Method For Connecting And Disconnecting A Crane With A Truck

Abstract

A method for coupling and uncoupling a hydraulically operated lifting crane to and from a truck by connecting the crane boom to a fixed point and moving the crane horizontally and/or vertically in a direction toward or away from the truck, thereby causing cooperating coupling means carried on the crane and the truck, respectively, to engage or disengage.

Description

This invention relates to a rapid coupling device for a lifting crane in connection with a truck and a method for coupling and uncoupling the crane.

One of the drawbacks from which trucks having rigidly or fixedly mounted lifting crane suffers consists in the fact that the weight of the crane reduces the useful load capacity of the truck. Such cranes, which are operated hydraulically, often have a weight of 900-1200 kg. Another drawback is that rigidly mounted cranes on trucks have a rather limited field of application, and the fact that they must always accompany the truck results in a poor utilization of the crane, which during long periods, say during driving, must be out of use.

Because of the rigid fastening of the crane on the truck, both the crane and truck mutually limit their field of application and reduce their utilization.

In its uncoupled position the crane may be used as a stationary crane. Such cranes are, however, heavy and unmanageable, and considerable difficulties arise in connection with the necessary movements of the crane with respect to the truck during the coupling and uncoupling operations.

An object of the present invention is to remedy these drawbacks and thus provide a simple, dependable and effective rapid coupling device for a lifting crane used in connection with a truck, said coupling device securing a rapid and convenient coupling and uncoupling of the crane relative to the truck, and also securing a stable and steady mounting of the crane in its truck position, in which the crane is in a position to withstand the same loads and stresses as an ordinary rigidly mounted truck crane of corresponding size and construction.

A further object of the present invention is to solve the problems which arise during coupling and uncoupling of the crane to the truck in a simple and very advantageous manner, among others from an economical point of view.

According to one aspect of the present invention there is provided a coupling device for a lifting crane having hydraulically operating means, in order to permit rapid coupling and uncoupling of the crane with respect to a truck, in which the lifting crane has coupling means adapted to cooperate with corresponding coupling means carried on the truck, the movements of the crane horizontally and/or vertically being carried out by means of the crane's own operating device during the coupling and uncoupling operations.

According to another aspect of the present invention there is provided a method for coupling and uncoupling a lifting crane having a hydraulically operated, articulated telescopically extendable and contractable boom assembly, and a hydraulically operated, vertically adjustable support device, adapted to cooperate with a base, i.e. the ground, and equipped with a coupling device according to the preceding paragraph, comprising the steps of connecting the crane boom directly to the truck, and thereafter, by means of the crane's own hydraulic operating device through pivoting of the boom sections relative to each other and eventually telescopically contracting or extending of the boom assembly and eventually operating said support device moving the crane horizontally and/or vertically in a direction towards or away from the truck, thereby causing the cooperating coupling means carried on the crane and the truck, respectively, to engage or disengage each other.

The invention will further be described by way of example, with reference to the accompanying drawings wherein FIG. 1 shows the lifting crane both in its coupled and uncoupled positions, as seen from the rear side of the driver's cabin, and FIG. 2 shows means for supporting the crane structure when off the truck. The position occupied by the boom when in the first step of the coupling operation or alternatively the last step of the uncoupling operation, is shown in dotted lines.

In FIG. 1 of the drawing the reference numeral 1 indicates the vertical tubular base of the crane construction. Within said base is mounted a partly extending rotatable column which is rotatable about a vertical axis. At the upper end of said rotatable column the inner end of the main boom 2 is mounted. At the outer end of the main boom 2 a tilt boom is mounted by means of a horizontal pivot pin. A hydraulic piston-cylinder-assembly 6 effects pivoting, of the tilt boom relative to the main boom 2. The tilt boom comprises three telescopically arranged boom sections 3, 4 and 5, of which the innermost 3 and the outermost 5 carry fasteners for the mounting of lift or load hooks (not shown). The lifting crane construction is provided with a hydraulically operated support 7, 8 of known design. These hydraulic supports which constitute stabilizers are movable between an effective position, as shown, and an ineffective position not shown, in the latter position of which the support is located adjacent the longitudinal side of the truck, with the shoe member pointing upwards. When the crane is in use on the truck and when coupling or uncoupling of the crane relative to the truck is to take place, the hydraulic support 7 is caused to occupy its effective position, as shown, with its shoe member in supporting engagement with the ground, in order to relieve the crane and the truck with respect to vertically directed loads acting on the crane.

The lifting crane carries coupling means 10, 11, 18 adapted to cooperate with corresponding coupling means 12, 13, 15 carried on the truck. In the embodiment shown the crane coupling means comprises two aligned bifurcated members 10, only one is visible in the drawing as the other, which is positioned just behind the one shown, is covered by this one. These bifurcated members 10 are adapted for engagement with the coupling means in the form of horizontal bolt members 12 mounted between brackets forming parts of a rigid frame structure 9 carried on the truck. Three such bolt members 12 are arranged in alignment with each other. The two outermost bolt members 12 are adapted to cooperate with the bifurcated members 10, while the intermediate bolt member 12 carries a vertically pivotable stretching member in the form of a tension rod 15, the free end of which is intended to be connected detachably with a lug 18 on the crane assembly. Above the bifurcated members 10 the base of the crane carries an additional lug 11 intended to be detachably connected with one end of a vertically pivotable bracing member 13 in the form of a sloping stay or rod. The engagement of the bifurcated and bolt members 10 and 12 is preferably loose, while the engagement of the lugs 11, 18 and the outer ends of the members 13 and 15, respectively, is secured by means of insertable locking bolts, for example by 1 inch pins. The bracing member 13 may be adjustable with respect to its longitudinal dimension in order to facilitate the connection of its outer end with the lug 11 and in order to adjust the vertical position of the crane base 1 and rotatable column. As the rod 15 is exposed to tension only, the holes for the bolt 12 and for the locking bolt, by means of which it is connected to the lug 18 may be rather wide as compared with the bolt dimensions, whereby the connection of the rod 15 and lug 18 is facilitated. As the connection point of the tension rod 15 is located on the axis of the bolts 12 cooperating with the bifurcated members 10, small pivotal movements of the crane about the bolts 12 do not expose the tension rod 15 to additional stresses.

At the opposite side of the connection place of the lifting crane the truck carries a further coupling member in the shape of a vertically pivotable, bolt-shaped member 17, intended to be inserted into the hollow outer end of the boom assembly and to be connected thereto by means of a transversal bolt.

The support means shown in FIG. 2 is in the form of a base 19 of parallelepiped shape of concrete or other suitable material and equipped with identical coupling means to those on the truck. These coupling means are indicated by the same reference numerals as FIG. 1 but with the addition of a prime (') mark.

When the lifting crane is to be disconnected from the truck, the hydraulically operated support 7, 8 is caused to occupy its effective position as shown with its slide shoe at its lower end in supporting contact with the ground. Thereafter the outermost end of the boom assembly is connected to said vertically pivotable member 17, after which the connection between the crane coupling lugs 11, 18 and the truck bracing members 13, 15 is released by pulling out the locking bolts. The crane is then in a position to automatically i.e. by means of its own hydraulically operated device, comprising the booms parts 2 to 5 and the hydraulically operated support device 7, 8, push itself off the truck and away from the truck by pivoting and telescopically extending the boom sections 2, 3 and 4, 5, respectively. The uncoupling movement of the crane takes place in a vertical plane extending at right angles to the longitudinal axis, i.e. the vertical central plane of the truck. In other words: The coupling and uncoupling movements of the crane takes place through a transversal movement with respect to the truck. This transverse plane in which the lifting crane moves during the coupling and uncoupling operations has a very limited depth which is defined by the outer points of the crane assembly perpendicular to said transverse plane, and the dimension of the crane assembly parallel to the vertical central plane of the truck in the longitudinal direction. The method of coupling and uncoupling as well as the particular rapid coupling device according to the invention is therefore especially advantageous in connection with lifting cranes of the kind being mounted within the very narrow space situated behind the truck driver's cabin, between the latter and the loading area of the truck. Such lifting cranes are far superior to those which are mounted rearwardly on the loading area, as the latter type of cranes do not permit the loading area to be used for tilting the useful load by pivotal movements of the loading area in a vertical plane thus positioning the loading area in a sloping position. Another advantage of lifting cranes of the kind shown on the drawing is that they do not interfere with the useful load during loading and unloading. The narrower the space available for the mounting or coupling of the crane on the truck is, i.e. in this case the distance in the longitudinal direction of the truck, the more accurate the coupling and uncoupling movements have to be, and the present coupling and uncoupling method and rapid coupling device attend to these accuracy and precision requirements in a simple, rapid and effective manner.

When the crane, by its own hydraulic power, is pushed outwards from the truck and occupies the position shown to the left in the drawing, the crane is supported in a vertical position by means of supports, not shown, e.g. in the form of stays, bars, etc., arranged in a sloping position with their upper ends connected to the crane construction, to the bifurcated members 10. Thereafter the connection between the outer, hollow end of the boom and the pivotable member 17 is released and the boom assembly is caused to occupy a suitable position, with its outer end supported on the ground. If the hydraulic drive means, for example, a pump, is carried on the truck the hydraulic tubes to the control valve of the crane are disconnected. From the hydraulic control valve further tubes extend to the different piston-cylinder-assemblies such as 6, or the hydraulically operated support 8. The crane then occupies a stationary position, and may later be connected to the same or another truck. It is, however, intended to use the crane in its uncoupled position as a stationary crane and proper hydraulic drive means, such as a pump etc., must then be available at the place of uncoupling, whereby the field of application is widened and full utilization of the crane is possible. The fact that the crane can be uncoupled from one truck and coupled to another also widens the field of application for the combination crane and truck allowing increased utilization of both of them.

During the coupling of the lifting crane the same steps are carried out, but in the reverse sequence. The truck is then moved to occupy a suitable position with respect to the crane as indicated in the drawing, after which the pressure fluid tubes are connected to the hydraulic control valve of the crane. The boom assembly is then caused to occupy the position shown in dotted lines, and by pivoting and telescopically contracting the boom assembly the crane pulls itself while sliding on the support shoe towards the truck, this movement takes place in a vertical plane extending transverse to the longitudinal vertical central plane of the truck. The adjustment of the crane bifurcated members 10 in the vertical direction with respect to the bolt members 12 on the truck is carried out by operating the support device 7 by means of its hydraulic cylinder, in order to lower or raise the bifurcated members 10 relative to the bolt members 12 to allow for a proper engagement. During driving and during very easy lifting operations the support 7 is placed in its ineffective position adjacent the side of the truck with its slide shoe pointing upwards.

Claims

We claim:

1. A method for connecting a hydraulically operated lifting crane to a truck having a driver's cabin and a loading area in the relatively narrow space between the driver's cabin and the loading area, the lifting crane comprising a rotatably mounted column having a vertical axis of rotation and carrying at its upper end a boom assembly pivotable in a vertical plane, a stabilizer support device adapted to cooperate with a base, and the lifting crane, provided with coupling means adapted to cooperate releasably with corresponding coupling means on the truck and located in uncoupled position a distance from the truck, resting on said support device, at first is temporarily connected with the outer end of its boom assembly to a fixed point, whereafter the entire crane construction by means of the crane's own hydraulic power means by pivoting of the boom assembly in a vertical plane, is moved in a direction towards the truck, sliding along said base while resting on said support device, whereafter the coupling means on the crane are brought into engagement with those on the truck after a height position adjustment of the former relatively to the latter has taken place.

2. A method for disconnecting a hydraulically operated lifting crane from a truck according to claim 1, wherein the lifting crane, resting on said support device, is temporarily connected with the outer end of its boom assembly to a fixed point, whereafter said cooperating coupling means on the crane and the truck, respectively, are disengaged by means of its own hydraulic power means and moved away from the truck.

3. A method for disconnecting a hydraulically operated lifting crane from a truck according to claim 1, wherein the boom assembly has one or more telescopically extendable and retractable boom sections, said crane construction being moved towards the truck by telescopic displacement thereof.