Patent GB-651202-A (GB)
Title: Improvements in or relating to tractor-mounted cranes
IPC: B66C23/36
Filed: 1947-06-25
Abstract: 651,202. Jib cranes; load-handling machines. HYSTER CO. June 25, 1947, No. 16748. Convention date, Nov. 1, 1945. [Class 78 (iv)] [Also in Groups XXI and XXXII] A tractor-mounted crane comprising a cranemast and back-stay assembly mounted on a tractor of the type having endless track units flexibly mounted on opposite sides of its body is characterized in that the assembly comprises a mast mounted to swing about a transverse horizontal axis adjacent one end of the body and rigid back-stay struts connected to the upper end of the mast and anchored to the endless track units at points spaced from the mast along the tractor. The tractor body 11 is pivoted by the driving-axle 12 to the frames 13 of endless track units 14 and is supported at its forward end by a leaf-spring 15 connected at 16 to the frames 13. The two-legged mast 23 of the crane is pivoted at 24 to upstanding brackets 21 on the tractor body and is held upright by stays 25 pivoted at their lower ends to brackets 22 upstanding from the frames 13. At their upper ends the stays 25 are pivoted at the outer ends of a beam 30 which is centrally pivoted to a guide-member 29 on the mast-head 27, and which is locked to the member 29 when the crane is in use to prevent relative movement of the body 11 and track unit 14. To permit adjustment so that the body 11 is level when the front ends of the track units 14 are at different levels, the yokes 68 (Fig. 13) by which the stays 25 are connected to the beam 30 adjustably telescope within the stays 25, being locked in position by pins 69. Further, the beam 30 may be locked at several angles relatively to the mast 23 by a locking device on the masthead 27 operated by a handle 74 to engage teeth 66 formed on the beam 30. As shown in Fig. 16 a member 70 on the same shaft 73 as the handle 74 carries a projection 71 adapted to engage between two of the teeth 66 to lock the beam 30, and further projections 72 which, when the shaft 73 is rotated through one half-revolution, engage on either side of one of the teeth to lock the beam in a different position. In intermediate positions of the shaft 73 the beam 30 pivots freely. To assemble the crane on the tractor the stays 25 with beam 30 are first secured to the brackets 22 which may be semi-permanent fixtures, and are supported by struts 35 resting on lugs 34 on the brackets 21 (see Figs. 1 and 5). A portable winch is then suspended from the beam 30 and is used to raise the lower ends of the mast 23 to be pinned to the brackets 21. A winch 38 on the mast 23 is then used as shown in Fig. 5 to raise the mast, a guide-plate 60 guiding the beam 30 into position for insertion of the pin about which it pivots. The portable winch 36 (Fig. 8) is then suspended from the mast 23 and is used, firstly to raise a hoist unit comprising a turntable 41, platform 42, crane operator's seat 43 and controls 44 into position on the tractor, and then, as shown in Fig. 8, to connect the boom 50 by pins 55 to the turntable 41. A joint 49 in the boom is first broken and the end of the lower section 51 is raised by the winch 36 to be temporarily pivoted at 52 to the turntable 41, then the winch 36 is employed to raise the boom to the position shown in broken lines in Fig. 8, after which it may be connected at 55 to the turn-table and raised by means of its suspension cable 54. A bulldozer on the front of the tractor may serve as a counterweight or brackets may be provided on the frames 13 of the track units for holding balancing weights as described in Specification 592,499, which is referred to. The masthead may be externally guyed. The crane may be rigged for dragline scraper operation employing a sheave 57 and fair-leads 58 (Fig. 8) on the boom 50.