Fault phenomenon: when a Hitachi zx300-5a excavator performs light operations such as horizontal extension of the stick, the coordination between the stick and the boom is not good, and the stick is one beat slower than the boom. During normal excavation operations, no abnormality is felt.
Troubleshooting detection:
Since the inner diameter of this hose is 5/8, which is a special size, and it is often not sold in hose stores on the street, it is often used when using 1/2 inner diameter Under no-load condition, slightly higher working pressure than usual occurs, and the working sound also sounds as if it is blocked.
repair:
1. Due to the damage of the cylinder hose, the customer manufactured and installed it in the street hose store Therefore, the inner diameter of the hose is thinner than the standard (cross-sectional area) Therefore, the return side has a closure, resulting in a decrease in speed.
2. Troubleshooting: replace the hose with a regular product.
Knowledge supplement: failure analysis and maintenance of Hitachi zx300-5a excavator crushing hammer impact energy reduction
Cause analysis:
1. Insufficient oil, low pressure in nitrogen chamber; The pressure of the supply safety valve is low, and the oil temperature is higher than 80 ℃;
2. High return oil back pressure; Pedal deformation control pipeline deformation; The hydraulic pump is damaged and the oil is polluted;
3. Failure of control valve or related parts: the control valve is stuck; The stroke of control valve is insufficient due to loose bolts; There is an internal fault in the cylinder block, and external substances enter.
Maintenance: check the pipeline and dredge the oil circuit so that the back pressure does not exceed the specified value; Inflate to the specified value; Check and repair valves and related parts or replace them: check the cooling system and reduce the oil temperature to the working temperature; Adjust the pressure of the safety valve to the specified value: check the volumetric efficiency of the oil pump, and replace the oil pump if it is low; Check the filter and hose for insufficient oil absorption; Require the supplier to dismantle and repair; Replace the hydraulic pump; Clean or replace.
