Reaction assembly for liquid pressure booster

A reaction assembly for a liquid pressure booster including a power piston slidably disposed in a housing and having a cylindrical section at its rear portion, a power chamber defined in the rear side of the power piston within the housing, an input shaft slidably extending into the housing through the rear side of the power piston, a control valve disposed across the cylindrical section of the power piston and the free end of the input shaft inside for supplying a liquid pressure to the power chamber which depends on an input applied to the input shaft, a reaction piston slidably disposed around the input shaft and responsive to a liquid pressure within the power chamber by being retracted relative to the input shaft for abutment against a stop formed on the input shaft, and a spring disposed between the power piston and the reaction piston for maintaining the reaction piston at an advanced position spaced from the stop with a given magnitude of resilience;

• characterized by
• a guide extending from the housing and projecting into the cylindrical section of the power piston, the reaction piston being slidably fitted in the guide which thus slidably supports the reaction piston, the reaction piston including a shank portion in which the input shaft is slidably fitted, thus allowing the input shaft to be slidably supported by the reaction piston;
• a first engaging portion formed on the reaction piston at a position forward of the guide and projecting radially outward within the cylindrical section of the power piston and reciprocable with respect to the power piston;
• a first stop formed on the cylindrical section of the power piston for restricting a rearward movement of the first engaging portion beyond a given stroke, the spring being disposed in a clearance formed between the outer periphery of the guide and the inner periphery of the cylindrical section of the power piston to act between the first engaging portion and the power piston;
• a second engaging portion formed on the input shaft to project radially outward within the reaction piston and reciprocable with respect to the reaction piston;
• and a second stop formed on the reaction piston for restricting a rearward movement of the second engaging portion beyond a given stroke.