Color-coded differential valve cartridge, used in underground water-hydraulic systems, includes valve- and control pistons with selective carrier assistance

摘要

The valve piston (78) and a control piston (76) are contained in the cartridge casing (72, 74), together with a piston spring (84). On the valve piston and/or the control piston, a carrier (90) is provided for the other piston. A colored marking is applied in a blind bore (95) of the valve cartridge. The carrier is designed to move the other piston in one direction but not in the opposite direction. The carrier is formed by an annular flange (90) on the control piston (76). The valve piston includes a projecting disc (92), its outer circumference matching the inner circumference of the annular flange. In an intermediate position of the control piston, a return flow opening (R) in the cartridge casing is fully closed, without sealing it off completely. The marking is provided by a colored plate (99). It is recessed into the cartridge, in a blind bore in part of its casing.