Inspecting Doubles and Triples
What the inspection adds
Doubles and triples need everything a single trailer needs, plus an inspection of every coupling point and every converter dolly. Walk the whole combination in one direction so no joint is skipped.
- Tractor fifth wheel: jaws closed around the kingpin, release handle in, safety latch engaged, plate greased, mounting bolts tight, no gap at the apron.
- Converter dolly: frame and drawbar free of cracks or bends; fifth wheel jaws and latch; pintle eye not worn thin; safety chains crossed and attached; landing legs fully raised and pinned; tires, rims, and lugs; mud flap.
- Pintle hook: latch closed, safety pin or cotter in place.
- Air and electrical: each line free of cuts, bulges, and chafe; a gasket in every glad hand; lines supported and not rubbing; shut-off valves in the correct position - open toward a trailer, closed on unused couplers; electrical cord locked into its receptacle.
- Brakes: slack adjusters and pushrods, chambers, and hoses on each trailer; verify that each trailer's brakes apply and release with the trailer hand valve.
- Lights and ABS: use a helper or a wall to check stop, turn, and tail lamps on the last trailer, and confirm the ABS lamp on each trailer does its self-check.
Traps
A stem may describe checking only the rear trailer's lights and skip the dolly, or claim the dolly needs no inspection because it is not a trailer. Another asks which connection the safety chains belong to - the answer is the pintle hook, not the fifth wheel.
Rule of thumb
Inspect each joint as if it were the only one: jaws, coupler, chains, lines, valves.