GB1134156A - Crane boom jib assembly - Google Patents

Abstract

1,134,156. Mobile telescopic jib-cranes. GROVE MFG. CO. 1 May, 1967 [11 May, 1966], No. 20083/67. Heading B8B. A crane boom comprising an hydraulically extensible boom assembly 2 including a base section 2a, a mid-section 2b and a fly-section 2c is pivotally mounted at 3 to a pair of boom supports 4 carried by a turntable 5 mounted on a vehicle frame 6. A jib 1 is retained in stored position under the base section 2a by coupling means comprising a pair of fingers 23 and a finger 25 respectively engaging slots in lugs 22, 24. A releasable lock pin 26 holds the lug 24 on the finger 25 when the jib 1 is mounted in the stored position, a pair of flexible guy cables 27 for stabilizing the jib 1 in the operative position being retained by pins 20 when out of use. Removal of the pin 26 and transference of the pins 20 to apertures in bifurcations 19 enables the jib 1 to swing about a shaft 15 away from the base section 2a when the fly section 2c is extended to pull the lugs 22, 24 off the fingers 23, 25, respectively, the boom assembly being positioned transversely to the vehicle, Fig. 8 (not shown). The boom assembly is then swung to a position extending over the front of the vehicle and lowered to allow jib sheave assembly 18 to engage the ground (full lines in Fig. 9). The vehicle is then backed up until the jib 1 reaches the position shown in dotted lines in Fig. 9 when the hoist cable can be rigged through nose assembly 11. By taking up on the hoist cable winch hook assembly 32 engages the sheave assembly 18 to raise the free end of the jib 1 sufficiently to allow the cables 27 to be secured to shaft 16 (Fig. 10). The jib 1 is replaced in the stored position by reversing the above sequence of operations, except that the hoist cable 13 is looped over an arcuate shoe 34 and the end of the cable is secured to a hook anchor 33 to enable the jib 1 to be lifted up under the base section 2a.