The 5S5123 Hydraulic Testing Group is used to
make the pressure test of the hydraulic system. Before
any tests are made, visually inspect the complete
hydraulic system for leakage of oil and for parts that
have damage. For some of the tests, a timer and a
measuring rule (either for inches or for millimeters) are
WARNING: When testing and adjusting the
hydraulic system, move the machine to a smooth
horizontal location. Move away from machines that are at
work and any personnel. There must be only one
operator. Keep all other personnel either away from the
machine or where the operator can see the other
A visual inspection of the hydraulic system and its
components is the first step when a diagnosis of a
problem is made. Stop the engine, lower the bowl to the
ground and when the oil is cool so any pressure in the
tank will be at a minimum, make the inspections that
1. Measure the oil level. Slowly turn the filler cap until
it is loose to let the tank pressure lower before the filler
cap is removed. Look for air in the oil in the tank.
2. Remove the filter element and look for particles
removed from the oil by the filter element. A magnet will
separate ferrous particles from non-ferrous particles
(piston rings, O-ring seals, etc.).
3. Check all oil lines and connections for damage or
Checks of scraper operation can be used to find the
source of oil leakage in the hydraulic system. The oil in
temperature of 100° to 1200F (380 to 400C).
Drift of Bowl Cylinders
Check the drift of the bowl cylinders. Lift the bowl 6
to 10 in. (152 to 254 mm), then move the control lever to
the HOLD position. After three minutes, put a mark on
the side of the bowl at the bottom of the draft arm 6 in.
(152 mm) from the front of the bowl side. After five
minutes, make the measurement for drift. Drift on a new
machine is not more than .31 in. (7.9 mm).
If the drift is too much:
1. Check the carry check valves.
2. Check the piston seals in the bowl cylinders.
MEASURING DRIFT UOF BOWL CYLINPUEHR
Travel Time of Bowl Cylinders
Lower the bowl to the ground. Run the engine at high
idle rpm. Use a stop watch to find the time needed to
fully lift the bowl.
The time to lift the bowl from the ground to
maximum height is approximately 2 seconds.
If the travel time is not correct:
1. Check pump efficiency.
2. Check the settings of the relief valve for the bowl
and ejector circuits.
3. Check the operation of the bowl valve spool in the
control valve for the scraper.
4. Check the piston seals in the bowl cylinders.
Drift of Door Cylinder
The check valve for the door lets oil go to the ejector
cylinder and the door cylinder while the ejector moves.
The check valve keeps the door closed at the time the
bowl is loaded.
If the door opens during the load operation:
1. Check for dirt under the check valve.
2. Check for a broken valve spring in the check
3. Make sure valve moves freely in the valve body.
Travel Time of Ejector and Door
Lift the bowl approximately 6 in. (152 mm). Make
sure the door is closed. Run the engine at high idle.
Hold the ejector control lever in the FORWARD position.
Use a stop watch to find the time to fully open the door