957, 725. Fluid-pressure servomotor systems. BORG-WARNER CORPORATION. Aug. 23, 1960 [Aug. 31, 1959], No. 29161/60. Heading G3P. A fluid-pressure servomotor system includes an electro responsive torque motor 29, a flapper 26 operated by the motor, a body 1, an elongated opening 12 in the body, shuttle means 41, a flexible seal 28 connected to the flapper and the body, mechanical feedback means 54, 55 between the shuttle and the flapper, a pair of nozzles 17, 21 respectively positioned at opposite sides of the flapper whereby movement of the flapper by the torque motor simultaneously and inversely varies the flow of fluid through the nozzles, passages 5, 6 to supply high pressure fluid to spaced portions of the opening 12, passages 7, 8 to supply lower pressure fluid to opposite end portions 13, 14 of the opening 12 and to nozzles 17, 21, and passages 56, 58 to supply high pressure fluid from the opening 12 to a controlled device 57 upon movement of the shuttle means. The seal 28 is a flexible diaphragm of berylium copper or spring steel. When the flapper 26 is pivoted anti-clockwise, for example, by the torque motor, pressure is increased in the nozzle 21 and in the space 14 to displace the shuttle means 41 to the left connecting the right hand side of the device 57 to the high pressure passage 6 and the left hand side to a sump port 25 through a passage 61. The feedback means 54, 55 consist of constant tension springs through which the shuttle means exert a linearly increasing force on the flapper to return it to a neutral position while the torque motor has two bifilar windings 29, 31 and a permanent magnet 40. A pressure port 4 supplies an opening 2 containing a ten micron filter 3 of sintered metal wire and communicating with the passages 7, 8 through restrictors 9, 11 which reduce the supply pressure from 3000 p.s.i. to about 300 to 700 p.s.i. To protect the flapper from impact forces due to fluid flow through the system, shields 46 and 51 are provided on the shuttle means.
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