320B Excavator Hydraulic System Caterpillar

Illustration 1	g00518284
Flow meter tool layout (1) Swing motor (2) Connector (top of swing motor) (3) 6V-9840 Swivel tee (4) Makeup line (swing motor) (7) Negative flow control line (front pump) (8) 6V-9508 Plug (12) 4C-9910 Portable hydraulic tester (flow meter) (15) Delivery line for rear pump (16) Delivery line for front pump (18) Front pump (20) Negative flow control line (rear pump) (22) Rear pump (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 assembly (38) 8C-9026 Adapter (39) 6K-6307 O-ring seal (40) 9S-8004 O-ring plug (42) 6V-8397 O-ring seal (47) 3J-1907 O-ring seal (48) 1U-8303 Fitting (49) 8T-4184 Bolt (50) 8T-4223 Hard washer (51) 6V-0400 Half flange (53) 1U-8292 Adapter (54) 1P-3703 Rectangular seal (55) 9U-7335 Blocking cover (59) 6V-9854 Swivel elbow

Illustration 2	g00519297
Circuit diagram (1) Swing motor (2) Connector (top of swing motor) (3) Tee (4) Makeup line (5) Main control valves (6) Test hose (7) Negative flow control line (front pump) (8) Plug (9) Pressure tap (front pump delivery pressure) (10) Pressure gauge (11) Pilot oil manifold (12) Portable hydraulic tester (flow meter) (13) Pressure tap (pilot oil manifold) (15) Delivery line (rear pump) (16) Delivery line (front pump) (18) Front pump (19) Pressure gauge (20) Negative flow control line (rear pump) (21) Pressure tap (rear pump delivery pressure) (22) Rear pump (23) Multitach group (24) Engine (46) Tee (55) Blocking cover (59) Swivel elbow

Front Pump

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

Illustration 3	g00543131
Pump compartment (7) Negative flow control line (front pump) (9) Pressure tap (front pump delivery pressure) (16) Delivery line (front pump) (18) Front pump (22) Rear pump

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 circuit diagram. Refer to Illustration 2.

   1. Disconnect delivery line (16) from front pump (18) .

   2. Install seal (54), half flanges (51) and blocking cover (55) to the end of delivery line (16) by using bolts (49) and washers (50) .

   3. Assemble and install seal (54), adapter (53), seal (52), fitting (29), seal (47), plug (40), seal (34) and nipple assembly (36) on the outlet port of the front pump by using half flanges (51), bolts (49) and washers (50) .
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   Illustration 4	g00344499
   Swing motor (top view) (1) Swing motor (2) Connector (4) Makeup line

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

   5. Assemble and install seals (30), tee (3), swivel elbow (59), coupling (37), seal (34) and nipple assembly (36) to connector (2) at the top of swing motor (1) .

   6. Connect makeup line (4) to tee (3) .

   7. Connect portable hydraulic tester (12) between nipple assembly (36) at front pump (18) and nipple assembly (36) at the swing motor.

   8. Connect 60000 kPa (8700 psi) pressure gauge (10) to pressure tap (9) for front pump delivery pressure.

   9. Install multitach group (23) on engine (24). This is used to monitor engine speed.

   10. Disconnect negative flow control line (7) from front pump (18). Install plug (8) and seal (42) to the end of negative flow control line (7) .
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   Illustration 5	g00518376
   Tool setup (9) Pressure tap (front pump delivery pressure) (10) 8T-0861 Pressure gauge (11) Pilot oil manifold (13) Pressure tap (pilot oil manifold) (19) 8T-0855 Pressure gauge (21) Pressure tap (rear pump delivery pressure) (25) Pilot relief valve (41) 6V-9829 Cap (42) 6V-8397 O-ring seal (43) 6V-3989 Unvalved nipple (44) 6V-4143 Coupler assembly (45) 6V-3014 Hose (46) 8T-8902 Tee (47) 3J-1907 O-ring seal (56) 6V-3965 Nipple assembly (57) Negative flow signal pressure port (front pump) (58) Negative flow signal pressure port (rear pump)

   11. Assemble and install seals (42), tees (46), cap (41), seals (47) and nipple assemblies (56) to the negative flow signal pressure port (57) of front pump (18) .

   12. Connect one end of test hose (45) to tee (46). Refer to Illustration 2.

   13. Connect the other end of test hose (45) to pressure tap (13) of pilot oil manifold (11) .

   14. Connect a 6000 kPa (870 psi) pressure gauge (19) to tee (46) .

Rear Pump

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

Illustration 6	g00543262
Pump compartment (15) Delivery line (rear pump) (18) Front pump (20) Negative flow control line (rear pump) (21) Pressure tap (rear pump delivery pressure) (22) Rear pump

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 circuit diagram. Refer to Illustration 2.

   1. Disconnect delivery line (15) from rear pump (22) .

   2. Install seal (54), half flanges (51) and blocking cover (55) to the end of delivery line (15) by using bolts (49) and washers (50) .

   3. Assemble and install seal (54), adapter (53), seal (52), fitting (29), seal (47), plug (40), seal (34) and nipple assembly (36) on the outlet port of the rear pump by using half flanges (51), bolts (49) and washers (50) .
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   Illustration 7	g00344499
   Swing motor (top view) (1) Swing motor (2) Connector (4) Makeup line

   4. Disconnect makeup line (4) from swing motor (1) .

   5. Assemble and install seals (30), tee (3), swivel elbow (59), coupling (37), seal (34) and nipple assembly (36) to connector (2) at the top of swing motor (1) .

   6. Connect makeup line (4) to tee (3) .

   7. Connect portable hydraulic tester (12) between nipple assembly (36) at rear pump (22) and nipple assembly (36) at the swing motor.

   8. Connect 60000 kPa (8700 psi) pressure gauge (10) to pressure tap (21) for rear pump delivery pressure.

   9. Install multitach group (23) on engine (24). This is used to monitor engine speed.

   10. Disconnect negative flow control line (20) from rear pump (22). Install plug (8) and seal (42) to the end of negative flow control line (20) .
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   Illustration 8	g00518376
   Tool setup (9) Pressure tap (front pump delivery pressure) (10) 8T-0861 Pressure gauge (11) Pilot oil manifold (13) Pressure tap (pilot oil manifold) (19) 8T-0855 Pressure gauge (21) Pressure tap (rear pump delivery pressure) (25) Pilot relief valve (41) 6V-9829 Cap (42) 6V-8397 O-ring seal (43) 6V-3989 Unvalved nipple (44) 6V-4143 Coupler assembly (45) 6V-3014 Hose (46) 8T-8902 Tee (47) 3J-1907 O-ring seal (56) 6V-3965 Nipple assembly (57) Negative flow signal pressure port (front pump) (58) Negative flow signal pressure port (rear pump)

   11. Assemble and install seals (42), tees (46), cap (41), seals (47) and nipple assemblies (56) to the negative flow signal pressure port (58) of rear pump (22) .

   12. Connect one end of test hose (45) to tee (46). Refer to Illustration 2.

   13. Connect the other end of test hose (45) to pressure tap (13) of pilot oil manifold (11) .

   14. Connect a 6000 kPa (870 psi) pressure gauge (19) to tee (46) .

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: Power Mode, engine speed dial "10" and AEC switch OFF. Make reference to Testing And Adjusting, "Operational Checks" for engine rpm settings.

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

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Illustration 9	g00344497
Pilot oil manifold (11) Pilot oil manifold (13) Pressure tap (25) Pilot relief valve

4. Adjust pilot relief valve (25) on pilot oil manifold (11) until pressure gauge (19) that is connected to tee (46) is 2350 kPa (340 psi).

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Illustration 10	g00344501
Portable hydraulic tester (flow meter) (12) Portable hydraulic tester (flow meter) (23) Multitach (26) Valve

5. Turn valve (26) on portable hydraulic tester (12) clockwise until the pump delivery pressure is 6850 kPa (1000 psi).

6. Record the negative flow in Table 1.

Illustration 11	g00535259
P-Q characteristic curve

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

Flow measurements must be done in pressure rise.