Governor Instability Caterpillar

Governor Instability

Usage:

EXCAVATORS320B (4NR, 5BR, 9KR, 8ES, 4XW),
320B L (6CR, 1DS, 1ES, 5GW),
320B LL (6LS, 9JS) EXCAVATORS

Problem:

Some of these excavators, particularly those that have accumulated many hours of operation, may develop governor instability or surging.

Solution:

There are three available alternatives to correct governor instability. The three alternatives are listed bellow. All three alternatives may or may not be required to correct the governor instability or surging problem on your excavator.

1. Adjust the idle subspring as per the Governor Adjustment section in SENR5546, "3064 and 3066 Engines for Caterpillar Built Machines, Systems Operation, Testing and Adjusting". (See ATTACHMENT.)

2. Replace the idle subspring assembly with a 155-7170 Idle Subspirng Assembly. See Item 4 in the illustration in the ATTACHMENT.

3. Maximize the governor droop. See SENR6572, "Supplement for ZEXEL Fuel System".

ATTACHMENT

Governor Adjustments

Points of Adjustment

(1) Set screw of governor

(2) Control lever

(3) Low idle set screw

(4) Idle subspring

(5) Bolt for stopping at full load

(6) Stop lever

If the engine rpm tends to fluctuate, turn the idle subspring (4) clockwise. Allow the idle subspring to come into slight contact with the tension lever. The engine rpm will rise slightly and the engine rpm will stop fluctuating when the idle subspring is exerting some force upon the tension lever.

NOTE: Tightening the idle subspring adjusting screw is likely to cause the engine to overspeed when the load is dumped during heavy-duty operation. Tighten the idle subspring slowly until the unstable condition is eliminated.

COPYRIGHT 1999 CATERPILLAR ALL RIGHTS RESERVED

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