The check valves type RK/RB, RC, RE, and ER are used to block the flowin one direction and enable free flow in the opposite direction. The check valves type RK/RB are ball seated valves, where the valve element is spring loaded. They are sturdy and contamination tolerant due totheir design. The screw-in check valves type RC may be installed in both directions with the spring loaded valve shim enabling rapid switching sequences. There are also versions available featuring metric thread or a housing. The screw-in check valves type RE is a shim type check valve also butwithout spring pre-load. This enables a very compact and simple method of blocking the oil flow in one direction. This valve can be used as a "foot valve" in the suction pipe of pumps. The mounting hole for all screw-in checkvalves can be easily machined with a standard drill (point angle 118°). The check valve inserts type ER feature a ball seated design and are commonly installed in the ports of ball seated directional valves or other manifold mounted valves.