589,453. Shock-absorbers. VANDERVELL PRODUCTS, Ltd., and JOHNSON, E. W. March 12,1945, No. 6163. [Class 108 (iii)] In a double-acting shock-absorber in which a restricted passage for the flow of damping fluid in both directions between two fluid containers 28, 29 is provided between the opposed surfaces of a metering rod 94 and a bore 32 into which the rod 94 reaches and in which a bye-pass is provided through the interior of the rod 94, travel of fluid through the bye-pass in each direction is controlled respectively by one of two valves 115, 116, operated by the pressure of the fluid. In the construction shown in Fig. 1, the metering rod 94 passes through a sleeve 32 located in the main piston the heads 30, 31 of which reciprocate respectively in the containers 28, 29. A conduit 112 permits fluid to pass in both directions between the container 29 and the interior of the rod 94 and conduits 113, 114 in the opposite end of the rod 94 co-operate with the valves 115, 116 to control the flow of fluid respectively to and from the container 28. The valve 115 is slidable upon the valve 116, a single spring 117 urging both valves into a position to isolate the conduits 113, 114 from the container 28. A predetermined pressure in the container 28 uncovers the port 114 by acting against the right-hand end surface of the valve 116 which is designed to have greater area than its area exposed to pressure from the opposite direction. A predetermined pressure in the container 29 acts through conduits 112, 113 against the end wall of a recess 120 in the valve 115 to open the conduit 113 to the container 28. The valve 116 has longitudinal clearance grooves 119 to prevent turbulence and both valves may have their bores enlarged in the region of their associated conduits so that full flow will occur with a minimum valve opening thereby avoiding valve chatter. In a second construction the metering rod 94 is mounted in a separate casing formed in the wall of the casting of the main casing each end of which is connected by respective passages to the containers 28, 29. In a third construction, a separate spring is employed for each of the valves 115, 116. Fluid in the containers 28, 29 is replenished from a recuperator chamber 16 through ball-valve-controlled passages 121, 122 which are arranged at right angles to the surfaces of the coned inner portions of the piston heads 30, 31 in such manner that each of these passages can be drilled through from the open end of the recess in the piston head. Each ball 123 is retained in its passage by a forcefitted castellated bush 125, and tends to fall by gravity on to its conical seat. The general construction is similar to that described in Specification 548,011. Specifications 541,179 and 541,201 also are referred to.