1998/05/25 Caterpillar


New Main Pump Group Creates New Specifications For Service Manual Module SENR8961 {5050,0372}

Usage:


325B L (2JR1639-Up) Excavators

Reference: Service Manual Module; Testing And Adjusting 325B and 325B L Excavators Hydraulic Systems; SENR8961; "Pump Flow Test And Adjustment"; Page 24. This module is found in Service Manual SENR8955.

New pump flow test specifications are required for the machines listed. The additions to the service manual module are as follows:

On Page 27, for the "Test Procedure"; the P-Q Characteristic Curve and the Delivery Pressure Chart on Page 28 contains new specifications. Make the following additions to the module.


P-Q Characteristic Curve

On Page 29, for the "Main Pump Flow Adjustment", Subsection "Flow Control", Step 2 contains new specifications. Make the following additions to the module.

2. Adjust the flow by turning setscrew (24). When setscrew (24) is turned clockwise, the flow increases. When the screw is turned counterclockwise, the flow decreases. When setscrew (24) is turned 1/4 turn, the flow changes as follows:

a. It is approximately 22 liter/min (5.8 U.S. gpm) within a control range of regulator first spring [measured pressure points 15 000 kPa (2200 psi) and 23 400 kPa (3400 psi)].

b. It is approximately 8.5 liter/min (2.2 U.S. gpm) within a control range of regulator second spring [measured pressure points 23 400 kPa (3400 psi) and 34 300 kPa (4950 psi)].

On Page 34, for the "Test Procedure"; the P-Q Characteristic Curve and the Negative Flow Control Pressure Chart contains new specifications. Make the following additions to the module.


P-Q Characteristic Curve [Negative Flow Control at 6850 kPa (1000 psi) Pump Delivery Pressure]

On Page 35, for the "Negative Flow Control Adjustment"; Step 2 contains new specifications. Make the following additions to the module.

2. Turn setscrew (27) until adjusted to the correct specification.

Turning setscrew (27) clockwise decreases the flow rate. Turning the setscrew (27) counterclockwise increases the flow rate by the same amount as shown in the clockwise rotation. A quarter turn of setscrew (27) changes the flow rate as follows:

a. Approximately 2 liter/min (0.5 U.S. gpm) at system pressure of 2450 kPa (355 psi).

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