GB191226279A - Improvements in or relating to Cranes and other Hoisting Apparatus. - Google Patents

Abstract

26,279. Variable Speed Gear, Ltd., and Robson, J. Nov. 15. Jib cranes. - Relates to cranes wherein one or more hydraulic motors are employed for effecting the various operations, the motors being worked from a pump which supplies pressure liquid to the motors at varying rates of flow. The pump and motor are preferably constituted by the pump and motor units of a variable hydraulic transmission gear. This may be of the kind having a cylinder barrel having a number of parallel cylinders for the reception of pistons provided with piston-rods pivotally connected to the pistons and to a plate carried by a tilting box, which in the case of a pump unit is displaceable to vary the direction and flow of the liquid. Fig. 1 shows the invention applied to a floating crane driven by one propeller and having a fixed jib. The prime mover A' is coupled to the pump A, from the valve plate of which pipes a, a<1> lead to distributing-valves a<Î>, a<Î>, from which pipes b, b<1> and c, c<1> are led to the valve plates of the motor units B, C respectively. The valves a<Î>, a<Î> are similar and are connected together to occupy similar positions. In Fig. 2, the valve a<Î> is shown in position for supplying fluid to the motor C" for hoisting, and in Fig. 3 to the propelling-motor B. The drums C<1>, C<2> are driven from the motor through suitable gearing for hoisting light and heavy loads respectively, a clutch c<2> being operated to clutch in either drum. A double-acting relief and by-pass valve is fitted between the suction and delivery pipes of the pump. The control is effected by operating the tilting box of the pump and the valves a<Î>, a<Î>. In a modification shown in Fig. 4, the floating crane is fitted with two propellers. In this case, two pump units A are driven by one or more prime movers A<1>. Pipes lead from the pumps to propelling and hoisting motors B, C. Two hoisting-drums C<1>, C<2> are provided as before and are driven through reducing-gearing so arranged that one or both motors may operate the drum C<2> for heavy loads, while one motor may be clutched to the drum C<1> for light loads. Equalizing-pipes A<3> connect the distributing and suction pipes and are fitted with stop-cocks A<3Î>. In a further modification, the floating crane has one propeller and a movable jib. In this case, one motor drives the hoisting-drum at two speeds through a clutch and spur gear while the other motor drives the drum for operating the jib. In a still further modification, there are two propelling-motors and a movable jib, two drums onlv being used. Specification 23,369/12 is referred to.