2006/05/22 Caterpillar

Track-Type Loader:

933C (S/N: 4MS1-UP; 5JS1-UP)

939C (S/N: 6DS1-UP)

Track-Type Tractor:

D3CSeries III (S/N: 4KS1-UP; 4TS1-UP; 5GS1-UP; 5NS1-UP; 7GS1-UP)

D4CSeries III (S/N: 4LS1-UP; 6BS1-UP; 6FS1-UP; 7NS1-UP; 8CS1-UP)

D5CSeries III (S/N: 4WS1-UP; 5HS1-UP; 6CS1-UP; 7PS1-UP; 9AS1-UP)

Description of Change: As the hystat pumps get older, the pumps become more inefficient due to internal leakage that is caused by normal wear. When one of the two pumps is replaced, there may be an imbalance in the system. This imbalance in the system may make the tracking not straight. This imbalance is caused by the newer pump performing more efficiently than the old pump. There is no way to adjust this imbalance out of the system.

Adaptable To: Straight tracking can be restored on the tractor by replacing both of the old pumps with a new Tandem Pump Gp. This pump group includes two new pumps that are bolted together. The tractor will track straight by having two new pumps.