GB2139184A - Jib crane and its method of erection - Google Patents

Abstract

The jib of a mobile jib crane consists of parts 1, 1a, 1b and 1c which are transported from place to place in telescoped relation. On site, the parts are extended and bolted together at 10. The part 1 is connected to a foot piece 5 and guy ropes A are connected to a frame 7 which is pivoted to raise the jib. <IMAGE>

Description

SPECIFICATION Jib crane and jib erection method An advantage of a mobile crane having a guyed jib compared with a crane having a hydraulically operated telescopic jib is that it can be subjected to greater lifting forces. This is because a jib which does not vary in length in use can be of lighter construction and therefore have a greater carrying capacity. Hydraulic telescopic jibs must be of correspondingly heavier construction because of the need to resist flexing and buckling of the hydraulic cylinders, As a result, the jib is heavier and the load which it can carry must be less. On the other hand, the individual parts of a guyed jib, which often are of the lattice-mast type, are transported from site to site individually and must be secured together on site, so that assembly is a time consuming operation.

According to the present proposal, the time needed to assemble a guyed jib of a mobile crane is reduced by making the parts of telescopic construction so that they are transported one inside the other. To assemble the jib, it is merely necessary to withdraw one part from another and secure them together.

The jib may take the form of an intermediate component located between a foot piece, and a head piece, or other jib components. Using appropriate means of connection, the telescoping jib parts may be interposed between other inextensible jib parts for the purpose of lengthening the jib, or the telescoping jib parts may simply be connected to the foot piece of the crane vehicle provided for inextensible jib parts. In the same way, a standard head piece which carries the crane sheave may also be attached.

The guy ropes may be laid on the jib during transportation. Conveniently, the guy ropes remain permanently attached to one end of the jib compo nent so that assembly time is further shortened. The telescopic parts of the jib may be extended and retracted using conventional mechanical or hyd raulic mechanisms, for example, spindles, ropes, chains or piston and cylinder units.

In the drawings: Figure lisa side view of a jib in the course of transportation, Figure 2 is a plan view of the jib shown in Figure 1, Figure 3 is a side elevation showing a first stage of the jib erection operation, and Figure 4 is a side elevation showing the erected jib.

Referring to Figures 1 and 2, a lattice-mast type of jib for a mobile crane is transported from site to site on a vehicle 2 consisting of multi-axle bogies 2a and 2b which are coupled together and provided with a tow-bar. The jib consists of four parts (shown at 1, 1 a 1 b, ic in Figure 3) which telescope one within another during transportation, part 1 being the outermost. Optionally, the inner part 1c may be permanently fitted with a head piece 11 shown in broken lines in Figures 1 and 2. Guy ropes A permanently connected to the head part are laid on the jib during transportation.

Referring now to Figures 3 and 4, the jib is mounted in use on a crane vehicle having lateral supports 4, a foot piece 5 and an A-frame 7. Ropes 8 are provided for raising and lowering the A-frame, and a counterweight 9 is provided to counterbalance the jib.

Assembly takes place by positioning the crane vehicle transversely of the end of the transportation vehicle, extending the lateral supports, and lowering the A-frame into a position in which the guy ropes A may be connected to it. The foot piece 5 which is articulated to the crane vehicle is then bolted at 6 to the foot end of the jib. Subsequently, or simultaneously, the telescopic parts 1 a and 1 bare extended from the outer part 1-in the direction shown by the arrow in Figure 3. Any suitable means may be used for extending the jib parts. When the parts have reached their extended positions, they are bolted together as indicated diagrammatically at 10. Alternatively, the foot end of the jib may be pivotally connected to the crane vehicle instead of connected to a pivotal footpiece.

Operating mechanism on the crane vehicle is now operated to shorten the rope 8 and raise the A frame, thereby tightening the guy ropes. Further pivotal movement of the A frame raises the jib about its point of articulation on the crane vehicle into an operating position as shown in Figure 4. Further adjustment of the length of the ropes 8 raises or lowers the jibs as required.

1. A method of erecting the jib of a mobile crane, comprising transporting the jib into a position adjacent a crane vehicle, the parts of the jib being telescoped one within another during transportation, connecting the foot end of the jib to the crane vehicle, extending the parts of the jib and securing the extended parts together, connecting the guy ropes of the jib to a frame of the vehicle, and adjusting the inclination of the frame to raise the jib into its working position.

2. Ajib for a mobile crane comprising a plurality of telescopable parts capable of being secured one to another in an extended condition.

3. A jib according to claim 2, constituting an intermediate component between a foot piece and a head piece or other non-adjustable jib oarts.

4. Ajib according to claim 2 or claim 3, wherein mechanism for extending and retracting the telescoped parts comprise spindles, ropes, chains or the like.

5. A jib according to claim 2 or claim 3, wherein mechanism for extending and retracting the telescoped parts of the jib is hydraulic, comprising piston and cylinder units or the like.

6. Ajib according to any of claims 2 to 5, wherein the jib is transportable from site to site with guy ropes laid thereon.

7. A method for erecting a jib substantially as hereinbefore described.

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

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Jib crane and jib erection method An advantage of a mobile crane having a guyed jib compared with a crane having a hydraulically operated telescopic jib is that it can be subjected to greater lifting forces. This is because a jib which does not vary in length in use can be of lighter construction and therefore have a greater carrying capacity. Hydraulic telescopic jibs must be of correspondingly heavier construction because of the need to resist flexing and buckling of the hydraulic cylinders, As a result, the jib is heavier and the load which it can carry must be less. On the other hand, the individual parts of a guyed jib, which often are of the lattice-mast type, are transported from site to site individually and must be secured together on site, so that assembly is a time consuming operation. According to the present proposal, the time needed to assemble a guyed jib of a mobile crane is reduced by making the parts of telescopic construction so that they are transported one inside the other. To assemble the jib, it is merely necessary to withdraw one part from another and secure them together. The jib may take the form of an intermediate component located between a foot piece, and a head piece, or other jib components. Using appropriate means of connection, the telescoping jib parts may be interposed between other inextensible jib parts for the purpose of lengthening the jib, or the telescoping jib parts may simply be connected to the foot piece of the crane vehicle provided for inextensible jib parts. In the same way, a standard head piece which carries the crane sheave may also be attached. The guy ropes may be laid on the jib during transportation. Conveniently, the guy ropes remain permanently attached to one end of the jib compo nent so that assembly time is further shortened. The telescopic parts of the jib may be extended and retracted using conventional mechanical or hyd raulic mechanisms, for example, spindles, ropes, chains or piston and cylinder units. In the drawings: Figure lisa side view of a jib in the course of transportation, Figure 2 is a plan view of the jib shown in Figure 1, Figure 3 is a side elevation showing a first stage of the jib erection operation, and Figure 4 is a side elevation showing the erected jib. Referring to Figures 1 and 2, a lattice-mast type of jib for a mobile crane is transported from site to site on a vehicle 2 consisting of multi-axle bogies 2a and 2b which are coupled together and provided with a tow-bar. The jib consists of four parts (shown at 1, 1 a 1 b, ic in Figure 3) which telescope one within another during transportation, part 1 being the outermost. Optionally, the inner part 1c may be permanently fitted with a head piece 11 shown in broken lines in Figures 1 and 2. Guy ropes A permanently connected to the head part are laid on the jib during transportation. Referring now to Figures 3 and 4, the jib is mounted in use on a crane vehicle having lateral supports 4, a foot piece 5 and an A-frame 7. Ropes 8 are provided for raising and lowering the A-frame, and a counterweight 9 is provided to counterbalance the jib. Assembly takes place by positioning the crane vehicle transversely of the end of the transportation vehicle, extending the lateral supports, and lowering the A-frame into a position in which the guy ropes A may be connected to it. The foot piece 5 which is articulated to the crane vehicle is then bolted at 6 to the foot end of the jib. Subsequently, or simultaneously, the telescopic parts 1 a and 1 bare extended from the outer part 1-in the direction shown by the arrow in Figure 3. Any suitable means may be used for extending the jib parts. When the parts have reached their extended positions, they are bolted together as indicated diagrammatically at 10. Alternatively, the foot end of the jib may be pivotally connected to the crane vehicle instead of connected to a pivotal footpiece. Operating mechanism on the crane vehicle is now operated to shorten the rope 8 and raise the A frame, thereby tightening the guy ropes. Further pivotal movement of the A frame raises the jib about its point of articulation on the crane vehicle into an operating position as shown in Figure 4. Further adjustment of the length of the ropes 8 raises or lowers the jibs as required. CLAIMS

1. A method of erecting the jib of a mobile crane, comprising transporting the jib into a position adjacent a crane vehicle, the parts of the jib being telescoped one within another during transportation, connecting the foot end of the jib to the crane vehicle, extending the parts of the jib and securing the extended parts together, connecting the guy ropes of the jib to a frame of the vehicle, and adjusting the inclination of the frame to raise the jib into its working position.

2. Ajib for a mobile crane comprising a plurality of telescopable parts capable of being secured one to another in an extended condition.

3. A jib according to claim 2, constituting an intermediate component between a foot piece and a head piece or other non-adjustable jib oarts.

4. Ajib according to claim 2 or claim 3, wherein mechanism for extending and retracting the telescoped parts comprise spindles, ropes, chains or the like.

5. A jib according to claim 2 or claim 3, wherein mechanism for extending and retracting the telescoped parts of the jib is hydraulic, comprising piston and cylinder units or the like.

6. Ajib according to any of claims 2 to 5, wherein the jib is transportable from site to site with guy ropes laid thereon.

7. A method for erecting a jib substantially as hereinbefore described.

8. Ajib substantially as hereinbefore described with reference to and as illustrated in the drawings.