One, repair the following three find out the reason of failure, and to improve the system:

1, check the internal leakage of the boom cylinder:

The simplest method is to move the arm raised, to see whether there is a significant drop in free. If the whereabouts of the obvious disassemble cylinder inspection, such as seals have been found to wear should be replaced.

2, check the control valve:

First clean the safety valve, check valve is worn, such as wear should be replaced. Safety valve if there is no change after installation, check the control valve spool wear, the gap limits is generally 0.06mm, severe wear should be replaced.

3, measuring the pressure of hydraulic pump:

If the pressure is low, then adjust, add stress transfer is still not up, then pump serious wear and tear.

Two, the main reason causing arm load cannot ascend as:

1, pump serious wear. Running at low speed pump leak serious; high-speed operation, the pump pressure increased slightly, but the wear and internal pump leakage, volumetric efficiency decreased significantly, it is difficult to achieve the rated pressure. Hydraulic pump long time work and aggravate the wear, oil temperature rise, resulting in wear of hydraulic components and seals of aging, damage, loss of ability of the seal, hydraulic oil deterioration, finally caused the failure of.

2, the unreasonable selection of hydraulic components. Boom cylinder specifications for 70/40 non - standard series, seal for non - standard parts, high manufacturing cost and seal replacement inconvenience. Boom cylinder bore small, is bound to make the system adjustment for high pressure.

3, the design of hydraulic system is not reasonable. We can see from Figure 1, control valves and hydraulic steering device for series single pump, relief valve setting pressure 16MPa, and the hydraulic pump rated working pressure for the 16MPa. The hydraulic pump is often in the full load or overload for a long time (high pressure) conditions of work, and system hydraulic impact, long-term non oil, hydraulic oil pollution, increased pump wear, so pump pump shell burst (after he was found such failure).