Conversion of an existing mRoy A or B pump from micrometer knob capacity adjustment to electric capacity control
requires removal of certain parts from the pump and actuator as well as calibration adjustments. No machining is
Remove the end plug (402-B) and replace with the new mounting stud furnished separately with the actuator.
This plug must be tightened flush or slightly below the machined surface with the special tool provided.
Do not use Teflon tape on mounting stud threads as Teflon debris may enter the hydraulic system of the
pump. An oil-resistant pipe compound should be used instead.
Rotate the micrometer control knob (255) to the zero capacity setting.
Pry the E-ring (404) from the control spool (268-B) groove located against the face of the control knob.
Unscrew the control knob.
Be careful to maintain the control spool location.
Remove the small screw (256) that enters through the threaded sleeve (243). Using pliers, rotate the sleeve to
break the Loctite bond, then remove the sleeve.
Remove all Loctite residue from the extension to assure a proper moisture seal by the actuator housing O-ring.
Remove the two screws (405-C) holding the cover on the electric capacity control actuator and remove the
cover. Remove the 1/4-20 screw from the microswitch mounting plate (284-A) and let the plate hang free.
Assemble the actuator over the pilot extension on the pump housing, carefully guiding it over the control spool
extension. The actuator must slide over the pilot far enough to allow the mounting faces to meet without
changing the zero position of the control spool. Assemble the seal washer (408-A) and nut over the mounting
stud with rubber side of washer toward pump. Tighten securely.