Having problems with your FMTV brakes locking or the parking brake won’t engage or disengage? It’s possible the front service and emergency gladhands have the wrong couplings installed.
While this applies to all FMTVs, TACOM has gotten several inquiries lately from operators of FMTV A1P2 (LTAS) trucks with brake issues.
Each front gladhand must have the vented dummy coupling, NSN 2530-01-477-6586, PN N-30257-A, to allow the excess air pressure to escape from the brake lines.
Vented dummy couplings for front gladhands
You’ll want to make sure that each rear gladhand is equipped with the non-vented dummy coupling, NSN 2530-01-422-2827, PN N-30257.
Another possible reason for locking brakes is a faulty one-way check valve. That’s because corrosion can develop inside the gladhand one-way check valve causing the valve to stay open. This causes air to continue to flow through the gladhand, even after the excess pressure is vented. That’s not supposed to happen, and your FMTV is non-mission capable (NMC) until the gladhand one-way check valve, NSN 4820-01-443-5012, PN 12378846, is replaced.
Help stop corrosion from developing in your air system by doing the AFTER PMCS in the TM and draining the air tanks to remove moisture.
It’s also important to perform a good PMCS on the air dryers following the guidelines in TM 9-2320-333-23&P (Jun 19), IETM 9-2320-391-23&P (Oct 17), TM 9-2320-365-24P (Aug 05) or TM 9-2320-366-24P (Oct 05) based on the FMTV model.