311B and 312B Excavators Hydraulic System Caterpillar

Illustration 1	g00381292
Rear pump (13) Setscrew (14) Locknut

Note: Use the same procedure for both pumps. Use locknut (14) and setscrew (13) for the rear pump adjustment. Use locknut (16) and setscrew (15) for the front pump adjustment.

1. In order to adjust the rear pump, loosen locknut (14).

2. Turn setscrew (13) until the negative flow rate is adjusted to the correct specification.

   Note: A clockwise adjustment of setscrew (13) and setscrew (15) increases the flow rate. A counterclockwise adjustment decreases the flow rate. A quarter turn of setscrew (13) and setscrew (15) will change the flow rate approximately 7.1 L/min (1.9 US gpm) at a system pressure of 2350 kPa (340 psi).

3. Tighten locknut (14) to the specified torque.
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   Illustration 2	g00381353
   Front pump (drive end) (15) Setscrew (16) Locknut

4. Adjust the front pump. Use locknut (16) and setscrew (15) instead of locknut (14) and setscrew (13) to adjust the front pump.