GB2291033A - Transfer bridge for dock leveler - Google Patents

Abstract

A transfer bridge having a bridge plate (1) which is pivotably mounted on an edge of a dock (3) and is provided with a retractable and extendible, or respectively, an inwardly and outwardly pivotable extension member (7), which is situated at the normally front end of said bridge plate (1), for support on a platform (8) to be loaded and/or unloaded. The bridge plate (1) is upwardly pivotable by means of at least one hydraulic lifting cylinder (11), the pressure medium (14) of which escapes from the lifting cylinder (11) via a return line (15) during the lowering of the bridge plate. The bridge plate (1) is provided with a sensor indicator (21), which responds when the front end (7) of the bridge plate (1), or respectively its extension member (5), touches or significantly touches the platform (8), and said sensor is configured such that it is operable to close the return line (11') of the lifting cylinder or cylinders (11). Preferably the sensor (21) can be switched off when desired. <IMAGE>

Description

TRANSFER BRIDGE FOR PLATFORNS The invention relates to a transfer bridge for platforms having a pivotably mounted bridge plate which is upwardly pivotable by means of at least one hydraulic lifting cylinder, the pressure medium of which escapes from the lifting cylinder via a return line during the lowering of the bridge plate.

With known bridges of this type, the bridge plate is supported at its front end on the platform to be loaded or unloaded and assumes a so-called floating position during the operation of the bridge so as to permit the bridge plate to follow the change in height of the vehicle floor or platform, such a change being set with variable loading states of the loading platform or respectively of the platform of the associated vehicle.

This mode of operation, however, which is desirable per se, can only be achieved with those vehicles which have a suitable carrying capacity. This is not always the case, such as with so-called lightweight heavy goods vehicles, for example.

On this basis, the invention seeks to provide the initially mentioned bridge so that a bridging operation can occur even when the platform of the heavy goods vehicle or the like cannot bear the supporting forces of the transfer bridge and the weight of the load and of the load conveyor.

To achieve this object, according to the invention, the bridge is provided with an indicator, which responds when the front end of the bridge plate, or respectively its extension, touches the platform of the heavy goods vehicle or the like, and said indicator is also so configured that it can shut-off the return line of the lifting cylinder.

Accordingly, the return line of the lifting cylinder can be shut-off by the indicator and, in consequence, the resilience of the lifting cylinder can be eliminated when the front end of the bridge plate rests on the heavy goods vehicle. The lifting cylinder carries a corresponding load under these conditions. It is self-evident that this leads to a corresponding removal of load from the vehicle platform. If the vehicle platform is now loaded with the bridge plate fixed and the vehicle platform drops, e.g. as a result of the load on the vehicle suspension, the bridge plate follows accordingly until it comes into contact again with the vehicle platform in order to permit the lifting cylinder to resume a load or respectively to permit its return line to be shut-off again.

It is advantageous to have a switching means associated with the indicator, which can be switched-on or -off by said switching means, so that the bridge can be set to a certain extent to small and large vehicles.

It is also advantageous when the effective width of the bridge plate, or respectively its extension, is adjustable, e.g. by means of laterally mounted push-in projection members or flaps. In consequence, the bridge can be set to the mainly smaller width of the smaller vehicles.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a longitudinal sectional view through a transfer bridge mounted on a platform and in its operational position; Fig. 2 is a longitudinal sectional view through the bridging device of Fig. 2 prior to the operational position being reached; and Fig. 3 is a detail of Fig. 1.

A bridge plate 1 of a transfer or transshipment bridge is mounted on an edge of the platform 3 pivotal about a horizontal axle 2 and said platform has a recess 4 for receiving the bridge, the bridge plate 1 being insertable in said recess. Situated at the front end of the bridge plate 1 there is a retractable and extendible extension member 5 having a sliding member 6, which is displaceable longitudinally relative to the bridging device. A supporting member 7 is secured at its front end to the slide member 6, and is to be supported on a platform 8 of a vehicle (not shown), which is to be loaded and/or unloaded.In order to be able to adapt the supporting member 7 to the width of the platform 8, said supporting member is advantageously provided on both sides with edge flaps 9 which can pivot into the plane of the bridge or downwardly (as shown in the drawing) by means of pivotal cylinder 10.

In order to permit the bridge plate 1 to be pivoted upwardly, it is provided at both lateral edges with lifting cylinders 11, which are supported at their lower end on the platform base. These single-acting lifting cylinders 11 are supplied by a hydraulic pump 12 having non-return valve 13 from an oil container 14. In consequence, the bridge plate 1 can be pivoted upwardly.

An electrically operable return valve 15 is also provided. It is actuated when the bridge plate 1 is to be lowered. The oil escapes into the oil container 14 under the action of the weight of the bridge plate 1. An excess-pressure valve 16 is additionally provided for safety reasons.

If, in consequence, the return valve 15 is shutoff, the bridge plate 1 cannot be lowered; the weight is now borne by the lifting cylinder or cylinders 11.

If the extension member 5 is in the position shown in Fig. 2, it is supported at its rear end at a on the underside of the cover sheet 1' of the bridge plate 1 and at its front end on laterally mounted rollers 20, which are secured to the bridge plate 1. A gap s is thereby produced in the region of the front portion of the sliding member 6, and a sensor 21 (indicator) is associated with said gap; said sensor is advantageously mounted on the sliding member 6 and is in active connection with the electrically operated return valve 15 via a line 22, a control 23 and an additional line 24.

If the bridge plate 1 according to Fig. 1 is lowered to such an extent that the supporting member 7 touches the platform 8, the gap s is eliminated. The sensor 21 responds and actuates the return valve 15. In consequence, the lifting cylinder 11 becomes pressureresistant i.e. locked. Cylinder 11 assumes the load and carries the bridge plate 1 and the load situated thereon, said load being transferable now to the platform 8 without any significant influence on the heavy goods vehicle. If the platform 8 drops as a result of an increase in load (charge), a gap s is again formed, which permits the bridge plate 1 to pivot again, since the sensor 21 releases the return flow of the lifting cylinder 11 if there is a gap s. If the bridge plate 1 has followed the platform 8 to a certain extent, the sensor 21 becomes effective again with the already described consequences.

The invention can also be utilised with other bridges, e.g. those which have an inwardly and outwardly pivotable extension member. The switch, by means of which the sensor 21 can be switched-on, is so disposed that it is readily accessible to the operator. This also applies to the actuating elements of the edge flaps 9, by means of which the bridging device can be set to heavy goods vehicles having a greater or smaller width.

Claims (5)

1. A transfer bridge for a platform having a bridge plate (1) which is to be pivotably mounted on an edge of the platform (3) and is provided with a retractable and extendible, or respectively, an inwardly and outwardly pivotable extension member (7), which is situated at the normally front end of said bridge plate (1), for support on a further platform (8) to be loaded and/or unloaded, the bridge plate (1) being upwardly pivotable by means of at least one hydraulic lifting cylinder (11), the pressure medium (14) of which escapes from the lifting cylinder (11) via a return line (15) during the lowering of the bridge plate, wherein the bridge plate (1) is provided with a sensor indicator (21), which responds when the front end (7) of the bridge plate (1), or respectively of its extension member (5), touches or significantly touches the platform (8), and said sensor is configured such that it is operable to close the return line (11') of the lifting cylinder or cylinders (11).

2. A transfer bridge as claimed in claim 1, wherein the effective width of the supporting member (7) of the extension member (5) can be reduced, e.g. by means of edge flaps (9) or push-in projection members.

3. A transfer bridge as claimed in claim 1 or 2, wherein a switching means is associated with the sensor (21) for switching the sensor on and off.

4. A transfer bridge as claimed in claim 1, wherein the sensor or indicator (21) serves to monitor a gap (s), which is produced between the bridge plate (1) and its extension member (5) when the extension member is not supported.

5. A transfer bridge for platforms substantially as herein described with reference to the accompany drawings.