Patent GB-576074-A (GB)
Title: Improvements in or relating to hydraulic motors
IPC: F03C1/28
Filed: 1944-02-02
Abstract: 576,074. Liquid - pressure engines; fluid - pressure servomotors. GUNNING, M. F. Feb. 2, 1944, Nos. 1919, 2864, 16467 and 19595. [Classes 69 (ii) and 135] In a multi-cylinder hydraulic motor for operating winches, lifts, &c. in ships, the cylinders are arranged in groups of three or more, the cylinders of one group being of lesser diameter and means being provided for energizing one or more of the groups. The cylinders of an 18-cylinder engine are arranged in groups of 3, 6 and 9 disposed around and parallel to a driven shaft carrying one or two cams against which rollers, carried by cross-heads operated by the pistons, abut the 3-group cylinders are of smaller diameter. Springs may be disposed between the pistons and cross-heads. A distributing valve (Figs. 1-7, not shown), rotated by the engine, has three axial positions of adjustment in which it supplies liquid to the 3-group, the 3 and 6 groups or all groups respectively. Reversal is effected by rotary adjustment of the valve. Another control arrangement comprises a main control valve p, Fig. 8, supplying a rotary distributing valve q having connections direct to the 3-group and through selector valves p<2>, p<3>, to the 6 and 9 groups respectively. The main control valve also supplies a distributing valve reversing cylinder r<2>, and a cylinder s, for closing manually-operable valves s<2>, s<3>, controlling pressure supply for operating the selector valves p<2>, p<3>. The 3-group may thus be used alone or in combination with the 6 or 9 groups, or all cylinders may operate together. A further arrangement (Fig. 12, not shown), provides a manually-operable main control and reversing valve supply two rotary distributing valves, one of which controls the 3-group and the other through selector valves the 6 and 9 groups. In this arrangement, if the load should tend to run back, the back pressure created by the 3-group moves a safety valve against supply pressure and causes a brake to be applied. In yet another arrangement, Fig. 13, a control and reversing valve u supplies rotary distributing valves u', u<2>, of which the former is connected direct to the 3-group and the latter, through selector valves u<3>, u<4>, to the 6 and 9 groups. When a load is being lowered, the 6 and 9 groups circulate liquid in a closed path through the control valve u which can be used as a throttle to regulate speed. The 3-group also discharges into the circuit to maintain a minimum pressure determined by relief valve w<4>. If the load is too great for the 3-group, the back pressure rises and opens a valve x<1>, thereby applying pressure to a cylinder u<8> to raise the main control valve and bring the distributing valve u2 into operation. At the same time a cylinder g<1> is actuated to move valves u<5>, u<6> and open both selector valves u<3>, u<4> to bring the 6 and 9 groups 'into operation. Alternatively, when valve x<1> opens, pressure is applied to a brake cylinder w<11>. The rotary distributing valve shown in Fig. 14 comprises helical grooves v<5>, v<6> connected alternately to annular inlet and exhaust grooves v<9>, v<10>. The main control valve p, Fig. 8, may be operated by a hand wheel through a hunting gear driven from the engine (Fig. 16, not shown). In this case, the motor will rotate only so long as the hand wheel is being turned, since if this is stopped the motor returns the valve to the position, cutting off pressure supply. The first Provisional Specification describes also a construction in which flow to the cylinders is controlled by a rotary distributing valve in contact with the cylinder block. Selection of the cylinder groups is effected by valves in the supply to the distributer actuated by cams on a shaft set manually. Motor speed is controlled by a separate valve.