Figure 3). The extension of the piston 6 at the same time presses the balls 8 back into their guides 10. By virtue of the hydraulic connection of the pressure fluid cylinders 4 with each other, at each side of the chassis frame, the arrangement thus provides a wheel load compensation or equalisation effect. If, with certain load curves or operating positions, it is necessary for reasons of stability, for the inherent weights of the wheel sets to be incorporated into the central ballast, then a further extension movement of the pistons 6 is effected so that the play sl also completely disappears (see Figure 4). Therefore the limiting means 5 bears fixedly against the chassis frame 1, and extension and retraction spring movements are blocked: as indicated above the limiting means 5 need not be separate and may be provided by the limit of extension of the piston 6 from the pressure fluid cylinder 4. To release the arrangement from that position, the pressure fluid cylinders 4 are subjected to pressure on the extension side and thus the arrangement returns to the condition shown in Figure 2, wherein the spring-loaded balls 8 secure the piston 6 in the groove 7.

A possible use is specifically in relation to railway cranes which are designed for transportation in the rail system, a mobile load transport condition and a spring-blocked operating condition. The construction according to the invention improves static stability and travelling stability of the railway crane, while in addition there is the further advantage of a low rate of wear as in the unlocked condition the spring blocking means is not subjected to load forces.

Claims

1. A locking device for wheel axles of mobile cranes for reducing or eliminating spring movement when the crane is converted from a transportation condition to an operating condition, comprising pressure fluid cylinders which are arranged over respective wheel mountings and which are hydraulically interconnected in the longitudinal direction of a chassis frame, wherein, in the transporation condition, the pistons of the pressure fluid cylinders are arranged at a spacing s2 relative to a respective axle bearing, limiting means determining the maximum downward movement of the axle bearing relative to the chassis frame is arranged with a spacing sl, and sl Z-, s2, and wherein there are two operating conditions, one in which sl > 0 and s2 = 0 such that relative movement of hydraulically interconnected axle bearings is possible and one in which sl = 0 and S2 = 0 such that the axle bearings are fully locked.

2. A locking device according to claim 1 wherein each pressure fluid cylinder has in its upper portion one or more guides which each accommodate a respective spring and ball and wherein the piston has a groove for receiving the ball so as to provide a detent for retaining the piston in its transportation position in the absence of fluid pressure.

3. A locking device for wheel axles of mobile cranes for reducing or eliminating spring movement when the crane is converted from a transportation condition to an operating condition, substantially as described with reference to the drawings.

4. A mobile crane having a locking device according to any preceding claim.

5. A mobile railway crane having a locking device according to any one of claims 1-3.

ytr. -c=. TP a -Mce Pub'he:! 1958 at nne Patent Off, ce Rate House 66 71 HIG' London WC1R 4TP he: ccpes mkv be obtaLIed: - Is P ten. Ck-