16-21.PISTON PUMP - REPAIR (Contd)
a. If removed, install locating pin
(12) in valve block (3).
The side of the wafer plate with the
locating pin groove must face the valve
b. Assemble wafer plate (11) over
bearing race (48) and plate
groove over locating pin (12).
Wafer plate (11) must be flat against
valve block face. Check to make sure it
does not rock back and forth. If
rocking motion occurs, make sure
locating pin (12) is bottomed out in
the valve block (3).Wafer plate
rocking will induce high stress
conditions and cause fractures in the
c. Place valve block (3) on its
side. Install piston rod (8) into
valve block (3) and attach
retaining ring (47).
d. Install new O-ring (46) in the
piston rod (8) O-ring groove.
Be careful not to allow the piston to
drop from piston rod as this could
damage the piston.
e. Install piston (7) over piston
f. Assemble valve block (3) to
housing (6) with six screws (9).
g. Cross tighten screws (9) to bring
valve block and housing evenly
together against gasket (10).
Torque screws (9) to 60-70