Air Splitter Valve for Eaton Fuller RTLO-18718 18-Speed

This is the air splitter valve that controls the auxiliary section on an Eaton Fuller RTLO road-ranger box. It is World American part number K3331, supplied as a complete kit with the valve body, the O-rings that seal it to the auxiliary housing, and the elbow fitting. It fits RTLO14718, RTLO16718 and RTLO18718, plus the RTLOF14718B, RTLOF16718B and RTLOF18718B overdrive variants.

The splitter valve is what turns the thumb switch on your shift knob into an actual gear change. Air from the regulator runs through this valve to the splitter cylinder on the aux section. When the valve wears internally or the O-rings go hard, the splitter gets lazy or quits: the high split takes a couple of seconds to catch, it falls back into low split under load on a grade, or you hear air hissing at the aux housing with the truck sitting. Drivers usually blame the shift knob or the air lines first, but on a high-mileage RTLO the valve itself is the common culprit once you have ruled out a cracked line and a bad knob.

It is an on-truck repair - the aux section does not have to come apart. Drain the air system so there is no pressure at the valve, mark and pull the air lines, then take out the mounting bolts and lift the old valve off. Clean the mating face on the housing so the new O-rings have a flat surface to seal against, seat the O-rings dry, and set the new valve on without cocking it. Once it is bolted down and the lines are back on their original ports, charge the system and cycle the splitter several times with the engine off, listening at the valve for leaks before you take it out on the road.

This unit crosses to Fuller 4300927, 4304031, 4304032, A-6862, FUL-K3331, K-3329, K-3331 and K3331B, Mack 3088-K-3331, Navistar FULK-3331 and NSFSK3331, Newstar S-10291, Timken M13K-3331, and Freightliner FUL K3331. Check the number on the valve you are pulling off against that list before you order.