Hartzell HC-D2MV20-3 Series Owner's Manual And Logbook page 125

(l) Install the jack plate unit and piston assembly on the
piston guide rods and against the flexible diaphragm.
NOTE:
CAUTION:
(m) Install a 0.37 to 0.50 inch (9.5 to 12.7 mm) inside
diameter (ID) flexible hose with a minimum pressure
capacity of 150 psi from the engine oil pressure
pump supply to the hydraulic valve. Connect the
hose to the threaded hole in the valve closest to the
propeller (the pressure supply port).
(n) Perform the following three adjustments:
1 Bottom the piston in the cylinder.
2 Pull the propeller control (for pitch and RPM
control) handle out approximately 2.25 inches
(57.1 mm) from the instrument panel.
3 Locate the valve spool midway between the
cotter pin and the base of the guide pin.
(o) Attach the propeller pitch control cable to the
hydraulic valve lever on the long end that extends
from the valve spool.
(2) Adjusting Travel on Hydraulic Unit Without Governor.
Refer to Figure 3-9.
(a) Remove the low pitch stop screw from the valve link.
(b) Loosen the screws to free the vernier control.
(c) Pull the piston out with the counterweights, until the
piston guide arms extend a maximum of 0.50 inch
(12.7 mm) for a 0.125 inch (3.17 mm) diaphragm or
a maximum of 0.44 inch (11.18 mm) for a 0.063 inch
(1.59 mm) diaphragm from the outer diaphragm ring
B-120.
INSTALLATION AND REMOVAL
Propeller Owner's Manual
Use a rubber mallet as necessary to
position the piston.
THE HOSE MUST BE LONG
ENOUGH TO ALLOW THE VALVE TO
MOVE FREELY WITH THE PISTON
THROUGH ITS FULL TRAVEL.
140
61-00-40
Rev. 3 Feb/14
Page 3-60.1