transmission ring 110 if for example suitably high bias springs within centralizers 136 are used to engage balls 116 with transmission ring 110 even though electrohydraulic control unit 12 has been described with reference to actuating valve gate 32 of surface safety valve 18 it should be understood by one skilled in the art that electrohydraulic control unit 12 of the present invention is well suited for hydraulically actuating other devices when it is desirable to have a closed loop hydraulic system including but not limited to ball valves and choke valves for example as depicted in fig6 three electrohydraulic control units are operating at a well head installation that is generally designated 140 electrohydraulic control units 142 144 are respectively coupled to hydraulic actuators 146 148 hydraulic actuator 146 may be used to operate a crown valve while hydraulic actuator 148 may be used to operate a surface safety valve such as that discussed with reference to fig1 and 2 above electrohydraulic control unit 150 however is being used to control the actuation of subsurface safety valve 152 subsurface safety valve 152 is disposed in well production tubing 154 and may be several hundred feet below the ground surface subsurface safety valve 152 may utilize a flapper valve or a ball valve to shut in production through tubing 154 the operation of subsurface safety valve 152 is controlled by electrohydraulic control unit 150 via hydraulic control line 156 together electrohydraulic control unit 150 hydraulic control line 156 and the actuation device of subsurface safety valve 152 provide a closed loop hydraulic system which is suitably controlled by electrohydraulic control unit 150.