A variable capacity rotary screw compressor having a rotor housing including a bore, an inlet, an outlet, a slide valve recess and rotors. Passive and active slide valves are mounted in the recess. Individual passive and active slide valve balancing units are connected to the passive and active slide...http://www.google.se/patents/US5183395?utm_source=gb-gplus-sharePatent US5183395 - Compressor slide valve control
