325C Excavator Hydraulic System Main Pump (Flow) - Test - Constant Horsepower Flow Control Caterpillar

This test measures individual pump flow at the pump. Each pump is tested individually for output flow at specified pressures. The pump that is not being tested is not under load and the pump remains at low pressure standby.

Illustration 1	g00817116
The electronic control module is located in the compartment behind the cab. (1) Alarm lamp (2) Electronic control module

Illustration 2	g00671482
(3) Monitor (4) Message display

Note: Before starting main pump flow tests, check message display (4) on monitor (3) and alarm lamp (1) on electronic control module (2) for normal operation. Lamp (1) should be green. If no faults are present, perform the operational checks. Refer to Testing and Adjusting, "Operational Checks".

Note: If the operational checks indicate that slow speed of an implement is common to the circuits of one pump, the problem is most likely in the hydraulic system. Then perform the pump flow tests. Refer to Testing and Adjusting, "Piston Pump (Main) - Test".

Note: If the operational checks indicate that slow speed of an implement is common to both pump circuits, the problem may be in the engine, the fuel, or the working altitude.

Illustration 3	g00671496
Flow meter tool layout (1) Swing motor (2) Connector at swing motor (3) 6V-9840 Swivel tee (4) Makeup line (swing motor) (6) Negative flow control line (right pump) (10) 4C-9910 Portable hydraulic tester (flow meter) (11) Delivery line (left pump) (12) Delivery line (right pump) (13) Negative flow control line (left pump) (17) 9U-7335 Blocking cover (23) Right pump (24) Left pump (29) 1U-8303 Fitting (30) 5K-9090 O-Ring seal (31) 5P-0201 Hose (32) 5P-1010 Sleeve (33) 4C-8767 Coupling (34) 7M-8485 O-Ring seal (35) 4C-6481 Coupler assembly (36) 4C-6482 Nipple assembly (37) 4I-6141 Coupling (38) 8C-9026 Adapter (39) 6K-6307 O-Ring seal (40) 6V-9854 Swivel elbow (42) 1P-3703 Rectangular seal (46) 8T-4184 Bolt (47) 8T-4223 Hard washer (48) 6V-0400 Half flange (49) 1U-8292 Adapter

Illustration 4	g00817191
Circuit diagram (1) Swing motor (2) Connector (3) Tee (4) Makeup line (5) Main control valve (8) Pressure tap (left pump delivery pressure) (9) 8T-0861 Pressure gauge (10) 4C-9910 Portable hydraulic tester (flow meter) (11) Delivery line for left pump (12) Delivery line from right pump (16) Pressure tap (right pump delivery pressure) (17) 9U-7335 Blocking cover (20) 8T-0856 Pressure gauge (21) Engine (22) Multitach (23) Right pump (24) Left pump (40) Elbow (50) Pressure tap (power shift pressure)

Right Pump

Note: Perform the test for the right pump and the test for the left pump one at a time.

Illustration 5	g00817197
Pump compartment (8) Pressure tap (left pump delivery pressure) (12) Delivery line for right pump (16) Pressure tap (right pump delivery pressure) (23) Right pump (24) Left pump (50) Pressure tap (power shift pressure)

1. Position the machine on level ground.

2. Stop the engine.

3. Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release".

4. Install the following tools in accordance with the flow meter tool layout and the circuit diagram. Refer to Illustration 3 and Illustration 4.

   1. Disconnect delivery line (12) from right pump (23) .

   2. Install seal (42), half flanges (48) and blocking cover (17) to the end of delivery line (12) by using bolts (46) and washers (47) .

   3. Assemble and install seal (42), adapter (49), seals (34), fitting (29) and nipple assembly (36) on right pump (23) by using half flanges (48), bolts (46) and washers (47) .
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   Illustration 6	g00669270
   Swing motor (top view) (1) Swing motor (2) Connector (3) Tee (4) Makeup line (40) Elbow

   4. Disconnect makeup line (4) from connector (2) at swing motor (1) .

   5. Assemble and install seals (30), tee (3), swivel elbow (40) and coupling (37) to connector (2) at swing motor (1) .

   6. Install seal (30) and makeup line (4) to tee (3) .

   7. Connect portable hydraulic tester (10) and the test hoses between nipple assembly (36) at right pump (23) and coupling (37) at the swing motor.

   8. Connect 4900 kPa (700 psi) pressure gauge (20) to tap (50) for power shift pressure. Connect 49000 kPa (7100 psi) pressure gauge (9) to tap (16) for right pump delivery pressure.

   9. Install multitach group (22) on engine (21). This is used to monitor engine speed.

Left Pump

Note: Perform the test for the right pump and the test for the left pump one at a time.

Illustration 7	g00817210
Pump compartment (8) Pressure tap (left pump delivery pressure) (11) Delivery line for left pump (16) Pressure tap (right pump delivery pressure) (23) Right pump (24) Left pump (50) Pressure tap (power shift pressure)

1. Position the machine on level ground.

2. Stop the engine.

3. Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release".

4. Install the following tools in accordance with the flow meter tool layout and the circuit diagram. Refer to Illustration 3 and Illustration 4.

   1. Disconnect delivery line (11) from left pump (24) .

   2. Install seal (42), half flanges (48) and blocking cover (17) to the end of delivery line (11) by using bolts (46) and washers (47) .

   3. Assemble and install seal (42), adapter (49), seals (34), fitting (29) and nipple assembly (36) on left pump (24) by using half flanges (48), bolts (46) and washers (47) .
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   Illustration 8	g00669270
   Swing motor (top view) (1) Swing motor (2) Connector (3) Tee (4) Makeup line (40) Elbow

   4. Disconnect makeup line (4) from connector (2) at swing motor (1) .

   5. Assemble and install seals (30), tee (3), swivel elbow (40) and coupling (37) to connector (2) at swing motor (1) .

   6. Install seal (30) and makeup line (4) to tee (3) .

   7. Connect portable hydraulic tester (10) and the test hoses between nipple assembly (36) at right pump (23) and coupling (37) at the swing motor.

   8. Connect 4900 kPa (700 psi) pressure gauge (20) to pressure tap (50) for power shift pressure. Connect 49000 kPa (7100 psi) pressure gauge (9) to pressure tap (8) for left pump delivery pressure.

   9. Install multitach group (22) on engine (21). This is used to monitor engine speed.

Test

Note: Perform the test for the front pump and the test for the rear pump one at a time.

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To prevent personal injury or equipment damage from failure of the hydraulic test equipment or associated circuit components because of blocked pump flow, make sure that the test equipment valves are fully open before starting the engine.

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To prevent personal injury and/or equipment damage from failed lines or components while the hydraulic test equipment is returned to the open flow position, slowly open the hydraulic test equipment valve while monitoring the pump flow. If pump flow does not increase as the valve is opened, shut the engine off and determine what is preventing the pump from upstroking.

1. Start the engine.

2. Place the machine controls at the following settings: engine speed dial "10" and AEC switch OFF. Refer to Testing and Adjusting, "Engine Performance - Test" for engine rpm settings.

3. Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).

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Illustration 9	g00672009
Monitor (A) Message display (B) Keypad (C) Up key (D) Left key (E) Down key (F) Right key (G) Cancel key (H) Set key (I) OK key (J) Menu key

4. Start Service Mode and input a fixed power shift pressure of 2400 ± 50 kPa (350 ± 7 psi).

   1. Press menu key (J) .

      Note: If more than thirty seconds pass between pushing the keys on the keypad, the menu mode will be cancelled and the previous display will be restored to message display (A) .

   2. Press down key (E) in order to highlight the menu item "SERVICE OPTIONS" on the message display. Press OK key (I) .

   3. Input the password "FFF2". Press left key (D) or right key (F) in order to change the position of the flashing character. Press up key (C) or press down key (E) in order to change the value of the flashing character. Press OK key (I) after the correct password is displayed.

   4. Press down key (E) once in order to highlight the second line on the message display.

   5. Press right key (F) repeatedly until "DEVICE TEST" appears on the message display.

   6. Press down key (E) in order to move down one line on the message display.

   7. Press right key (F) until the "PS PRV - FIXED" appears on the message display.

   8. Press down key (E) .

   9. Press OK key (I). The display on line 4 of the message display will now change to a numeric value. These characters represent the power shift pressure (kPa).

   10. Press left key (D) or right key (F) in order to increase or decrease the numeric value that is displayed on line 4 of the message display. Pressing left key (D) one time decreases the power shift pressure 10 kPa (1.5 psi). Pressing right key (F) one time increases the power shift pressure 10 kPa (1.5 psi).

       Note: The value for power shift pressure on the monitor may not always match the pressure reading on the pressure gauge. Adjust the value on the monitor until the desired power shift pressure is attained on the pressure gauge that is connected to the pressure tap for power shift pressure. The actual power shift pressure must be 2400 ± 50 kPa (350 ± 7 psi) on the pressure gauge.

       Note: To prevent a change in power shift pressure during the pump flow test, do not turn the engine start switch to the OFF position.

       Note: Refer to Service Manual, "Engine and Pump Electronic Control System" for additional information on Service Mode.

5. In order to perform flow measurements for either one of the pumps, the other pump must not be under load.

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Illustration 10	g00670500
Portable hydraulic tester (flow meter) (10) Portable hydraulic tester (flow meter) (22) Multitach (26) Valve

6. Turn valve (26) on portable hydraulic tester (10) clockwise. Record pump flow at each of the following pressures in Table 1. Use pressure gauge (9) at pressure tap (16) to monitor right pump delivery pressure or use pressure tap (8) to monitor left pump delivery pressure.

Illustration 11	g00817128
P-Q characteristic curve

Note: Specifications for output flow rates are based on an engine speed of 1800 rpm. To attain more accurate test results, measured flow should be corrected with the following calculation.

Note: Specifications for output flow rates are based on a power shift pressure at the pump of 2400 ± 50 kPa (350 ± 7 psi). The output flow rate changes approximately 7 L/min (1.8 US gpm) for each 100 kPa (14 psi) of power shift pressure in the lower range of the constant horsepower control. The output flow rate changes approximately 3 L/min (0.8 US gpm) for each 100 kPa (14 psi) of power shift pressure in the higher range of the constant horsepower control.

Note: If the output flow rate of the pump is not within the specification, disconnect the negative flow control line from the pump that is being tested and perform the test again.

Note: Flow measurements must be done only during pressure rise.