UNIVERSAL JOINT GP 4447833 - Caterpillar

Illustration 1 g01315383
(1) Body (A) Dimension 3.81 mm (0.150 inch)
Illustration 2 g01317080
(2) Compensator spool (B) Dimension 0.79 mm (0.031 inch)The body (1) was manufactured with a smaller metering notch on certain control valves. The smaller notch does not allow the pressure that is compressing the spring to be vented to the tank. The slot of the compensator spool must be open to the tank when the control spool is in neutral or the pressure is transmitted to the end of the compensator spool (2) through the passage in the center of spool. As this pressure increases to system pressure, force increases on the spring. The force on the compensator spool will cause the spring to move to a solid length. The spring may fracture after sufficient cycles over an extended period.The compensator spool (2) cannot vent the blocked pressure to the tank if the metering land in the body (1) exceeds dimension (A) .The compensator spool (2) can be machined in order to compensate for the defect in the valve body (1). This process will ensure that the spool will vent the spring cavity to the tank when the control spool is in NEUTRAL. The groove on the compensator spool must be machined by removing material to dimension (B) from the land at the end of the groove. By making the groove wider, this will compensate for the metering notch in the body.The compensator spool (2) ensures a constant pressure drop across the main spool. The removal of this material will not adversely affect the normal performance of the compensator spool (2) .Note: The procedures apply to all control valves that use the 6E-4317 Spring .The 300-5444 Compensator Spool may be used as an alternative repair for the problem regarding the metering notch. The 300-5444 Compensator Spool can be used on machines that have not installed a 278-9570 Compensator Spool . The 278-9570 Compensator Spool must be machined if the spool has already been installed.