Patent GB-1028301-A (GB)
Title: Pneumatic analogue computer
IPC: G06G5/00
Filed: 1962-12-03
Abstract: 1,028,301. Fluid pressure servomotor system analogue computers. GARRETT CORPORATION. Dec. 3,1962 [Dec. 4,1961], No. 45663/62. Heading G3P. A fluid pressure analogue computor adaptable for performing various computations comprises a housing 21 containing carriages 26 slidable along guides 27, 28 and carrying pressure responsive diaphragms 52 which urge rollers 47 against a lever 22 which has a fixed pivotal mounting 23. In addition to the four carriages 26 shown, four further carriages also coacting with the lever 22 are provided in a parallel plane behind those shown. Parallel with each set of guides 27, 28 is an adjusting screw (not shown) and each carriage has a member that can be brought into engagement with such screw whereby each carriage may be adjusted  along the lever 22 by rotation of the screw. When a carriage has been so adjusted it is disengaged from the screw and clamped to the guides. One or more of the carriages, as shown the upper and lower, left-hand carriages A, B which are strapped together by a member 136, may be adjusted by a unit 30 comprising a servopiston 90 sealed by diaphragms 91, 94 and controlled by a ball valve assembly 118 actuated by a lever 119 subject to the actions of a pressure responsive diaphragm assembly 112,113 and a feedback spring 102 connected to the servopiston. A ball valve assembly 43 similar to the assembly 118 is actuated by one end of the lever 22 and supplies a signal to one of the carriages to rebalance the lever 22 after it has been deflected. This assembly comprises balls 76, Fig. 5 (not shown) movable in a bore 74 having pressure supply openings 80 at each end, a central exhaust opening 85 and annular output ports 77. Initial adjustment of the balls is effected by a screw 71 entering a tapered bore in the bifurcated end 70 of the lever 22. In the case of the assembly 118 the two output ports are connected to opposite sides of the servopiston 90, but in the assembly 43 only one output port is used at one time depending upon whether an increased or decreased output pressure is required from movement of the lever 22 in a given direction. A resistance-capacitance unit 31 comprising a capillary tube 123 in series with a chamber 125 bounded by a spring-loaded diaphragm 126 may be employed in computations involving integration and differentiation. The apparatus may be connected as in Fig. 10 (not shown) for producing an output pressure Po which is a function of the difference between a pressure P3 and the sum of two pressures P 1  and P 2 . In this arrangement neither the servopiston 90 nor the resistance-capacitance unit 31 is used, and the output pressure from the assembly 43 is fed to the upper, left-hand carriage 26 to balance the moments exerted by the other carriages. Fig. 11 (not shown) the apparatus set up for multiplication, the output pressure P 0 which is fed to the upper carriage 26 being a function of the product of a pressure P 1  supplied to the lower carriage 26 and a pressure P 2  which, through the unit 30, determines the position of the lower carriage along the lever 22. For obtaining an output P o  as a function of the time differential of a pressure P 1  the arrangement of Fig. 16 (not shown) is employed in which the pressure P 1  is fed directly to the lower, left-hand carriage 26 and through the resistance 123 and capacitance C to the lower, right-hand carriage. Other arrangements for performing division, compound multiplication and division, integration and extracting square roots are described. Successive computations may be performed by arrangements of apparatus in cascade. The input fluid pressure signals may be derived from electrical signals, and the output may be converted to an electrical signal.