Service Manual

14
BDP-10A/16A/21L
FLUID VOLUME AND LEVEL
Certain situations may require additional fluid to
be added or even replaced. Refer to the vehicle
manufacturer’s recommendations for the proper
fill location and level. After maintenance or oil
change, follow purging procedures below and re-
check the fluid level once the unit has been oper-
ated for approximately 1 minute.
FLUID CHANGE
In the event of oil contamination or degradation,
oil addition or change may alleviate certain per-
formance problems. Refer to the vehicle
manufacturer’s recommended oil change fre-
quency. Refer to purging procedures below.
FILTERS
An inlet filter is required to insure that only clean
fluid enters the system. Refer to the vehicle manu-
facture for approved filter replacement.
The following procedures should be performed
with the vehicle drive wheels off the ground, then
repeated under normal operating conditions.
WARNING
POTENTIAL FOR SERIOUS INJURY
Certain procedures require the vehicle
engine to be operated and the vehicle to
be raised off of the ground. To prevent
possible injury to the servicing techni-
cian and/or bystanders, insure the ve-
hicle is properly secured.
1. With the bypass valve open and the engine
running, slowly move the directional control
in both forward and reverse directions (5 to 6
times), as air is purged from the unit, the oil
level will drop.
2. With the bypass valve closed and the engine
running, slowly move the directional control
in both forward and reverse directions (5 to 6
times). Check the oil level, and add oil as re-
quired after stopping engine.
3. It may be necessary to repeat Steps 1 and 2
until all the air is completely purged from the
system. When the BDP’s move forward and
reverse at normal speed purging is complete.
Cleanliness is a key factor in the successful re-
pair of BDP’s. Thoroughly clean all exposed
surfaces prior to any type of maintenance. Clean-
ing of all parts by using a solvent wash and air
drying is usually adequate. As with any preci-
sion equipment, all parts must be kept free of
foreign material and chemicals. Protect all ex-
posed sealing areas and open cavities from dam-
age and foreign material.
Upon removal, all seals, O-rings, and gaskets
should be replaced. During installation, lightly
lubricate all seals, O-rings, gaskets with clean
petroleum jelly prior to assembly. Also protect
the inner diameter of seals by covering the shaft
machined features with plastic wrap or equiva-
lent.
PURGING PROCEDURES
Due to the effects air has on efficiency in hydro-
static drive applications, it is critical that air is
purged from the system.
These purge procedures should be imple-
mented anytime a hydrostatic system has been
opened to facilitate maintenance or any addi-
tional oil has been added to the system.
Air creates inefficiency because it has compres-
sion and expansion rates that are higher than
that of oil.
Entrained air in the oil may cause the following
symptoms:
1. Noisy operation
2. Lack of power or drive after short-term op-
eration
3. High operation temperature and excessive
expansion of oil.
Before starting, make sure the reservoir is at the
proper oil level. If it is not, fill to the vehicle
manufacturer’s specifications.