FREE CDL Doubles/Triples Practice Test 2026
The Doubles/Triples (T) endorsement is required to pull two or three trailers. It covers coupling and uncoupling multiple trailers, inspecting them, and the unique handling and rollover risks of these long combinations.
What is a converter dolly?
About the CDL Doubles/Triples Test
Adding a second or third trailer multiplies both capacity and risk, and the Doubles/Triples endorsement test reflects it. The biggest hazard is the 'crack-the-whip' effect, where a small steering input at the tractor becomes a violent swing at the rear trailer - the leading cause of rollovers in these combinations. The exam covers coupling and uncoupling multiple trailers and converter dollies in the correct order, inspecting every connection and air line, and keeping speeds low and steering smooth to prevent that rearward amplification.