349F and 352F Excavators Hydraulic System Pump Control (Output Flow) - Adjust Caterpillar


Pump Control (Output Flow) - Adjust
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1.1. Introduction
2.1. Adjustment Procedure
3.2. Adjustment of Pump Output Flow (Constant Horsepower Control)
4.2. Adjustment of the Maximum Output Flow of the Pump

Introduction

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

Adjustment Procedure

Table 1
Approximate Change of Flow with 1/4 Turn of Adjustment Screw 
Adjustment Screw  1/4 Turn of Adjustment Screw  Torque for Locknut 
First Stage of Constant Horsepower Control  33 L/min (8.7 US gpm)  160 ± 24 N·m (120 ± 18 lb ft) 
Second Stage of Constant Horsepower Control  16.7 L/min (4.4 US gpm)  16 ± 2.4 N·m (12 ± 1.8 lb ft) 
Maximum Output Flow  7.4 L/min (2.0 US gpm)  240 ± 36 N·m (175 ± 27 lb ft) 

Adjustment of Pump Output Flow (Constant Horsepower Control)



Illustration 1g01368631
Main pump compartment
(1) Adjustment screw (second stage)
(2) Locknut
(3) Adjustment screw (first stage)
(4) Locknut
(5) Adjustment screw (second stage)
(6) Locknut
(7) Adjustment screw (first stage)
(8) Locknut

Adjust the flow of the drive pump for the first stage of the constant horsepower control. The idler pump must be at no-load condition.

  1. Loosen locknut (4).

  2. Turn adjustment screw (3) in order to adjust the output flow of the pump. Turning adjustment screw (3) clockwise will increase the output flow of the pump. Turning adjustment screw (3) counterclockwise will decrease the output flow of the pump. A 1/4 turn of adjustment screw (3) will change the output flow of the pump at the following pressure.

    • Output flow of the pump will change approximately 33 L/min (8.7 US gpm) if the output flow is adjusted in the pressure range of 10000 kPa (1450 psi) to 21000 kPa (3050 psi). The pump is operating in the first stage of the constant horsepower control.

  3. Tighten locknut (4) to a torque of 160 ± 24 N·m (120 ± 18 lb ft).

Adjust the flow of the drive pump for the second stage of the constant horsepower control. The idler pump must be at no-load condition.

  1. Loosen locknut (2).

  2. Turn adjustment screw (1) in order to adjust the output flow of the pump. Turning adjustment screw (1) clockwise will increase the output flow of the pump. Turning adjustment screw (1) counterclockwise will decrease the output flow of the pump. A 1/4 turn of adjustment screw (1) will change the output flow of the pump at the following pressure.

    • Output flow of the pump will change approximately 16.7 L/min (4.4 US gpm) if the output flow is adjusted in the pressure range of 28000 kPa (4050 psi) to 31000 kPa (4500 psi). The pump is operating in the second stage of the constant horsepower control.

  3. Tighten locknut (1) to a torque of 19 ± 2.8 N·m (14.0 ± 2.1 lb ft).

Adjust the idler pump in the same manner as the drive pump. Use locknut (8) and adjustment screw (7) in order to adjust the first stage of the constant horsepower control. Use locknut (6) and adjustment screw (5) in order to adjust the second stage of the constant horsepower control.

Adjustment of the Maximum Output Flow of the Pump

Note: Adjustment screws for maximum output flow for both the drive pump and the idler pump are located on the back side of the pumps.



Illustration 2g02149358
Top view of main pump compartment
(9) Adjustment screw (maximum output)
(10) Locknut
(11) Locknut
(12) Adjustment screw (maximum output)
(13) Idler pump regulator
(14) Drive pump regulator
(15) Pump delivery lines

Adjust the maximum output flow of the drive pump.

  1. Loosen locknut (11).

  2. In order to adjust maximum output flow, turn adjustment screw (12). Turning adjustment screw (12) clockwise will decrease the maximum output flow of the pump. Turning adjustment screw (12) counterclockwise will increase the maximum output flow of the pump. A 1/4 turn of adjustment screw (12) will change the maximum output flow approximately 7.4 L/min (2.0 US gpm).

  3. Tighten locknut (11) to a torque of 240 ± 36 N·m (175 ± 27 lb ft).

Adjust the maximum output flow of the idler pump in the same manner as the drive pump. Use locknut (10) and adjustment screw (9) in order to adjust the maximum output flow of the idler pump.

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