Piper Aircraft Corporation Cherokee 140 PA-28-140, Service Manual

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PIPER CHEROKEE SERVICE MANUAL
VI - HYDRAULIC SYSTEM 01/31/08
2D12
6-9. TEST AND ADJUSTMENT OF HYDRAULIC PUMP. (Refer to Figure 6-4.)
a. Test Equipment:
1. Hydraulic pump and mounting base.
2. Pressure gauge (0 to 1000 psi).
3. Pressure gauge (0 to 3000 psi).
4. Hoses with fittings to connect between base and gauges.
5. Power supply (14V DC).
6. Ammeter (0 to 100 amps).
7. Fuse or circuit protector (100 amp).
b. Test and Adjustment:
1. Connect a 0 to 1000 psi gauge to the low pressure port (port No. 3) of the pump base. (The low
pressure port, No. 3, is located nearest to the pipe plug installed in the base.)
2. Connect a 0 to 3000 psi gauge to the high pressure port (port No. 1) of the pump base. (The
high pressure port, No. 1, is located farthest from the pipe plug installed in the base.)
3. Connect the black lead of the pump motor to the negative terminal of the DC power supply.
4. Fill the pump reservoir and bleed all air from the attached lines. (Lines may be bled by
alternately connecting the blue electrical lead and green lead to the positive terminal of the
power supply until all air is exhausted.)
5. Connect the blue lead to the positive terminal of the power supply. Pump should operate and
the high pressure gauge should indicate between 1600 to 2000 psi. (Should the pressure be
incorrect, adjust valve “A”, Figure 6-3, in pump reservoir.)
6. Disconnect the blue lead, and the high pressure reading should not drop more than 300 psi in
five minutes. High pressure may not be selected until after five minutes.
7. Connect the green lead to the positive terminal of the power supply. Pump should operate in
reverse, dropping the high pressure gauge to zero and the low pressure gauge should indicate
between 500 to 800 psi. When the green lead is disconnected, both pressure gauges should
indicate zero psi. (Should the pressure of 500 to 800 psi be incorrect, adjust valve “B”, Figure
6-3, in pump reservoir.)
NOTE: During test steps (5) thru (7), there should not be any external leakage.
8. Should it be necessary to check the pump motor, first connect the ammeter in the electrical
circuit with the positive terminal of the meter to the black lead and the negative terminal of the
meter to negative terminal of the DC power supply.
9. Connect the blue lead to the positive terminal of the power supply. With the high pressure
indication within the 1600 to 2000 psi range on the pressure gauge, the ammeter should read
between 35 to 60 amperes. Disconnect the electrical lead.
10. Connect the green lead to the positive terminal of the power supply. With the high pressure
indication within the 500 to 800 psi range, the ammeter should read between 15 to 35 amperes.
NOTE: In the event that any of the various tests do not perform satisfactorily, the pump
assembly should be overhauled or replaced.
11. Connect the green lead to the power supply to drop pressures before disconnecting the
hydraulic lines.