... -hydraulic thrusters The thruster machine is mde of actuating motor and body(centrifugal pump),and boby has cover,jar,piston,wheel and ... piston,and forces the piston and the pole and beam fixed on piston to rise quickly,Compressing loading spring by lever ... (puller or brake attaching loading springs).(If natched with YWZ Series Hydraulic Puller,it will declutch).When it is cut offby electricity ...