Reasons and treatment methods of Kobelco excavator falling speed

- Jul 23, 2020-

Phenomenon of speed drop

1. It is normal for the engine speed to fall within 150 rpm

2. The engine speed drop within 200 rpm is a slight drop

3. An engine speed drop of more than 300 rpm is a serious speed drop





The main reason for the speed drop

1. The oil circuit of the fuel system is not unblocked, such as: filter element clogged, air in the oil circuit, solenoid valve failure, etc., will cause speed drop;

2. High temperature of engine coolant and high temperature of hydraulic oil will cause speed drop. Some brands of engine controller will directly reduce the engine speed to protect the engine;

3. Blockage of the engine's intake system will cause the speed to drop;

4. The hydraulic pump power is greater than the engine power, which will lead to the failure: the hydraulic system pressure is too high, the flow is too large, etc.;




Two common situations of speed drop

1.The engine slows down and emits black smoke when working

   Check whether high-quality diesel is used;

   Check whether the air intake system is blocked, the air intake port, air filter element, turbocharger,    air cooler, etc. are blocked or leaked;

   Check whether the flow solenoid valve in the fuel system is stuck at the maximum flow rate (electronic injection engines usually give an alarm);

   Check whether the fuel injector and fuel pump are worn;

   The hydraulic system power is greater than the engine output power: the hydraulic system pressure is too high (check whether the overflow valve is stuck), the flow is too large (the regulating valve is stuck at the maximum flow position), and the oil return is not smooth;

2. The engine slows down during work and no black smoke is emitted

    The air intake of the fuel system and the oil circuit are slightly blocked: the fuel tank, the oil circuit switch (half open), the filter element is blocked, etc., cause the fuel system pressure to be low;