Patent GB-1009831-A (GB)
Title: An improved manual compensator for a hydraulic remote control system
Inventor: ROLLITT JOHN
IPC: F15B7/10
Filed: 1961-02-16
Abstract: 1,009,831. Hydraulic apparatus. ARMSTRONG PATENTS CO. Ltd. Jan. 31, 1962 [Feb. 16, 1961], No. 5767/61. Heading F1P. An hydraulic compensator 22, Fig. 1, for use in an hydraulic remote control system having double-acting transmitter and receive units 10, 14 connected by twin hydraulic lines 18, 20 comprises twin cylinder means 34, Fig. 2, each adapted for connection with one of the twin lines and each including a piston 36 displaceable between first and second positions to vary the total volume available to the hydraulic medium in the system, and common displacement means 48 acting on both of the pistons and operable by a single control member 46 for simultaneously displacing the pistons to identical extents. The control member consists of an eccentric which is mounted on a shaft 44 having a control lever and is received in the displacement means which is in the form of a block having projections 56 engaging the pistons. A rod 50 extends from the block and is engaged with a clearance fit in a bore 52 in the body 20 of the compensator to prevent substantial rotation of the block when the eccentric is rotated by the control lever to move the block and hence the pistons which are urged towards the block by springs 54. The interior 32 of the body serves as a reservoir of hydraulic fluid and each piston has a through passage 38, 40, Fig. 4, and a non-return valve 42 so that when the lever is operated to raise the pistons in their cylinders and the pressure below the pistons is sufficiently low, the valves can open to permit fluid in the reservoir to pass through the passages in the piston, passages 62 and outlets 58 to join the fluid in the twin lines 24, 26. If, because of a temperature rise, the pressure increases in the system as a result of the volume increase of the fluid, the control lever can be moved to raise the pistons to relieve the pressure. The lever is provided with a ratchet mechanism which maintains the pistons in their selected positions until released by manual operation. A longitudinal groove 64 is provided in the upper end of each cylinder so that if the increase in volume is greater than can be compensated for by movement of the pistons, the pistons can be by-passed when in their upper positions. A control valve is provided in a screw 102 intersecting the passages 62 to enable the passages to be interconnected whereby the arm 16 of the receiver unit can be synchronized with the actuator arm 12 of the transmitter unit. In an alternative embodiment, the pistons 37, Fig. 5, are disposed in sleeves 35 which are a press fit in the cylinders 34 and have stepped bores containing non-return valves consisting of balls 82 urged by springs 84 against seatings 86. In the event of a volume increase in the lines, the control shaft 44 can be rotated to cause the block 48 to move the pistons 37 downwardly, the movement causing rods 88 to lift the balls from their seats so that fluid can be vented from the lines through the valves and past labyrinth grooves in the pistons to the reservoir. The pistons can be held in a venting position by engagement of a stop 90 with the wall of the body 30. A volume contraction of fluid in the lines can be replenished by reciprocating the pistons to pass fluid through the valves to the lines.