330B Excavator Hydraulic System Caterpillar

Adjust the pump output flow if the flow test results differ greatly from the specifications.

Adjustment Of Output Flow Under Total Horsepower Control

Illustration 1	g00364737
Pump compartment (23) Locknut (24) Setscrew (25) Locknut (26) Setscrew

Adjust the flow of the upper pump.

1. Loosen locknut (23) .

2. Turning setscrew (24) clockwise will increase the output flow of the pump. Turning setscrew (24) counterclockwise will decrease the output flow of the pump. A 1/4 turn of setscrew (24) will change the output flow of the pump at the following pressures.

   1. The pressure range of the first regulator spring is 17800 kPa (2600 psi) to 24700 kPa (3600 psi). Output flow of the pump will change approximately 23 L/min (6.1 US gpm) if the output flow is adjusted in this pressure range.

   2. The pressure range of the second regulator spring is 24700 kPa (3600 psi) to 34300 kPa (4950 psi). Output flow of the pump will change approximately 10 L/min (2.6 US gpm) if the output flow is adjusted in this pressure range.

3. Tighten locknut (23) to a torque of 12 ± 3 N·m (9 ± 2 lb ft).

4. Adjust the lower pump. Use locknut (25) and setscrew (26) instead of locknut (23) and setscrew (24) to adjust the lower pump. Repeat Steps 1 through 3.

Adjustment of the Maximum Output Flow of the Pump

Illustration 2	g00364739
Pump compartment (27) Locknut (28) Setscrew (29) Locknut (30) Setscrew

Adjust the maximum output flow of the upper pump.

1. Loosen locknut (27) .

2. In order to adjust maximum output flow, turn setscrew (28). Turning setscrew (28) clockwise will decrease the maximum output flow of the pump. Turning setscrew (28) counterclockwise will increase the maximum output flow of the pump. When setscrew (28) is turned by 90 degrees, the flow changes approximately 2 L/min (0.5 US gpm).

3. Tighten locknut (27) to a torque of 55 ± 10 N·m (41 ± 7 lb ft).

4. Adjust the maximum output flow of the lower pump. Use locknut (29) and setscrew (30) instead of locknut (27) and setscrew (28). Repeat Steps 1 through 3.