Doubles and Triples
Everything you need to pass the CDL Doubles/Triples (T) endorsement test: a study guide based on the official CDL manual, a quick review of the key facts, 49 practice questions with answers, and narrated audio you can listen to anywhere. Instant access for 120 days.
Overview
Doubles/Triples covers multiple-trailer operation, including coupling, inspections, stability, and following distance.
When Is This Useful?
Can help drivers qualify for line-haul, LTL, parcel, and regional freight roles that use multiple trailers.
Who Is This For?
Class A drivers who plan to pull double or triple trailer combinations where allowed.
Topics Covered
Converter dollies connect multiple trailers in double and triple combinations and must be coupled correctly including pintle hooks and safety chains. An improperly connected dolly is a primary cause of trailer separation.
Doubles and triples require multiple coupling points, each with its own procedure and inspection checklist. A missed connection at any point can result in a runaway trailer at highway speed.
Multiple-trailer combinations are more prone to rearward amplification and rollover than standard tractor-trailers, especially on curves. The exam tests why these forces occur and how to manage vehicle stability.
Inspecting a double or triple combination requires covering more connection points and a longer inspection sequence than a standard rig. You will learn the full inspection order for multi-trailer combinations.
The added length and weight of double and triple combinations increases stopping distance significantly beyond a standard combination vehicle. Exam questions cover safe following distances at various speeds and road conditions.
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Get Doubles and Triples plus more, for less than buying separately.