GB457709A - Hydraulic controls for retractable undercarriages of aircraft - Google Patents

Abstract

457,709. Aircraft alighting gear. RUBBRA. A. A., Red Roofs, Carlton Road, Derby, and DOREY, R. N., Grasmere, Burton Road, Findern, near Derby. May 31, 1935, No. 15852. [Class 4] Means for raising and lowering the retractable alighting-gear of aircraft include one or more constantly - operating pumps A normally circulating fluid idly, one or more hydraulic rams C adapted to cause movement of the gear, a control D operating a valve B to govern the direction of fluid supply to the rams and means for holding the control and valve means in their displaced position during movement of the gear and returning them to the neutral position when the movement has ceased, thus positively locking the gear in position. When the control D is moved against one or other of spring plungers E it is caught by one or other of two catches pivoted on a pin E<5> carried by a plunger E<6> and integral with levers E<3> pivoted on shafts E<2>. The pin control can be released from the plunger, on actuation of a lever G<1> against the action of a spring G<2>. In the midposition of control D, oil from the pump is returned to a reservoir A<1> through a pipe A<3> and ports H, H<1>. On rotation of valve B port H is closed, pressure builds up under plunger E<6> which is raised against the action of a spring E<7> and raises the pin E<5> to cause one or other of the catches E<1> to engage the control D and hold it deflected ; simultaneously, port H<2> is opened to the fluid supply which passes through the valve to the ram C. When the ram reaches the end of its travel, the spring E<7> forces plunger E<6> downwardly, oil passing through the leakage aperture E<8> to release the control D which is then returned to its mid-position. In a modification, when the control D, Fig. 7, is moved, e.g. to the left, the right-hand plunger J<2> is moved against the action of its spring J<3> and the valve is rotated closing port K thereby causing oil to flow into port M. Oil passes to the ram through port M<1> and back to the reservoir through a port in the valve. When the ram reaches the end of its stroke, the compressed spring J<3> forces its ram to the left, oil leaking through the piston, and returns the control D.