NJ CDL Combination study guide
NJ CDL Combination · Work through your exam, one topic at a time.
The New Jersey Commercial Driver License (CDL) Combination Vehicles endorsement covers the knowledge and skills needed to operate a tractor-trailer or other vehicle with a trailer. This page is an independent study resource for candidates preparing for the combination vehicles portion of the NJ CDL knowledge exam. It is not affiliated with the New Jersey Motor Vehicle Commission (MVC) or any government agency, and it does not reproduce any official test. The material is organized around four domains: combination vehicle inspection and coupling/uncoupling; driving combination vehicles safely, including turns, braking, speed, and space management; air brakes and combination vehicle braking systems; and skid control, jackknifing, and hazard response. The NJ CDL Combination study guide has 4 sections and about 1,310 words.
01Combination Vehicle Inspection and Coupling/Uncoupling
A combination pre-trip goes past the single-unit walk-around: fifth wheel jaws and mounting bolts, the apron and kingpin, the gap between tractor frame and trailer, glad hands and their rubber seals, the electrical cord and receptacle, landing gear (legs straight, crank secure, pads present), trailer frame and crossmembers, and the rear underride guard. Shiny metal on the fifth wheel plate is a warning - the trailer is riding on the plate instead of locking into the jaws.
338 words, about 2 min02Driving Combination Vehicles Safely: Turns, Braking, Speed, Space
The rear wheels of a tractor-trailer follow a shorter path than the front wheels, so the trailer cuts the corner. On a right turn the trailer's rear wheels can climb the curb or strike a pedestrian; set up wide enough that they clear, and watch them in the mirrors.
309 words, about 2 min03Air Brakes and Combination Vehicle Braking Systems
The compressor charges the reservoirs; the governor cuts out near 125 psi and cuts in near 100 psi. A safety valve protects the tanks at about 150 psi.
344 words, about 2 min04Skid Control, Jackknifing, and Hazard Response
In a braking skid, release the brake and steer where you want to go. In a drive-wheel (power) skid, ease off the accelerator - spinning drive wheels lose lateral grip and the tractor's rear steps out.
319 words, about 2 min