Indiana CDL Doubles & Triples: Air Brakes Test 2026

On a doubles or triples setup, the last trailer's air lines must be closed off, and the Indiana CDL doubles and triples air brake shut-off test makes sure you know which valves to set. This 2026 drill covers the shut-off valves, sometimes called cut-out cocks, at the rear of each trailer and dolly in a multi-trailer combination.

Learn why the shut-off valve on the very last trailer must be closed while the ones feeding trailers ahead must stay open, and how a valve left in the wrong position robs a trailer of its brakes. The Indiana Commercial Driver's Manual explains these valve settings, and because the question count for the doubles and triples exam varies, check your Indiana CDL Manual for the exact number.

This is core knowledge for the T endorsement that lets you pull multiple trailers. Repeat this air brake shut-off drill until the correct valve positions are second nature to you.

Keep going:

• Indiana Doubles and Triples Practice Test
• Indiana Doubles and Triples Practice Test 2
• Indiana Doubles and Triples Endorsement Test
• Indiana CDL Practice Test
• Indiana Air Brakes Practice Test
• Indiana CDL Combination Practice Test
• Indiana CDL Pre-Trip Inspection Practice Test
• Indiana Hazmat Practice Test
• Indiana CDL Practice Test

Every question traces back to the Indiana CDL Manual - skim the right-of-way and signs chapters before your retake.