1,197,344. Fluidic logic. T. W. HAMILTON. 16 Jan., 1969 [11 March, 1968], No. 11341/68. Heading G4P. [Also in Division F2] A double pilot pneumatic slide valve for e.g. pneumatic logic systems comprises a housing (Figs. 1, 2) of blocks 1, 2, 3 bolted together; the block 1 of transparent perspex having a semicylindrical valve chamber in which semicylindrical member 7 is laterally movable with its flat bottom face sliding over the flat top face of block 2. Semicylindrical shoulders 10, 11 at the end of recess 6 limit the slider movement, and semicircular sealing O rings 12 are located in grooves of the recess. Air ports at each end of the recess comprise drillings 14, 15; 18, 19 and grooves 17, 21, while registering blind bores 16, 20 retain visible rubber telltale discs 22, 23 raised by the entry of air into the pilot ports. An inlet bore joins a groove 27 in the upper face of block 3, and an outlet bore joins a groove 29, while first and second cylinder bores join grooves 31, 33. Groove 23 joins air inlet bore 34, groove 29 joins exhaust bore 35, and grooves 31, 33 join blind bores 36, 37 communicating with slots 38, 39 in the sliding face of block 2. The slider face is formed with transverse grooves 42, 43, 44 and axial grooves 40, 41; groove 43 being connected to vertical bore 45. In operation, the inlet is supplied with pressure air, the exhaust is vented, and the cylinder bores are connected to the ends of a pneumatic ram (not shown) controlled by the valve. Ports 14, 18 are supplied with control pressures, to move the slider to its alternate positions. In one case, pressure air enters space 46 through bores 34, 35 to hold the slider firmly to block 2, and through grooves 40, 43 and slot 38 to pressure one end of the ram cylinder, whose other end is vented over slot 39, grooves 41, 42 and bore 35. In the other case, the one end of the ram cylinder is vented over slot 38, grooves 41, 44 and bore 35 while the other end is pressurized over grooves 43, 40 and bore 34; the slider remaining pressed against block 2. The valve may be assembled to a pneumatic logic system by fixing block 3 to a base-plate ported to register with the bores and located by asymmetrical pin 47.