d. protein. All other trailer air functions use the emergency line. 12, 3. Page 7-6 Commercial Driver's Manual/2.0 = Be sure air lines are supported and glad hands are properly connected. When only pulling one trailer, be sure the shut-off valves are all in the fully closed position. All ABS equipped units Then, the air loss from the leak will lower the air tank pressure quickly. There are more things that can go wrong, and doubles/triples are less stable than other commercial vehicles. Safety fail-safe features of a tractor-trailer converter dolly. Doubles and triples are more likely to overturn than other combination vehicles because of the whip cracking effect. Before you can supply air to the air tanks of a second trailer you need to: Open the shut-off valves at the rear of the first trailer and close the shut-off valves at the rear of second trailer. B A. make things look smaller and farther away than they really are Doubles and triples are more likely to turn over than other combination vehicles because of the "crack- the-whip" effect. The couplers have a rubber seal that prevents air from escaping. Any combination of vehicles with a gross combined weight rating (GCWR) of 26,001 or more pounds, providing the gross vehicle weight rating (GVWR) of the vehicle being towed is in excess of 10,000 pounds. How many different ways of coupling and uncoupling trailer combinations are there? 1/4 in. The crack the whip effect that troubles trucks with trailers. Pull gently against the pin of the second trailer. When driving a double or triple trailer, greater care must be given to. When uncoupling doubles or triples, what is important to know about unlocking the pintle hook? With the red knob pushed in on the tractor dash, the service line should have air in it. Ship to Store. The road is dry and the visibility is good. C. slow to a safe speed before entering the curve, then coast through it, Which of these is NOT a good thing to do when driving on slippery roads? speed and start spinning again, in turn stopping your skid, All the listed answers would be correct. mTouch Quiz will automatically populate the fields below. For emergency braking you should: You are doing a walk around inspection of a double or triple trailer rig. B. do not need to be checked as often as flat mirrors because they show a larger area Hit the article to see the way to back up your trailer like a pro! What is the most common foundation brake found on heavy vehicles? You should keep at least ___ seconds of space ahead of you. When you do this, you should hear: They provide the air pressure used to operate trailer brakes. your vehicle is so long that you must swing wide to make a turn. There is no requirement or exact standard for color coding. You will not be tested on uncoupling twins unless you want to get a double/triple trailer endorsement on your license. You are driving with double trailers and must use your brakes to avoid a crash. The tanks will hold enough air to allow the brakes to be used several times even if the compressor stops working. How do you know if your converter dolly is equipped with antilock brakes? At section 2 downstream, the speed is 519 m/s. Watch the wording of the question AND the answers A safe driver will look for all of the above. B. closed kingpin. when does the drivers manual say you should disable the steering axle brakes? Which of these statements about the handling of doubles and triples is true? Which diagram shows the best way to turn? They are not only longer, but also need more space because they cannot be turned or stopped suddenly. Converter dollies are connected to front trailers with a? 0000001775 00000 n Park on level ground, put chock on the tires, and charge the air tank. If you are driving a 200-foot triple at 35 mph, what is the minimum amount of space (in seconds) that you should keep ahead of you? Slow to a safe speed before entering the curve, then coast through the curve. C. always keep your vehicle to the left side of your lane, When testing the coupling of double trailers, the landing gear of the rear trailer should be: 1. Study section 6.2 if you can't answer all of these questions. open the shut-off valves at the rear of the first trailer and close the shut-off valves at the rear of the second trailer, enclose converter dolly air tank drain valves B You should keep at least ____ seconds of space ahead of you. Locking jaws closed on 0000003240 00000 n You should check the height of the trailer before connecting a converter dolly to a second or third trailer. Safety chains secured to trailer (s). If there is air there, then there is air towards the cab You want to hook up to the first trailer, then the converter dolly while it is lined up in Take special care when pulling two and three trailers. 4. behind the shut-off valve then they need to remain open. To do this without wheels chocks you should: Supply air to the trailer air system with the tractor and then disconnect the emergency line. For emergency braking you should: the crack-whip effect that triubkes trucks with trailers is most likely to cause a tip over when. Wait for air pressure to reach normal, then push in the red trailer air supply knob. Sketch the shape of the passage between sections 1 and 2. You should keep at least ____ seconds of space ahead of you. To uncouple the rear trailer in a set of doubles, the shut-off valve at the rear of the front trailer should be: Closed. Remember, the service line is not used unless you depress the brake pedal or use the trailer hand valve. 0000005345 00000 n C You may be timed. When you do this, you should hear: 0000006383 00000 n The Verge logo. We've all wondered if the adventure and challenges of life on the open road would suit us better than the ordinary day to day lives we've always known. Any items you have not completed will be marked incorrect. You are visually checking the coupling of a converter dolly to the rear trailer. B You should avoid traveling next to others when possible. good speed management says you should, may have poor traction due to bouncing and wheel lock up. Take this same test in our other testing modes How to Get a Hazardous Materials Endorsement, What is a CDL? You should NOT: You are driving a set of doubles and a set of trailer wheels goes into a skid. What should you check for when inspecting the converter dolly? For emergency braking you should: which of these statements about emergency steering is true? This would be very dangerous. A) closed . Which of the following is true about loading cargo into double or triple trailers? paramount to safe driving. The rear trailer does not have shut-off valves. Remember: The trailer air brakes are supplied with air using the emergency line (also called the supply line). What is a converter dolly? When testing trailer service brakes, you should use? What types of trailers can get stuck on raised crossings? You are doing a walk around inspection of a double or triple trailer rig. Open the emergency line shut-off valve at the rear of the last trailer. Have little braking power because they are small What do you check when making a visual check of coupling? B The DMV doubles triples practice test will examine your knowledge of pulling double/triple trailers, coupling and uncoupling, inspecting doubles and triples, and checking air brakes. If the dolly is a two axle unit then 1 The service air line is only used to control the service brakes (when you press on the brake pedal or use the trailer hand-valve). 10 In double and triple trailers, the trailer air supply control should pop or _________ when air pressure drops into the range of 20 to 45 psi. go to the rear of the second trailer and open the emergency line shut off, before you can supply air to the air tanks of the second trailer you need too, open the shut-off valves at the rear of the first trailer & close the shut-off valves at the rear of the second trailer. Opening the shut off valves on the rear most trailer will ensure the lines are flowing 0000006015 00000 n The dolly tow bar may flip up causing bodily injury and making it very difficult to To check air flows to all trailers, you should let air pressure reach normal then? D You should be sure the converter dolly air tank drain . These mirrors: Therefore, look far ahead so you can slow down or change lanes gradually when necessary. the trailer will be raised slightly when the converter dolly is backed under it the best way to keep brakes from getting too hot while going down long grades is to : go slow and use only light, steady pressure on the brakes you are driving a 100ft truck with double trailers at 30mph. Tips for Backing Up a Trailer Like a Pro Trucker. You want to lock your combination to a second trailer that has no spring brakes. Why should you pull a dolly out from under a trailer before you disconnect it from the trailer in front? The shortest trailer Some areas of concern are discussed below. should remain in the closed position. 2 Light cords firmly in sockets on trailer. When inspecting doubles and triples you must make sure there is air all the way to the back of the last trailer, otherwise what may not work? you should keep atleast __seconds of space ahead of you. They provide the air pressure used to operate trailer brakes. With the hand valve on, you should test the trailer brakes by opening the service line valve at the rear of the rig. Any vehicle required by federal regulations to be placarded while transporting hazardous materials. The driver will be required to complete this requirement in three eight hour shifts. If there is a trailer When turning a double or triple at an intersection, the turn often cannot be completed without swinging wide. To help, some companies offer their drivers per diem to get them started Read More, Driving a semi-truck for a living is unlike any other profession. On double and triple combinations, you must make sure that which of these is secure? Connect the Converter Dolly to the Rear Trailer: Test the coupling by pulling against the pin of the second semitrailer. There are more things that can go wrong, and doubles/triples are less stable than other commercial vehicles. 60607. B. you need about four times as much stopping distance at 40 mph as at 20 mph 6. The heaviest trailer 0000008915 00000 n you should not, when you turn with the tractor/triple trailer combination the wheels that offtrack(cheat) the most are. Follow the procedures described later in this section. The dolly tow bar may fly up, possibly causing injury, and making it very difficult to When checking the coupling system, make sure that the locking jaws are around the shank of the. True False True If you want to couple a second trailer to you combiantion vehicle, secure it by using the: Trailer emergency air brakes. A. the total stopping distance of a truck is the distance it takes to stop once the brakes are put on at any speed CDL Doubles and Triples Test Question and Answers 2023 [PDF]: Commercial Drivers License Doubles and Triples Endorsements Knowledge Test. 2. A converter gear or dolly is a coupling device of one or two axles and a fifth wheel by which a semi-trailer can be coupled to the rear of a tractor-trailer combination forming a double bottom. A. require shorter stopping distances than full ones You need to brake in order to regain control. Shut-off valves (also called cut-out cocks) are used in the service and supply air lines at the back of trailers used to tow other trailers. You can find it here: High Road 2.0. Air will not be available to release the trailer spring brakes (parking brakes). Hook dolly to front trailer. If this lamp is illuminated and does not go out, C. foot pedal, Which of these statements about managing space to the sides is true? True! What does the drivers manual say about how much space you should keep ahead of your truck? C. open, except the one connected to the rear trailer should be closed, During normal operation the brakes on double and triple trailers are controlled by the: It is extremely unlikely you will drive a trailer built before 1975, but for the written exam, you still may need to know that trailers built before 1975 were not required to have spring brakes. This has the same value as the %%PERCENTAGE%% Variable on the Final Screen. You must check that all shut-off valves are in the open position except the ones at the back of the last trailer, which must be closed. Go to the rear of the rig. Nothing, the weight of the trailer will keep it in place, 10. Tractor-trailers are considered combination vehicles. A. release the spring brakes and check for movement when testing the coupling of a double trailer the landing gears of the rear trailer should be, you must drive through deep or flowing water . Hb```f``b`c``e@ (Q6_* Explore now! If you do, the brakes may not work correctly. All of the above, 6. B 0000003261 00000 n The rear trailer of a double There is no obligation whatsoever. You must treat a flashing red signal as you would treat a STOP sign.