TM 5-3810-307-24-1-2
4.4
Filter Change
Together with the main inspection *) the filter cartridges in single or multi-chamber oil tank should
also be replaced. When pulling out the used-up filter cartridges keep lower bore closed to make
sure that the used oil from the filter cartridge is not running back into the tank or entering the oil
circuit. Lubricate filter carrier prior to inserting cartridge.
4.5
Filling-in and Venting
4.5.1
Filling-in
NOTE
During the subsequent procedure make particularly sure that the oil tank
is not sucked empty, since otherwise new air bubbles will again and again
enter the steering system. Also make sure while filling-in and while
venting, that the engine and drive-dependent pumps are operating at the
lowest possible speed (idle speed with gear step engaged and drive axle
for drive-dependent pump jacked up). If the suction current is too high,
small air bubbles would again be sucked in in direction of the pumps and
would be torn into tiny particles when running through the pumps, which
may lead to foaming and then make the venting process
disproportionately long.
Under influence of different installation conditions for our power steering gear and power cylinders
there may be a case in which the steering system in a given vehicle model cannot be completely
vented quickly enough and that the share of the air remaining in the power cylinders will be
removed gradually only. In such a case we recommend loosening the connection between the
power cylinders and the vehicle components on piston side so that the entire piston stroke from
stop to stop in power cylinder can be used for venting.
This will reduce the air remaining in the cylinder to a minimum. This air has no influence on driving
and is automatically absorbed by the oil while driving and discharged. The steering system and the
pumps are filled through the filler neck on single or multi-chamber oil tank. For initial filling and for
an oil change it will be of advantage to remove the tank cover and to fill in hydraulic oil up to edge of
tank. Then, with a gear step engaged (drive axle for drive-dependent pump jacked up), crank
engine several times with the starter motor to fill the entire hydraulic system with oil. Since the oil
level in tank will drop quickly during this process, keep adding oil to make sure that the pumps are
not sucking in air.
4.5.2
Bleeding the System
Once the steering system has been filled to the extent that the oil level no longer drops beneath the
upper mark on the oil dipstick, allow the engine to run at low speed for a period (if a drive-
dependent is fitted, with driven wheels raised clear of the ground and gear engaged), during which
time most of the air will be expelled from the cylinder chambers. Observe the oil level during this
process. If the level sinks, replenish the supply immediately. To accelerate the bleeding procedure,
it is advisable to turn the steering wheel several times from stop to stop with the steered wheels
raised clear of the ground. With full lock applied, do not apply more force to the steering wheel than
is required to turn the steering. If necessary, add oil until the level remains constant at the upper
mark on the dipstick and air bubbles cease to appear in the tank when the steering wheel is turned
from lock to lock.
*)
Minor deviations are permitted, if desired by vehicle manufacturer, to include the intervals into vehicle
maintenance schedule.
Change-1 H-17
