Bendix Commercial Vehicle Systems C-300N HYDRAULIC POWER STEERING1/99 - Manual (Page 8)

8
BYPASS VALVE OPERATION
The optional bypass valve is located adjacent to the pressure
relief valve in the valve body.
When it is necessary to steer the vehicle without the power
steering pump in operation, the bypass valve permits oil to
flow from the return to the supply passages within the
steering gear. As the power piston moves inside the housing,
oil displaced from one side is transferred to the other through
the bypass valve thus preventing reservoir flooding and
cavitation in the pressure line. Figure 9
POWER STEERING GEAR IDENTIFICATION
A nameplate is attached to the exterior of the housing
generally on one of the mounting lugs. The information found
on the name tag is illustrated
PREVENTIVE MAINTENANCE
POWER STEERING OIL
It is important that an approved oil be used to ensure proper
operation of the power steering unit. The vehicle
manufacturer’s recommendations should be adhered to.
Once an oil type is in use, it should never be mixed with any
other type. If it should become necessary to change types
of oil, the entire system must be drained following the
procedure below.
DRAINING AND FILLING THE SYSTEM
1. Lift the front axle sufficiently to raise the wheels clear of
the ground.
2. Remove the drain plug (54) and seal washer(53) or
disconnect the return line at the valve body outlet port.
(The outlet port is identified by the arrow which flows out
of the gear.) Turn the steering wheel to the left as far as
it will go. Run the engine for 10 seconds at the most
until the oil is drained from the reservoir and pump. Switch
off the engine and turn the steering wheel backwards
and forwards from full lock to full lock until all the oil is
drained out.
3. Clean the outside of the reservoir. Remove and replace
the old filter element.
4. Fill reservoir full of oil.
5. Turn the engine over with the starter motor. (Must be
done in a manner that the engine does not start.) Add oil
as the level drops to avoid air being drawn into the
system.
6. When the oil level reaches the full mark on the dipstick,
start the engine and turn the steering wheel slowly from
side to side until air bubbles cease to appear in the
reservoir. Refill reservoir to full mark on the dipstick.
7. The oil level should be checked every 2,000 miles. The
correct level is between the minimum and maximum level
marks on the dipstick with the engine stopped.
OIL CHANGE INTERVALS
It is recommended that the oil be changed at 40,000 mile
intervals and at the time of rebuild. Beyond its function as
the media for transmitting power, the oil also serves to
lubricate and dissipate heat. Carefully clean, inspect, and
replace if necessary all filter elements in the pump system
including vents and breathers.
OUTPUT SHAFT SECTOR TEETH
ADJUSTMENT
The gear lash or preload between the piston teeth and sector
gear should not require attention in normal service, however
a provision for adjustment is provided.
Adjustment requires that the steering gear be drained and
the pitman arm and input shaft be disconnected from the
vehicle. The adjustment procedure is described at the end
of the assembly section of this manual.
POWER STEERING GEAR NAMEPLATE INFORMATION
SERIAL NUMBER
BENDIX ASSEMBLY
PART NUMBER
MONTH ASSEMBLED
(A = JAN., ETC.
VEHICLE
MFG’R
PART
NUMBER
LOCATION OF
MANUFACTURE
YEAR ASSEMBLED
(LAST DIGIT)
FIGURE 9 - BYPASS VALVE OPERATION
INPUT
SHAFT OIL
RETURN
CHANNEL
POWER
STEERING
GEAR
HOUSING VALVE
BODY
SPRING
BYPASS
VALVE
OIL SUPPLY
PORT
OIL RETURN
PORT