Idle speed of concrete mixer is not a speed, but a working condition. When the engine idles, it is called idle, that is, the mixer gear is neutral. The speed at which the engine is idling is called idle speed. Idle speed can be adjusted by adjusting the size of the damper. Idle speed means that the engine is not working. Idling the engine costs a lot of oil. Experiments show that the engine idling for 1 minute is about the same as the fuel consumption of driving about 6 km. When the idle speed value of the mixer engine is lower or higher than the specified range, the phenomenon of unstable stage and speed will appear. How to judge whether there are idle problems in the engine of concrete mixer, and how to solve them?

1、混凝土搅拌车发动机怠速不稳怎么办?

1. Concrete mixer engine idle instability how to do?

怠速不稳表现为：怠速运转时，发动机发抖、转速不均匀。其产生的原因有：怠速空气量孔堵塞，怠速装置工作不良，个别缸火花过弱，个别气门密封不严，进气歧管漏气，点火时间过早或过迟，怠速调整不当等。

Idle instability performance: idle running, engine shaking, uneven speed. The causes are as follows: the idle air orifice is blocked, the idle device is not working well, the spark of individual cylinder is too weak, the seal of individual valve is not tight, the intake manifold leaks, the ignition time is too early or too late, and the idle speed is not adjusted properly.

发动机怠速不稳时，应调整怠速，如怠速调整后故障仍不能，则应检查怠速量孔与怠速空气量孔是否堵塞，如量孔堵塞，可用汽油或丙酮清洗并用压缩空气吹通；如量孔未堵塞，应将发动机转速稳定在一定的转速下，察听进气歧管或化油器中、下部衬垫处是否漏气，如出现漏气现象，可用紧固螺钉或加、减垫片的方法来排除。

When the idle speed of the engine is unstable, first adjust the idle speed. If the fault can not be eliminated after the idle speed adjustment, check whether the idle speed measuring hole and idle air measuring hole are blocked. If the measuring hole is blocked, clean it with gasoline or acetone and blow it through with compressed air. If the measuring hole is not blocked, stabilize the engine speed at a certain speed, and listen to the middle and lower pads of the intake manifold or carburetor If there is air leakage, it can be eliminated by fastening screw or adding or reducing gasket.

如怠速不稳的同时伴有发动机功率下降现象，则应进一步检查火花塞工作情况、气门的密封性能及点火时间是否正确，必要时应进行检修、调整。

If the idle speed is not stable and the engine power drops, further check the working condition of spark plug, the sealing performance of valve and whether the ignition time is correct, and repair and adjust if necessary.

2、怎样判别混凝土搅拌车发动机怠速不良?

2. How to judge the poor idle speed of concrete mixer engine?

工作正常的发动机，应能在300-500r/min的转速范围内均匀运转。如果发动机低稳定转速超过这个转速范围，或在此转速范围内发动机出现熄火、转速不稳，即为无怠速或怠速不良。怠速不良时，可根据其故障特点将其分为怠速熄火、怠速不稳和怠速过高。

The normal engine should be able to run evenly in the speed range of 300-500r / min. If the low stable speed of the engine exceeds this speed range, or if the engine stalls and the speed is unstable within this speed range, it is no idle or poor idle. When the idle speed is not good, it can be divided into idle flameout, unstable idle and too high idle according to its fault characteristics.

如发动机起动后，从低速到高速时运转良好，但一松开加速踏板后就立即熄火，或是先运转不稳继而熄火，则为怠速熄火故障。如发动机怠速运转不平稳，排气管发出“突、突”响声，则一般为怠速不稳故障。如发动机低稳定转速高于规定范围，且又无法使此转速降低，则为怠速过高或无怠速故障。

If the engine runs well from low speed to high speed after starting, but the engine stalls as soon as the accelerator pedal is released, or the engine stalls after unstable operation, it is an idle stalling fault. If the engine idles unsteadily and the exhaust pipe makes a "sudden, sudden" sound, it is generally an unstable idling fault. If the idle speed is too low or too high, the idle speed cannot be reduced.

3、怎样调整混凝土搅拌车发动机怠速?

3. How to adjust the idle speed of concrete mixer engine?

调整怠速工作，必须在发动机温度正常、气门间隙适当、点火系统情况正常、各管道密封良好、阻风门全开、能够关闭严密等正常状况下进行。

The idle speed adjustment must be carried out under normal conditions, such as normal engine temperature, proper valve clearance, normal ignition system, good sealing of all pipelines, full opening and tight closing of choke.

调整时，旋出节气门开度调整螺钉，使发动机达到低稳定转速。接着用螺丝刀旋入怠速调整螺钉，当发动机快要熄火时，再缓慢旋出怠速调整螺钉，使发动机稳定运转并达到高速。然后再将节气门开度调整螺钉旋出，使发动机的转速尽可能降到低。然后再调整怠速调整螺钉，使发动机转速提高。

When adjusting, first screw out the adjusting screw of throttle opening to make the engine reach low and stable speed. Then screw in the idle adjustment screw with a screwdriver. When the engine is about to shut down, slowly screw out the idle adjustment screw to make the engine run stably and reach high speed. Then screw out the throttle opening adjustment screw to reduce the engine speed as low as possible. Then adjust the idle adjustment screw to increase the engine speed.

如此反复进行，直到节气门开度小(接近关闭)，发动机在低稳定转速下运转。然后再提高转速并突然关闭节气门，以发动机不熄火仍然转动为宜。

This is repeated until the throttle opening is small (close to closed) and the engine runs at a low steady speed. Then increase the speed and close the throttle suddenly, so that the engine is still running.

4、混凝土搅拌车发动机怠速熄火怎么办?

4. How to stop the engine of concrete mixer at idle speed?

发动机怠速熄火时，要先根据实际情况对怠速进行调整(如果明确故障的原因，也可直接进行维修)。

When the engine idles out, the idle speed should be adjusted according to the actual situation (if the cause of the fault is clear, it can also be repaired directly).