气刹测试

解释：过度使用导致高温、调整不当、气压不足，都会引起制动衰退或失效；未充分利用发动机制动也会恶化问题。 / EXPLANATION: Brakes can fade or fail from excessive heat caused by using them too much and not relying on the engine braking effect, they are also affected by adjustment, and low air pressure.

解释：空气制动实际上包含三套系统：行车制动、驻车制动与紧急制动；无线电通信系统不属于空气制动系统。 / EXPLANATION: Air brakes are really three different braking systems: service brake, parking brake, and emergency brake.

解释：牵引车保护阀可在挂车脱离或发生严重泄漏时**保持牵引车**制动系统内的空气；当气压过低（通常 **20–45 psi**）时会自动关闭。 / EXPLANATION: The tractor protection valve keeps air in the tractor or truck brake system should the trailer break away or develop a bad leak, and it will close automatically if air pressure is low (typically 20-45 psi).

解释：紧急制动系统会使用行车制动与驻车制动系统的部分部件，在常规系统失效时使车辆停车。 / EXPLANATION: The emergency brake system uses parts of the service and parking brake systems to stop the vehicle in a brake system failure.

解释：制动刚下长坡非常烫时，或在冰冻天气制动非常湿时，不要使用驻车制动；否则可能损坏或冻住。改用轮挡。 / EXPLANATION: Don’t use the parking brakes if the brakes are very hot (from just having come down a steep grade), or if the brakes are very wet in freezing temperatures. If they are used while they are very hot, they can be damaged by the heat. If they are used in freezing temperatures when the brakes are very wet, they can freeze so the vehicle cannot move. Use wheel chocks instead.

解释：寒冷天气每天检查酒精容器并按需补充。 / EXPLANATION: Check the alcohol container and fill up as necessary, every day during cold weather.

解释：**当弹簧制动已介入时，切勿**踩下制动踏板；弹簧力与气压的合力可能损坏制动器。 / EXPLANATION: Never push the brake pedal down when the spring brakes are on. If you do, the brakes could be damaged by the combined forces of the springs and the air pressure.

解释：压缩空气通常含有水和少量压缩机油，对空气制动系统不利。水在低温下会结冰导致制动失效；水和油易沉积在储气筒底部，应彻底放净。 / EXPLANATION: Compressed air usually has some water and some compressor oil in it, which is bad for the air brake system, the water can freeze in cold weather and cause brake failure. The water and oil tend to collect in the bottom of the air tank. Be sure that you drain the air tanks completely.

解释：调压阀（governor）控制压缩机的启停；当储气筒压力达到约 125 psi 的“切断”值时停止充气；当压力降至约 100 psi 的“接通”值时再次启动充气。 / EXPLANATION: The governor controls when the air compressor will pump air into the air storage tanks. When air tank pressure rises to the “cut-out” level around 125 psi, the governor stops the compressor from pumping air. When the tank pressure falls to the “cut-in” pressure around 100 psi, the governor allows the compressor to start pumping again.

解释：交通部要求：**1998 年 3 月 1 日及以后**生产的空气制动车辆必须配备 ABS。 / EXPLANATION: The Department of Transportation requires that ABS be on: air brake vehicles built on or after March 1, 1998.

解释：踩踏越重，施加到制动器的气压越大；松开踏板则减压并释放制动。 / EXPLANATION: You put on the brakes by pushing down the brake pedal. Pushing the pedal down harder applies more air pressure. Letting up on the brake pedal reduces the air pressure and releases the brakes.

解释：空气制动使用压缩空气来工作。它是让大型、重型车辆安全停车的良好方式，但必须得到良好维护并被正确使用。 / EXPLANATION: Air brakes use compressed air to make the brakes work. Air brakes are a good and safe way of stopping large and heavy vehicles, but the brakes must be well maintained and used properly.

解释：长/陡下坡时脚刹只是发动机制动的**补充**。预先选好低挡位，只需轻踩到**明显减速**即可。 / EXPLANATION: The use of brakes on a long and/or steep downgrade is only a supplement to the braking effect of the engine. Once the vehicle is in the proper low gear you should only have to apply the brakes just hard enough to feel a definite slowdown.

解释：警报灯和蜂鸣应在任一系统低于 60 psi 前亮起/响起。行驶中发生这种情况，应立即停车并安全靠边。若一套系统压力很低，前轴或后轴的常用制动将不能完全工作，停车距离会变长；修复后再继续行驶。 / EXPLANATION: The warning light and buzzer should come on before the air pressure drops below 60 psi in either system. If this happens while driving, you should stop right away and safely park the vehicle. If one air system is very low on pressure, either the front or the rear brakes will not be operating fully. This means it will take you longer to stop. Bring the vehicle to a safe stop and have the air brakes system fixed.

解释：若气压建立过慢，行驶中可能降至过低而不得不紧急停车。在修好之前不要上路。 / EXPLANATION: If air pressure does not build up fast enough, your pressure may drop too low during driving, requiring an emergency stop. Don’t drive until you get the problem fixed.

解释：在气压充满后，熄火、释放驻车制动并计时气压下降。单一车辆在释放行车制动时，每分钟泄漏应小于 2 psi；在踩住制动时，每分钟泄漏应小于 3 psi。 / Right! EXPLANATION: With a fully-charged air system, turn off the engine, release the parking brake, and time the air pressure drop. The loss rate should be less than two psi in one minute for single vehicle brakes released, and three with the brakes applied.

解释：为维持相同速度而不得不加大踩踏力，说明制动正在衰退。 / EXPLANATION: Increasing application pressure to hold the same speed means the brakes are fading.

解释：无论是牵引车-挂车还是单一车辆，测试弹簧制动自动介入的方法与测试低气压报警类似：反复踩放制动踏板，这次要降到更低的气压，直到驻车制动阀关闭或弹出。 /  EXPLANATION: On both tractor-trailers and single vehicles, to test whether the spring brakes will come on automatically, use the same method you use for testing the low air pressure warning signal: Step on and off the brake pedal, this time until you reach an even lower psi reading and the parking brake valve closes or pops out.

解释：当你踩下空气制动，系统通过一个由气压驱动的**电开关**点亮刹车灯，以警示后方车辆。 / Right! EXPLANATION: Drivers behind you must be warned when you put your brakes on. The air brake system does this with an electric switch that works by air pressure. The switch turns on the brake lights when you put on the air brakes.

解释：在气压充满后，熄火、释放驻车制动并计时气压下降。单一车辆在释放行车制动时，每分钟泄漏应小于 2 psi；在踩住制动时，每分钟泄漏应小于 3 psi。 /  EXPLANATION: With a fully-charged air system, turn off the engine, release the parking brake, and time the air pressure drop. The loss rate should be less than two psi in one minute for single vehicle brakes released, and three with the brakes applied.