GB1346018A - Hydraulically operated crane with -dead man- actuated controls - Google Patents

Abstract

1346018 Jib cranes HARNISCHFEGER CORP 30 Oct 1972 [3 Nov 1971] 49905/72 Heading B8B [Also in Division F2] An hydraulically operated crane 10, Fig. 1, comprises a luffing boom 15 luffed by a boom hoist drum 34 through a boom hoist line 16 and front and rear load hoist drums 32, 33 used separately or jointly for hoisting operations through lines 35, 36. At least one of the drums is provided with a "dead man" actuated control (193), Fig. 7 (not shown), to stop rotation of the drum in the event that operator-controlled drive and brake to the drum are not engaged, the "dead man" actuated control being selectively placed in "off" and "on" positions. In the "off" position the "dead man" control is ineffective to alter operation of the control system of the crane and in the "on" position the "dead man" control acts to lock the drum in said event and prevents unsupervised free fall of the load. Figs. 3, 4, 5 show front load hoist drum 32 with clutch assembly 62 and brake assembly 63. A planetary gear assembly 64 allows a load to be lowered under controlled power and comprises a sun gear 70 attached to the drum 32 by bolts 71, 58. A spider ring 72 on bearing 73 is movable relative to the drum 32 and is provided with a braking surface 74 for brake bands (not shown). Spider ring 72 carries a pair of pins 75 mounting planetary gears 76 engaging the sun gear 70 and an outer gear 77 rigidly connected to hoist drum shaft gear 54 itself rigidly connected to drum shaft 51 rotated by engine (20), Fig. 2 (not shown), through shaft (300). The drum 32 is connected to the drum shaft 51 for rotation therewith by extension of a clutch cylinder 84 connected at 87 to a lever 81 pivoted at 82 and acting to expand a clutch band 83 against the inside of drum member 56. The drive is disconnected by a return spring 90 when the cylinder 84 is depressurized. A brake band 94 is contractable to engage main brake surface 60 of drum member 56 to stop the drum 32 by pressurization of cylinder 99 acting through link 96 pivoted at pin 97. The link 96 is biased clockwise by a fail-safe compression spring 98 and a cylinder 102 is provided to overcome, when energized, the bias of the spring 98 to release the brake band 94 to permit drum rotation.