When uncoupling a doubles combination, in what order should the trailers be disconnected?

UNCOUPLING DOUBLES requires a specific sequence to prevent equipment damage and safety hazards from uncontrolled dolly movement. CORRECT SEQUENCE FOR UNCOUPLING A DOUBLES: STEP 1 — Park the combination; set the tractor parking brakes; charge the trailer air supply to set all trailer emergency brakes; STEP 2 — Uncouple the REAR TRAILER from the converter dolly: support the rear trailer's weight by cranking down its landing gear; disconnect the pintle hook; remove safety chains; disconnect air and electrical lines from the rear trailer; STEP 3 — Move the tractor with the first trailer and now-empty dolly to a separate location; STEP 4 — Park the tractor and front trailer; set the dolly's parking brake if equipped; lower the dolly's landing legs; disconnect the dolly from the first trailer's pintle ring and remove it; STEP 5 — Uncouple the tractor from the first semitrailer using standard uncoupling procedure. WHY THE ORDER MATTERS: If the dolly is disconnected from the front trailer before the rear trailer is removed from the dolly, the dolly and rear trailer are left as a freestanding unit with no tractor control — the dolly's air brakes will hold them temporarily, but this is an unstable configuration that must be managed carefully.