Service Manual

Start-up & Maintenance
Fluids
Fluids used with Hydro-Gear products should be careful-
ly selected with assistance from a reputable supplier.
Typically, an API classification SG/CD engine oil is used
with a viscosity range equivalent to
20W50.
Start-up Procedure
The following start-up procedure should always be fol-
lowed when starting a new installatiin or when restarting
an installation in which the BDP had been removed from
the system.
-
Prior to starting the BDP, make certain all system com-
ponents (reservoir, fittings, etc.) are clean prior to filling
with fluid.
Be certain to fill the BDP housing with clean fluid
prior
to start-up. Fill the housing by pouring filtered oil
into the upper case drain
port, if possible.
Fill the reservoirwith
recommended fluid which should be
filtered prior to entering the reservoir.
The inlet line and filter leading from the reservoir to the
charge pump must
be filled prior to start-up. Check inlet
line for properly tightened fittings and make sure it is free
of restrictions and air
leaks.
Pressurizing the inlet 2-4 PSI will aid in start-up. "Jog" or
slowly rotate the engine with the swashplate in its neutral
(0 angle) position until charge pressure starts to rise
(charge pressure is defined as
low side loop pressure).
Start the engine and run at the lowest possible RPM.
With the bypass valve closed, slowly move the displace-
ment control in both the forward and reverse directions.
As air is purged from the unit, the oil level in the reservoir
will drop and bubbles may appear in the fluid. Refill the
reservoir
as necessary.
Place thedisplacement control in the neutral position and
open the bypass valve. Slowly move the displacement
control in both the forward and reverse directions to
purge the air from the closed circuit.
Close the bypass valve and run the unit in both directions
for several minutes until any remaining air is purged from
the unit.
Refill the reservoir as necessary.
Shut down the engine, check for and correct any fluid
leaks, and check the reservoir level. Add fluid
if neces-
sary. The transmission is now ready for operation.
Maintenance
Check the reservoir daily for proper fluid level, the
presence of water (noted by a cloudy to milky appear-
ance,
or free water in bottom of reservoir), and rancid
fluid odor (indicating excessive heat).
The BDP-1
0L units normally do not require regular fluid
changes. The system filter should be changed per the
vehicle/machine manufacturer's recommendations. The
fluid and fitter should
be changed and the system cleaned
if the fluid becomes contaminated with foreign matter
(water, dirt, grease, etc.) or if the fluid has been subjected
to temperature levels greater than the maximum recom-
mended.
Page 4 BDP Service Manual