D80A-12型推土机的NH-220型柴油机配有PT燃油系统。一般在大修或经长期使用后发动机马力不足和冒黑烟时,要对PT燃油系统喷油正时进行调整。喷油正时是用垫片改变随动臂对凸轮的位置,从而改变喷油提前角来调整。喷油提前角一经调整后,发动机工作时是基本不变的。说明书及杂志上发表过关于喷油正时的调 The NH-220 diesel engine of the D80A-12 bulldozer is equipped with a PT fuel system. Generally, the timing of fuel injection of the PT fuel system is adjusted when there is insufficient engine horsepower and black smoke after overhaul or long-term use. The timing of the injection is to change the position of the follower arm to the cam with a shim so as to adjust the injection advance angle. Once the injection advance angle is adjusted, the engine is basically unchanged during operation. The manual and magazine published the timing of fuel injection timing