XB-10087-P
Fifth Wheel Inner Extension Spring, Air Release and Manual Lock
SAF-Holland

Integrated into the fifth-wheel coupling subsystem, this inline extension element provides controlled stiffness to support the air-release function and manual-lock operation. The inner extension spring ensures proper engagement and release sequence, preventing inadvertent coupling or uncoupling during vehicle maneuvers. VMRS 059-001-007 places it within the extension-spring segment that serves critical release mechanisms in heavy-duty towing applications. Category 42809 indicates its use in fifth-wheel control assemblies, where reliable tension supports safe articulation between tractor and trailer. In practice, selecting the correct spring rate and length ensures consistent release force, reduces wear on pins and levers, and helps maintain precise alignment of the kingpin with the trailer coupler. As with all spring components exposed to road conditions, inspect for corrosion, fatigue cracks, and deformation after service cycles, and replace if performance deviates from expected preload. This part contributes to safe, predictable operation of the fifth-wheel system in diverse operating environments.