GB2149750A - Improvements in mobile cranes - Google Patents

Abstract

A mobile crane comprises an undercarriage 3 on which is supported an upper carriage. The upper carriage consists of separable front and rear parts 1 and 4. The front part bears the main jib and the rear part bears the counterweights 5 and stays. The carriage parts are connectable directly or by way of an interposable carriage spacer member 7. The detachable rear part is optionally supportable on an additional undercarriage 6. <IMAGE>

Description

SPECIFICATION Improvement in mobile cranes It is known for a mobile crane to have an undercarriage on which is supported an upper carriage bearing the main jib, counter-weights and stays for the jib. Although the undercarriage may be supported on wheels, endless tracks are used, for the undercarriage particularly if the crane has a high carrying power. However, the moments applied to the crane by the load can only be increased by changing the counter-weights. The load carrying ability of a mobile crane is therefore limited. On the other hand, a crane capable of accepting a heavy load occupies a very large space, and is inconvenient when used for lighter loads.

The present proposal is for a mobile crane design which can be used with lighter loads and, moreover, for heavier loads, with few modifications. To this end, the upper carriage is divided into front and rear parts which can be connected to each other directly so that the counterweights provide a small moment to counterbalance that of the load, or by way of a spacer so that the counterweights provide a larger counterbalance moment.

In this way, the distance between the front part bearing the jib and the rear part receiving the counterweights can be increased so that a larger machine which can take up higher moments is available for special loads whereas the mobile crane does not occupy an unacceptable amount of space in normal cases.

The drawing shows the proposed crane in the operating mode with the interposed spacer.

The proposed crane comprises a tracked undercarriage 3 on which is supported for rotation the front part of an upper carriage 1 bearing the main jib 2. The rear part 4 of the upper carriage is separable from the front part and supports the counteweights 5. The rear part may be cantilevered or placed on an additional mobile undercarriage 6, shown as a second tracked vehicle. The connection between the front part and rear part are made by a welded frame construction 7, as shown, provided with winches for optional use. The frame 7 is, when required, bolted or otherwise secured to the separable parts of the upper carriage. When not required, it may be transported on the vehicle 6.

It can easily be seen that this extension of the upper carriage enables the crane to take up substantially greater load moments, in which case, however, the entire machine requires more space.

For lighter loads, the front portion and rear portions are directly connected to each other, and the mobile crane requires only a small space and the counterweights are supported in cantilevered fashion. The vehicle 6 is not then required.

1. A mobile crane comprising an undercarriage on which is supported an upper carriage separable into front and rear parts, the front part bearing the main jib and the rear part bearing the counterweights, the carriage parts being connectable directly or by way of an interposable carriage spacer member, the detachable rear part being optionally supportable on an additional undercarriage.

2. A mobile crane according to claim 1, wherein the upper carriage spacer member consists of a welded frame structure provided with winches for optional use.

3. A mobile crane substantially as hereinbefore described with reference to the drawing.

4. For use in assembling a crane: an undercarriage supporting a forward upper carriage part bearing a jib; a rearward upper carriage part bearing a counterweight, and a spacer; the rearward upper carriage part being connectable with the forward part directly or though the intermediary of the spacer.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvement in mobile cranes It is known for a mobile crane to have an undercarriage on which is supported an upper carriage bearing the main jib, counter-weights and stays for the jib. Although the undercarriage may be supported on wheels, endless tracks are used, for the undercarriage particularly if the crane has a high carrying power. However, the moments applied to the crane by the load can only be increased by changing the counter-weights. The load carrying ability of a mobile crane is therefore limited. On the other hand, a crane capable of accepting a heavy load occupies a very large space, and is inconvenient when used for lighter loads. The present proposal is for a mobile crane design which can be used with lighter loads and, moreover, for heavier loads, with few modifications. To this end, the upper carriage is divided into front and rear parts which can be connected to each other directly so that the counterweights provide a small moment to counterbalance that of the load, or by way of a spacer so that the counterweights provide a larger counterbalance moment. In this way, the distance between the front part bearing the jib and the rear part receiving the counterweights can be increased so that a larger machine which can take up higher moments is available for special loads whereas the mobile crane does not occupy an unacceptable amount of space in normal cases. The drawing shows the proposed crane in the operating mode with the interposed spacer. The proposed crane comprises a tracked undercarriage 3 on which is supported for rotation the front part of an upper carriage 1 bearing the main jib 2. The rear part 4 of the upper carriage is separable from the front part and supports the counteweights 5. The rear part may be cantilevered or placed on an additional mobile undercarriage 6, shown as a second tracked vehicle. The connection between the front part and rear part are made by a welded frame construction 7, as shown, provided with winches for optional use. The frame 7 is, when required, bolted or otherwise secured to the separable parts of the upper carriage. When not required, it may be transported on the vehicle 6. It can easily be seen that this extension of the upper carriage enables the crane to take up substantially greater load moments, in which case, however, the entire machine requires more space. For lighter loads, the front portion and rear portions are directly connected to each other, and the mobile crane requires only a small space and the counterweights are supported in cantilevered fashion. The vehicle 6 is not then required. CLAIMS

1. A mobile crane comprising an undercarriage on which is supported an upper carriage separable into front and rear parts, the front part bearing the main jib and the rear part bearing the counterweights, the carriage parts being connectable directly or by way of an interposable carriage spacer member, the detachable rear part being optionally supportable on an additional undercarriage.

2. A mobile crane according to claim 1, wherein the upper carriage spacer member consists of a welded frame structure provided with winches for optional use.

3. A mobile crane substantially as hereinbefore described with reference to the drawing.

4. For use in assembling a crane: an undercarriage supporting a forward upper carriage part bearing a jib; a rearward upper carriage part bearing a counterweight, and a spacer; the rearward upper carriage part being connectable with the forward part directly or though the intermediary of the spacer.