Final answer:
A converter dolly is a trailer component used in the trucking industry to connect two or more trailers together. They do have spring brakes as an important safety feature.
Step-by-step explanation:
A converter dolly is a trailer component that connects two or more trailers together to form a longer combination vehicle.
It is commonly used in the trucking industry to improve efficiency by allowing a single truck to haul multiple trailers. The converter dolly typically has a fifth wheel plate or a pintle hook on one end to attach to the rear of the lead trailer, and a kingpin or ball hitch on the other end to attach to the front of the following trailer.
Spring brakes are an important safety feature in trailers, including converter dollies. The purpose of spring brakes is to provide an additional braking force in case the air brake system fails. They are typically activated by a mechanical spring when air pressure is lost, helping to prevent a runaway trailer.