DRIVE GP-PUMP 2604450 - Caterpillar

LOADERS
953C (2ZN) TRACK-TYPE LOADERTHIS TIB REPLACES THE JUNE 3, 1998 TRACK-TYPE LOADER TIB, COMPONENT CODE: SMCS 3203; "MACHINE TURNS WITHOUT STEER DEMANDS AND HAS LOW TOP SPEED, EVEN AFTER ELECTRONIC ADJUSTMENTS". DESTROY THE JUNE 3, 1998 TIB. IT WILL NOT APPEAR IN THE SEMI-ANNUAL INDEX.Problem:
Some 953C Track Loaders, with higher hours, may drift one or more directions when travelling at high speed. This may even occur within minutes after initially successful electronic adjustments for track synchronization. These problems are more noticeable when operating at oil temperatures higher or lower than the oil temperature at the time of adjustment.In such cases, at least one worn input actuator bore (in the cast iron cover) for the drive pump servo valve have been found. A worn bore can cause internal leakage of pilot signal oil, causing lower pilot pressure at higher oil temperatures. Internal leakage can be confirmed by checking pilot signal pressure at full speed cold, and then full speed hot. There should be no detectable difference in pilot signal pressure from cold to hot.To qualify for this problem, a machine must display an OPERATIONAL problem of steering to one side without input after initially successfully electronic adjustments have been completed. Only a portion of machine population is affected by this problem.Solution:
Replace 127-7041 Actuator Group. Reset the adjustment for mechanical zero displacement.COPYRIGHT 1999 CATERPILLAR ALL RIGHTS RESERVED