TM 5-3805-260-24
The setting of the relief valve for maximum pressure
must be according to the Service Manual.
CAUTION: When the pressures are higher than 1000
psi, slowly open the manual load valve before turning
the steering wheel back to center. This will prevent
possible damage to the pressure gauge.
Test 2: System Oil Temperature
1. Open the manual load valve fully.
2. Turn the steering wheel to the RIGHT TURN
position.
3. Write down the oil temperature.
Test 3: System Base Flow Rate
1. Open the manual load valve fully.
2. Turn the steering wheel to the RIGHT TURN
position.
3. Run the engine at test rpm.
4. Check pressure to make sure it is at a minimum
valve of approximately 100 psi.
5. Write down the flow rate (gpm). The base flow
rate of the system will be the same as the low pressure
flow of the hydraulic pump. Because there will be
minimum leakage in the control valves, lines and
cylinder packings at 100 psi, the base flow rate can be
used to find the flow differential in Tests 4 and 5.
NOTE: If the base flow rate (Test 3) is less than the flow
rate in Test 4, do Test 4 first and then Test 3. For vane
pumps only, this takes place when the vanes in the
pump do not have full extension at low pressure.
Tests 4 and 5: Leakage Rates
These two tests are similar. Each test is done as
follows:
1. Move the steering wheel to the respective TURN
positions.
2. Run the engine at test rpm.
3. Make an adjustment to the manual load valve to
get 1000 psi pressure.
4. Make the system constant with these conditions.
5. Write down the flow rate (gpm) for each test. The
flow differential for each test (4 and 5) is found by taking
the flow rate for each test away from the base flow rate
(Test 3). The percent of flow loss for each test (4 and 5)
is found by dividing the flow differential for each test by
the base flow rate (Test 3).
Test 10: System Oil Temperature
1. Open the manual load valve fully.
2. Turn the steering wheel to the RIGHT TURN
position.
3. Write down the oil temperature.
Make a comparison of the oil temperature from Tests 2
and 10. Test 2 must be 150 5
F and Test 10 must be
inside of (within) 10
F of Test 2. For each 10 F higher
difference (Test 10 higher than Test 2), take away .5
gallon per pump cartridge from the leakage rate. For
each 10
F lower difference, add .5 gallon per pump
cartridge to the leakage rate.
Is It Necessary To Make More Tests?
If so, Which Circuit(s)?
Make a comparison of the test data with the data on
Chart A for the specific machine under test. The percent
of flow loss on Chart A is maximum for best
performance.
Components that are worn, or not working correctly, are
found by their flow differential and percent of flow loss or
lower system efficiency. System values for new and
rebuilt machines must not be more than the percent of
flow loss in the system tests shown on Chart A for the
specific machine. The permissible flow differential is a
function of machine application. For applications with
low travel speeds, the permissible flow differential can
be more than for applications with high travel speeds.
If the percent of flow loss is acceptable, the Tee Test is
completed.
If the percent of flow loss is not acceptable, the tests for
the pump and/or the blocked cylinders must be done.
Troubleshooting
The following examples are a list of problems and
probable reasons. They will aid in finding the
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