Symmetric balanced type. The frame and crosshead guide are of integral structure. The crankshaft has no oil holes and is fitted with an integral connecting flange for rigid direct coupling. Bolts for crankshaft and connecting rod joints are hydraulically tightened. The crosshead is equipped with removable slippers with adjusting shims. The piston rod is connected to the crosshead via hydraulic tightening tools. Fitted with the HRCS stepless capacity regulation system, the compressor enables stepless capacity adjustment ranging from 20% to 100%.