Kalmar DRT450 Reach Stacker Brake Pressure Low Alarm Repair
Fault description
Kalmar DRT450 front crane alarms when the brake pressure is low, the handbrake cannot be turned on, and the locomotive cannot run.
Troubleshooting
First, use the built-in diagnostic menu of the Kalmar device to check the handbrake button switch, and it works normally. Then check that the handbrake solenoid valve coil and power supply work normally, no short circuit or open circuit is found. Use the external hydraulic pressure to check that the charging pressure of the accumulator is zero, and it cannot be charged to 200bar, which is abnormal. It is initially suspected that the accumulator, brake pump or charging valve malfunctions are causing the above problems.
Since the charging pressure of the measured accumulator is zero, the cooling oil return pressure at the wheel side of the front axle is only 1 bar. It is impossible to check the normal charging pressure of the brake pump. However, the oil output pipe of the brake pump is very large, and the brake pump problem is temporarily ruled out. Check that there is no hydraulic oil coming from the accumulator charging oil pipe, disassemble the charging valve, and find that the upper constant pressure valve of the charging valve is stuck by iron filings.
Solution
Completely disassemble the charging valve, remove the iron filings in the charging valve, replace the brake high-pressure filter element, reinstall the charging valve, and the test run is normal.
Summary
In the reach stacker brake charging system, the brake pump sends the brake hydraulic oil to the charging valve. The charging valve core is closed so that the brake pressure oil is charged to the accumulator until the accumulator pressure reaches 200 bar set by the system, and then The charging spool opens and the constant pressure valve opens. After the hydraulic oil of the brake pump is sent to the wheel side of the front axle to cool, it returns to the brake oil radiator or directly to the brake oil tank.
In this example, because the constant pressure valve is stuck by iron filings and is normally open, the brake hydraulic oil is directly cooled to the front axle wheel and cannot be sent to the accumulator for charging.
In addition, replace the brake high-pressure filter, clean the charging system, and try to ensure that no iron filings are mixed in the hydraulic system.