Patent GB-1128017-A (GB)
Title: Telescopic booms
IPC: B66C23/697
Filed: 1965-09-29
Abstract: 1,128,017. Jib cranes. GROVE MFG. CO. 29 Sept., 1965 [8 April, 1965], No. 49055/67. Divided out of 1,128,016. Heading B8B. A crane boom 3, Fig. 2, comprises four sections 12. . . 15 telescopically disposed one in another, the sections 13, 14 being moved by telescopic hydraulic rams 43, 64, Fig. 4, and the section 15 being extended relative to the section 14 by means of an extension rod assembly 81, Figs. 10, 11, which after the sections 14 and 15 have been extended relative to the section 13 is connected between the section 15 and the section 13 to retain the section 15 stationary, while the section 14 is retracted. The boom 3 is pivoted at 4 to a housing 6 which includes a control cab 7 and is slewably mounted on a vehicle 1 having hydraulically extensible outriggers 2, hydraulic rams 9 being provided for pivoting the boom. Alternatively, the crane may be at a fixed location. It may have only three sections, the section 12 being omitted. The sections are of rectangular cross-section and the section 12 carries at its inner end a platform (27), Figs. 1 and 3 (not shown), for an hydraulically powered hoist winch (31), the platform being pivotable downwardly to give access to the end of the boom. Hoses (34) for the rams extend from the latter round a wheel rotatably mounted at the inner end of the boom to a spring-loaded reel (35). The section 13 has an upper housing 41 disposed within which is the ram 43. The section 15 is lockable in its extended or telescoped position to the outer end of section 14 by a pin 80, see also Fig. 8 (not shown), the pin being passed through apertures (58) in the section 14 and either of apertures 75, 76 in the section 15. A hoist cable 17 extends from the winch (31) along the boom to a nose assembly 16 on the section 15 and a hook assembly 18, the cable being guided along the boom by a channel 19 on the section 12, a drum on the section 13, and a loop 57 on the section 14. To facilitate movement of the sections relative to one another, the section 12 has roller bearings (38) for supporting the section 13 which has roller bearings 42 for engaging the section 12, and the section 13 has roller bearings 49 for supporting the section 14 which has roller bearings 69 for engaging the section 13. The section 14 has a hollow core 59 which extends inside the section 14 in spaced relation to the inner surfaces thereof, one end of the core being fixed to the inner end of the section 14 and the other end having skids 63 for sliding engagement with the section 15 when the latter is telescoped inside the section 14, the ram 64 extending within the core 59 between connections on the outer end of the core and the section 13. The rod assembly 81 comprises two sections 82, 83 and in use the section 82 is telescoped into the section 83 until stopped by a collar 84, and after the sections 14, 15 have been extended by the ram 64 the assembly is connected by means of clips 85, 86 thereon between a lug 74 on the section 15 and a bushing 87 on the section 13. The section 14 is then retracted by the ram 64, the section 15 remaining stationary and being thereafter locked by the pin 80 to the section 14. The ram 64 is again operated to extend both sections 14 and 15 and the assembly 81 drops away from the boom. The section 15 is retracted into the section 14 by actuating the winch (31) with the hook assembly 18 against the nose assembly 16.