GB2094753A - Mobile telescopic crane - Google Patents

Abstract

A telescopic jib 9 is removably supported upon a support jib 4 of a vehicle 1. During movement from site to site, the telescopic jib is carried on a transport vehicle from which it is drawn onto the support jib using a lifting mechanism 7 with which the support jib is provided. The support jib 4, at least at its forward end, is of open-topped channel section and has rollers to guide the telescopic jib 9 during transfer. The two jibs 4, g are fastened together in use so as to prevent both longitudinal and transverse movement of the telescopic jib 9 relative to the support jib 4. <IMAGE>

Description

SPECIFICATION Improved mobile telescopic crane An advantage of a mobile telescopic crane is that it may be brought into use within a short time of reaching the work site, without having to be erected and fitted out as is necessary in the case of a lattice mast crane. On the other hand, because a mobile telescopic crane is more expensive than a mast crane, it is generally used only for tasks for which a mast crane is not suitable: for example, work which must be carried out without delay, including the erection of larger cranes or the removal of wrecked vehicles.

Another disadvantage of a mobile telescopic crane is that, if it is constructed to lift loads measured in hundreds of tonnes, the size of the jib results in the overall vehicle being of such length and height that it is too large to travel on public roads. It has therefore been proposed to provide a mobile telescopic crane unit including two vehicles. One of the vehicles (the crane vehicle) is used to support and operate the telescopic jib when the crane is in use. The other vehicle (the transport vehicle) is used to transport the telescopic jib during movement from site to site. With the telescopic jib carried on the transport vehicle, both vehicles are of a suitable size to travel on the public roads. When the vehicles reach the work site, the telescopic jib is removed from the transport vehicle and mounted on the crane vehicle.After use, the jib is demounted from the crane vehicle and transferred back to the transport vehicle. An example of such a crane unit is known from United States patent specification No. 3954 1 93. In preparation for transporting the crane, the telescopic jib is demounted by using its luffing rams to lower it onto the transport vehicle, the rear end of which is brought up to the rear end of the crane vehicle. The transport vehicle is equipped with two trolleys. When the telescopic jib is to be taken on board, a rearward one of the trolleys is positioned at the end of the transport vehicle nearer the crane vehicle, while the other trolley is located approximately mid-way along the transport vehicle.

The rearward trolley, i.e. that nearer the end of the transport vehicle, has a seating that can be raised and lowered and which serves for lifting the luffing rams at the foot end of the telescopic jib out of their bearings on the crane vehicle following removal of the bearing pins. Thereafter, the two trolleys with the telescopic jib placed on them are pushed forwardly until the rearward trolley reaches the approximate centre of the transport vehicle. This trolley is now lowered so that the telescopic jib rests with its foot end upon a platform of the transport vehicle. Mounting of the telescopic jib on the crane vehicle is carried out in the reverse sequence. These operations which must be carried out in order to mount and demount the telescopic jib are complicated, and the devices required for carrying them out are expensive.

In order to overcome the disadvantages associated with the known crane, it is proposed herein that the crane vehicle should have a support jib which serves as a seating for the telescopic jib, ram means for adjusting the support jib, and interengagable parts for transmitting shear forces which act perpendicularly to the telescopic jib. A number of advantages are obtained with this construction. First, the luffing rams and the bearings which support them on the crane vehicle do not have to be removed from the crane vehicle during demounting of the telescopic jib.

The support jib, to which these rams remain connected at all times, serves as a rest for the telescopic jib. By giving the support jib a suitable construction, the telescopic jib may be mounted in place in a very simple fashion by depositing the telescopic jib onto the support jib and sliding it into a position in which the parts at the foot ends of the jibs may be interengaged. These parts may transmit the perpendicular shear forces by way of a form fitting (formschlussig) connection. The telescopic jib is substantially longer than the support jib and therefore projects beyond the forward end of the latter. The prevailing tendency is for the telescopic jib to topple over the forward end of the support jib. The requirement is thus for an arrangement which will counteract this tendency.Consequently, the foot ends of the two jibs may include a stop on the support jib and a projection on the telescopic jib for engagement beneath the stop when the telescopic jib is mounted in place. Since mounting and demounting of the telescopic jib are carried out by moving it in the direction longitudinally of the support jib, the stop and projection readily interengage and conveniently have complementary wedge forms. Removable fixing means may be provided to prevent relative longitudinal movement between the two jibs. As an alternative to the interengagement of parts provided on the jib, means separate from the jib may be applied to them to hold the foot ends together in the sense of preventing the telescopic jib toppling over the forward end of the support jib.

To facilitate its support as well as movement of the telescopic jib relative to the support jib, the latter may have at least in part the form of an open-topped channel in which the telescopic jib is received. Guide rollers or other devices may easily be fitted in the channel for engagement at least with the underside and possibly the lateral sides of the telescopic jib during its movement towards and away from the mounted position. To prevent the telescopic jib toppling backwards when raised to a steep angle as a reaction to a sharply reduced load, disengagable interlocking means may be provided at the forward end of the support jib.

Mounting of the telescopic jib may be carried out very simply by providing the support jib with a lifting mechanism adapted to draw the telescopic jib from the transport vehicle onto the crane vehicle, this mechanism preferably being located rearwardly of the position of the foot end of the support jib and including a power operated drum onto which a cable may be drawn. By fitting a cable sheave at the forward end of the support jib, the same mechanism may be used during demounting of the telescopic jib by running the cable from the drum around the sheave and connecting it to the telescopic jib at or near its foot end. It will be noted that the support jib is raisable and lowerable by the rams whether or not the telescopic jib is mounted thereon.

Since the support jib is equipped with its own lifting mechanism normally used for mounting and demounting the telescopic jib, the support jib is thus suited for use as an auxiliary crane for small lifting operations.

In the drawings: Figure í shows in diagrammatic side view the crane vehicle from which the telescopic jib has been removed, Figure 2 is a view similar to Fig. 1 but with the telescopic jib mounted thereon, Figure 3 shows to an enlarged scale and inside the plan views the detail A in Fig. 2, and Figure 4 is a cross-section to an enlarged scale taken in the region at B in Fig. 2.

Referring to the drawings, a mobile telescopic crane unit includes a transport vehicle (not shown) on which a telescopic jib is carried during movement along the roads between one site and another, and a crane vehicle 1 on which the jib is mounted for use on site. The crane vehicle is shown in Fig. 1 as it appears during transport, i.e. without the telescopic jib. The crane vehicle includes a wheeled lower chassis of the type conventional in such heavy vehicles, and an upper chassis 2 supported on the lower chassis for rotation about a vertical axis 3. Mounted on the upper chassis is a short support jib 4 which remains permanently in place and is raisable and lowerable about a foot bearing, not shown, by means of luffing rams 5 which also remain permanently connected between the upper chassis and the support jib.Referring briefly to Fig. 4, the support jib at least at its forward end is of open-topped channel section and has bearing segments 1 3 to support the telescopic jib when it has been mounted in place. The support jib is also equipped with rollers (not shown) to support and guide the telescopic jib as it is transferred from the transport vehicle onto the crane vehicle, and vice versa. Such displacement of the telescopic jib is carried out by a secondary lifting mechanism 7 provided on the support jib and including a power operated cable drum. The foot end of the telescopic jib has suitable connecting points for the cable which may be taken around a cable sheave 8 at the forward end of the support jib during demounting of the telescopic jib.

When the telescopic jib occupies its mounted position shown in Fig. 2, the foot end of the telescopic jib is located in the region of the foot end of the support jib. As the telescopic jib is drawn into this position, parts of the foot ends of the two jibs interengage as shown in Fig. 3 to transmit forces in the vertical plane, thereby counteracting the tendency of the telescopic jib to topple over the forward end of the support jib. The parts in question include a wedge-like projection 6 on the foot end of the support jib received within a complementary cavity in the foot end of the telescopic jib. Essentially, having regard to the function to be performed, these parts may be reduced to a stop 6 on the foot end of the support jib with a tapering surface for cooperation with a complementary surface on a projection 9'.With the telescopic jib so mounted in position, the foot ends of the two jibs are coupled by means of bolts 10 passed through the side walls of the jibs, or by other means. Longitudinal movement of the telescopic jib relative to the support jib is restrained by means of lugs 11 on the support jib which is coupled by bolts 1 2 to lugs on the support jib. Alternatively, suitable bolted connections may be employed to prevent relative longitudinal movement of the jibs and transmit the shear forces without using interengaging stops and projections.

Referring again to Fig. 4, it will be seen that the outer casing of the telescopic jib is in the form of a box-section which rests on the bearings 1 3 within the channel-form support jib. The extensible jib parts telescope within this section under the action of a piston and cylinder unit in the conventional way. In order to prevent the telescopic jib from falling backwards when the jibs have been raised and the load is released suddenly, pins 14 are passed removably through the side walls of the support jib and the side wall of the outer casing of the telescopic jib in the vicinity of the forward end of the support jib.

The transport vehcile is so constructed that the foot end of the telescopic jib projects sufficiently from its rear end that, when the transport and crane vehicles are brought into a transfer position, the foot end of the telescopic jib is situated above the cable sheave 8. If the overhang of the telescopic jib is not large enough to enable the jib to be transferred with the crane vehicle in the position shown in Fig. 1, the crane vehicle may be arranged transversely of the transport vehicle and the upper chassis rotated so that the support jib projects at rightangles from the length of the vehicle. The transport vehicle is equipped with devices which permit the telescopic jib to be aligned with the support jib before transfer onto the support jib and with rollers for other guides to facilitate movement of the telescopic jib relative to the transport jib.The cable of the lifting mechanism 7 is attached to the foot end of the telescopic jib and the cable drum rotated to draw the telescopic jib from the transport vehicle onto the support jib. Because the lifting mechanism is located rearwardly of the stop 6 which limits the movement of the telescopic jib, the latter may be brought fully into its mounted position by the lifting mechanism. With the telescopic jib in position, the fixings 10, 1 2 and 14 are applied. To demount the telescopic jib, these fixings are removed, the cable passed around the sheave at the forward end of the support jib, and the lifting mechanism 7 operated to displace the telescopic jib in the opposited direction.

The main lifting mechanism 1 5 is permanently connected to the telescopic jib 9. After mounting of the telescopic jib 9, the main lifting mechanism and also the extending cylinder of the telescopic jib 9 are connected with the hydraulic system of the upper chassis.

Claims (14)

1. A crane unit including a transport vehicle for supporting a telescopic jib during transportation and a crane vehicle on which the telescopic jib is mounted during use, the crane vehicle including a lower chassis and an upper chassis movable about a vertical axis relative to the lower chassis, a support jib carried by the upper chassis and serving as a seating for the transferable telescopic crane jib, ram means for adjusting the support jib, the two jibs being provided with interengagable parts for transmitting shear forces which act perpendicularly to the telescopic jib when the latter is mounted upon the support jib.

2. A crane as claimed in claim 1, wherein the parts for transmitting shear forces are engagable and disengagable upon movement of the telescopic jib longitudinally of the support jib.

3. A crane according to claim 1 or claim 2, wherein the foot end of the telescopic jib has a projection engagable beneath a stop on the support jib.

4. A crane according to claim 3, wherein the stop has the shape of a wedge tapering away from the foot end of the support jib and the projection has a complementary shape tapering towards the foot end of the support jib.

5. A crane according to any preceding claim, wherein the telescopic jib has a releasable securing device in the region of its foot end, which device serves to prevent relative longitudinal movement of the jibs when the telescopic jib is mounted upon the support jib.

6. A crane according to any preceding claim, wherein a releasable locking device is disposed at the forward end of the support jib for connecting the jibs when the telescopic jib is mounted upon the support jib.

7. A crane according to any preceding claim, wherein the forward end of the support jib has an upwardly open seating complementary to the external form the telescopic jib and receiving the same.

8. A crane according to any preceding claim, wherein at least part of the support jib is in the form of an open-topped channel.

9. A crane according to any preceding claim, wherein the support jib is provided with guide rollers for the telescopic jib, said rollers cooperating at least with the underside of the telescopic jib.

10. A crane according to any preceding claim, wherein the support jib is provided with a lifting mechanism and a cable sheave at its forward end.

11. A crane according to claim 10, wherein the cable sheave is so disposed that the highest point of its circumference lies below the support plane for the telescopic jib during mounting.

1 2. A crane vehicle as defined in any preceding claim.

1 3. A method of assembling a mobile telescopic crane, comprising bringing into adjacent positions a transport vehicle and a crane vehicle such that a telescopic jib borne by the transport vehicle overhangs a support jib on the crane vehicle, and drawing the telescopic jib from the transport vehicle onto the support jib, and interlocking at least the foot ends of the telescopic and support jibs.

14. A crane vehicle having a support jib in the form of an open-topped channel, a removable telescopic jib supportable within said channel, the channel being equipped with means for guiding the telescopic jib therealong into a position in which the foot end of the telescopic jib is juxtaposed to the foot end of the support jib, and means for securing the foot ends of the jibs together in the sense of preventing relative longitudinal and perpendicular movements thereof.

1 5. A crane substantially as hereinbefore described with reference to and as illustrated in the drawings.