CDL Doubles Triples — Đề Thi Thử Tiếng Việt 2026
Free CDL Doubles/Triples (T endorsement) practice — required to pull two or three trailers. Real test is in English; native-language explanations + English-term glossary. ~20 questions on the real test, 80% to pass.
📋 Cần Mang Theo
- ✓
Existing CDL or Commercial Learner's Permit
The T endorsement is added on top of a CDL.
- ✓
Proof of identity & required documents
Bring the documents your state DMV lists for adding an endorsement.
📅 Cách Đặt Lịch
- 1
Study Section 7 (Doubles and Triples)
Cover pulling doubles/triples (crack-the-whip rollover, space management, dolly ABS), coupling and uncoupling, inspecting (the shut-off valve positions), and the air-brake checks. The manual also points to Sections 2, 5, and 6.
- 2
Pass the Doubles/Triples knowledge test (in English) at your DMV
About 20 questions, 80% to pass. This endorsement is knowledge-test only. Fees and scheduling vary by state.
💡 Mẹo Ngày Thi
- •Learn the key English terms even if you study in Chinese/Spanish: crack-the-whip effect, converter dolly, pintle hook, fifth wheel, shut-off (glad hand) valve, tractor protection valve.
- •Master the high-stakes safety facts: doubles/triples roll over more easily (the LAST trailer is most likely) so slow down for curves; converter dollies built on/after March 1, 1998 must have ABS (yellow lamp on the left); and NEVER unlock the pintle hook while the dolly is still under the rear trailer — the tow bar may fly up.
- •Know the shut-off (glad hand) valve positions: at the rear of the FRONT trailers they must be OPEN; at the rear of the LAST trailer CLOSED; and the converter dolly air tank drain valve CLOSED. You must have air all the way to the back.
📚 Sổ Tay Học Tập
Tất cả câu hỏi đều dựa trên các phần dưới đây. Nhấp để đọc nguồn chính thức.
🎯 Luyện Tập Theo Chủ Đề
Pulling Doubles and Triples
Why doubles and triples need special care: they are less stable and more likely to roll over because of the crack-the-whip effect (the last trailer whips hardest), so steer gently and slow down for curves; allow more following distance and space; and converter dollies built on/after March 1, 1998 must have antilock brakes (a yellow lamp on the left).
Coupling and Uncoupling
Coupling and uncoupling doubles/triples correctly — basic to safe operation, and dangerous if done wrong: securing the second trailer, handling the converter dolly, the coupling and uncoupling sequences, coupling triples, and the key caution — never unlock the pintle hook while the dolly is still under the rear trailer (the tow bar may fly up).
Inspecting Doubles and Triples
The extra inspection items on doubles/triples (beyond the Section 2 seven-step inspection): the fifth wheels (lower and upper), air and electric lines, the sliding fifth wheel, landing gear, and the shut-off valve positions — the valves at the rear of the front trailers must be OPEN and at the rear of the last trailer must be CLOSED, with the converter dolly air tank drain valve CLOSED.
Checking Doubles and Triples Air Brakes
The extra air-brake checks for doubles/triples: the air-flow test (open the emergency line valve at the rear of the last trailer — you should hear air, proving the whole system is charged), testing the tractor protection valve (it should go to emergency, usually 20-45 psi), and testing the trailer emergency and service brakes.
🔗 Tài Nguyên Chính Thức
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❓ Câu hỏi thường gặp
Bài thi CDL Doubles Triples có bao nhiêu câu và cần đúng bao nhiêu để đậu?
Bài thi lý thuyết CDL Doubles Triples có 20 câu. Bạn phải trả lời đúng 16 câu (80%) để đậu.
Bài thi CDL Doubles Triples được sai tối đa bao nhiêu câu?
Bạn được sai tối đa 4 trong 20 câu mà vẫn đậu.
Cần mang gì khi đi thi CDL Doubles Triples?
Existing CDL or Commercial Learner's Permit — The T endorsement is added on top of a CDL. Proof of identity & required documents — Bring the documents your state DMV lists for adding an endorsement.
Làm sao để đăng ký và thi CDL Doubles Triples?
1. Study Section 7 (Doubles and Triples): Cover pulling doubles/triples (crack-the-whip rollover, space management, dolly ABS), coupling and uncoupling, inspecting (the shut-off valve positions), and the air-brake checks. The manual also points to Sections 2, 5, and 6. 2. Pass the Doubles/Triples knowledge test (in English) at your DMV: About 20 questions, 80% to pass. This endorsement is knowledge-test only. Fees and scheduling vary by state.