Towing Multiple Trailers and Converter Dollies
The dolly is the weak link
The converter dolly is a short, two-wheeled unit that converts a single-trailer tractor into a multi-trailer rig. Its upper coupler holds the rear trailer's kingpin; its drawbar or pintle hook attaches to the lead trailer. Because it is short and light, it is the component most likely to fail or to be misconnected, and questions focus on it.
Concepts to name
- Pintle hook and ring: the connection between the dolly and the lead trailer; the safety chains must be crossed and attached.
- Upper coupler: the plate and kingpin receiver on the dolly that holds the rear trailer.
- Air and electrical connections: the dolly carries lines from the lead trailer to the rear trailer; all must be secure and leak-free.
- Dolly wheels and tires: small tires turn fast and wear quickly; check them at every stop.
- Dolly brakes: many dollies have their own brakes; confirm they are functioning.
Common traps
A common trick is to imply the dolly can be towed without safety chains if the pintle hook is locked - chains are still required. Another is to suggest the dolly's air lines can be left disconnected if the rear trailer has its own supply - they cannot. Questions also test whether you know the dolly must be inspected as its own unit.
Rule of thumb
Treat the dolly like a separate trailer: hook it up, check the pintle and chains, connect the lines, and inspect the tires and brakes before every trip.