Chain drive tensioner spring force control mechanism

A tensioner for a passive tensioner system for tensioning a chain span or a belt, comprising:

• a housing having a cylindrical bore;
• an external piston comprising a head connected to a shaft, the head having a top surface and a bottom surface and the shaft having a bottom surface;
• a hollow moveable sleeve received by the cylindrical bore of the housing, comprising a hollow body having a first end with an inner flange, a second end, and an interior with an inner diameter, the inner flange having a top surface and a bottom surface;
• the external piston and the hollow moveable sleeve being coaxially arranged within the cylindrical bore of the housing;
• a hollow fixed sleeve received by the cylindrical bore and the hollow moveable sleeve and receiving the shaft of the external piston;
• an external piston spring for biasing the external piston outwards from the housing, the external piston spring having a first end contacting the bottom surface of the head of the external piston and a second end contacting the top surface of the inner flange of the hollow moveable sleeve;
• a sleeve spring received within the cylindrical bore of the housing and in contact with the hollow moveable sleeve for biasing the hollow moveable sleeve outwards from the housing;
• a first hydraulic chamber formed by the cylindrical bore of the housing, the hollow moveable sleeve, and the fixed sleeve having a first fluid input;
• and
• a second hydraulic chamber formed by the cylindrical bore of the housing, the fixed sleeve, and the shaft of the external piston, with a second fluid input, such that an inward force acting to push the external piston into the housing creates a fluid pressure in the second hydraulic chamber, causing the hollow moveable sleeve to exert an outward force on the external piston through the external piston spring, opposing the inward force.