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SWMN | there is a whole list of possible issues in the steering system that should be looked at by cat also. If they are not right it wont steer the best no matter what.
Summary
A faulty or worn-out steering valve on the tractor may cause poor performance in the field when
you are using AgGPS® Autopilot. If you continue to use the worn steering valve, you will need to
constantly recalibrate the tractor.
This issue affects the CAT Challenger 35-55 steering valve (PN 40394-10 – Platform Kit CAT
35-55).
Note: AgGPS Autopilot is a high performance system that must be run on equipment equal
to the task. It is the owner’s responsibility to ensure that the tractor is in good condition
before installing Autopilot. If the AgGPS Autopilot system is already installed when you
need to replace the steering valve, it is not the responsibility of Trimble or its
representatives to perform or pay for this servicing.
Problem
If you are using AgGPS Autopilot on a CAT Challenger 35-55 platform (CH55), a worn-out
steering valve could cause poor tractor performance in the field, leading to problems in achieving
consistent repeatability.
The steering valve controls the rate at which the tractor turns (slew rate). When you are using
Autopilot, the slew rate changes according to the position of the servo spool in the piston pump.
When the steering valve is operating correctly, the preset pressure (pump knee) is stable and
Autopilot maintains its calibration. However, if the servo spool sticks, it must be renewed.
Solution
Recondition the piston pump.
Contact your local CAT Dealer for service advice.
Service issues
To ensure correct AgGPS Autopilot performance on Cat Challenger Series vehicles, consider
the update relating to the replacement of the piston pump (new: 198-0914).
Caterpillar SMCS Code: 4306; 5070
AgGPS® Autopilot
June 15, 2009 Agriculture Division
Servo Spool update
This update is not yet required by Cat, but is critical to assure good performance
Replace the old servo spool with a new high-strength, brass servo spool when reworking the
steering pump.
For more information, refer to the Cat Service Bulletin: Media number SEPD0506500
[publication date 2001/0212, Update date 2001/0130].
Other service issues
Steering control valve
When installing the first manifold and valve on CH45 tractors, recondition the steering valve to
correct steering problems.
Note: This issue affects manual steering only, not Autopilot.
Affected product: ID number 8DN 1-990.
Repair before part failure (at desecration of the service facility), or after failure occurs. Date of
Service announcement: June 9, 1999, revised July, 2000.
For more information, refer to the Product Support Program SEBE6921-03.
PS4885 C Replace steering control valve 11/111/99 6/30/02
Hydraulic pump drive
Recondition the pump to improve lubrication flow and prevent the pump from seizing
Affected product: ID numbers 8DN 1-881, SDN897-920, and 8DN935 and higher.
Repaired after failure. Therefore this is not an installation issue.
Date of Service announcement: 3/3/2000
For more information, refer to the Product Support Program SEBE7212-00
PI10077 S Rework hydraulic pump drive 7/26/01. The “S” in this number stands for safety,
meaning that the rework is required for safety reasons. | |
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How much "wiggle" is acceptable with an AutoPilot
