LUBRICANT-A/C 4C2960 - Caterpillar

Introduction
The problem that is identified below does have a known permanent solution. Use the solution that is identified below.Problem
There have been reports that the pressure reducing valve cartridge and sequence valve cartridge in the brake accumulator charging valve group may generate noise on certain 988K Large Wheel Loaders.Solution
The 335-1074 pressure reducing valve provides improved stability and reduced noise over the entire operating pressure and flow range. Replacing the 423-1880 sequence valve with the 263-3891 cavity plug eliminates noise caused by the sequence valve.
Table 1
Parts List    
Qty     Part Number     Description    
1     263-3891     Cavity Plug    
1     335-1074     Pressure Reducing Valve    
Illustration 1 g03853272
View of brake accumulator charging valve group location (A) brake accumulator charging valve group
Illustration 2 g03853287
View of the brake accumulator charging valve without the sequence valve cartridge (1) 369-8183 Pressure Reducing Valve Cartridge Remove pressure reducing valve (1) and install 335-1074 Pressure Reducing Valve . Adjust 335-1074 Pressure Reducing Valve to pilot supply pressure of 3800 200 kPa (550 30 psi).
Illustration 3 g03853285
View of the brake accumulator charging valve with the sequence valve cartridge (2) 423-1880 Sequence Valve Gp Note: On S/N:TWX1-387 and ; S/N:LWX1-520 only: Remove sequence valve cartridge (2) and install the 263-3891 Plug-Cavity .