GB577947A - Improvements in or relating to fluid jack or like devices - Google Patents

Abstract

577,947. Hydraulic machines. AUTOMOTIVE PRODUCTS CO., Ltd., and PARKER, S. M. Dec. 15, 1941, No. 16181. [Class 69 (ii)] [Also in Group XXVIII] Fluid pressure jacks for use on aircraft for operating flaps, bomb doors, retractable undercarriages, &c. are locked in extended or retracted positions by means of locking-devices mounted externally of the cylinder and operable by fluid pressure to release the locking device. As shown in Figs. 1 and 2, a hollow ram 14 is mounted in a cylinder 10 provided with heads 12, 13 with inlets for fluid pressure. The ram 14 is fitted with a pin 21 which is engaged by a spring-controlled locking device in the form of a pivoted half-sleeve 19 having a notch 20 for engaging the pin in the retracted position of the ram 14. The ram is moved to this position by fluid admitted to the head 13 acting upon a piston 33 to which the ram is connected by a pin 31 and slot 32. Within the ram is a rod 30 secured to the piston, and a pin 28 on this rod moves a cam 27 free of a pin 25 of the catch when the ram is fully withdrawn and permits the locking-device to engage the pin 21. When pressure is applied to the cylinder head 12 the ram cannot move until the piston 33 moves to the right and causes the cam 27 to free the locking-device, so that the device remains locked until fluid pressure is applied. In a modification, Fig. 5, a hollow ram 40 provided with a piston 42 co-operates with a cylinder 41 and toggle links 50, 51 are used to connect a sleeve 45 on the cylinder 41 with a cross-head 48 connected to the ram. When the jack,is extended to the position shown in Fig. 5, the toggles move so as to be past the dead-centre position and springs 52 maintain them in this position so that pressure on the piston 42 can not move the ram which is held in locked position until the toggle is moved outwards past the dead-centre position by the action of rollers 55 on a sliding sleeve 54 upon cam blocks 53 connected to the links 50. The sleeve 54 is connected by a rod 58 to a piston 59 slidable in the ram 40 and subjected to fluid pressure in the jack. It is necessary for the rollers to break the toggle before the jack can be operated either when it is in the expanded position shown or in the retracted position in which the links 51 are operated to draw the sleeve 45 towards the cross-head 48. In a further modification the locking-device comprises a longitudinally split sleeve having an annular shoulder adapted to engage with a corresponding shoulder for locking purposes, and means for producing radial distortion of the split sleeve for separating the said shoulders and releasing the lock.