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Loader instance analysis in car brake failure

Creation:HOORAY Source:Hooray Machinery Release Time:2016-11-11 17:32

Abstract:One Volvo 220 e loader, when the driver started the engine, after pushing the parking brake switch, switch inside the parking brake lights flickering, the dashboard I - ECU controller parking brake trouble light flashing on the display, the observed frequ
One Volvo 220 e loader, when the driver started the engine, after pushing the parking brake switch, switch inside the parking brake lights flickering, the dashboard I - ECU controller parking brake trouble light flashing on the display, the observed frequent braking hydraulic system for brake livestock can be pressurized. Under normal condition and remove after the parking brake, the light shall be extinguished, it shows that the braking system cannot completely remove the parking brake, existence of intermittent brake failure.

Loader cab

troubleshooting Parking brake can not thoroughly remove the loader, the cause of the existence of intermittent brake may exist in the brake hydraulic system or brake in the electric control system, the troubleshooting methods are as follows.

(1) screening the brake hydraulic system

structure The loader hydraulic braking system with the engine cooling fan driven by Shared one hydraulic pump, hydraulic system of brake hydraulic system is mainly composed of the foot brake valve, brake accumulator, V - ECU controller, P3 pump regulator, pressure valve, cylinder, servo piston, P3 pump, fan motor, brake valve, the valve block, parking brake, servo valve, shuttle valve, steering the priority valve, etc.

The analysis reason If the fault appears in the brake hydraulic system, which may have the following two reasons: one is the brake hydraulic system leak, second, the brake accumulator is damaged.

If hydraulic braking system of the foot brake valve, P3 pump, brake pressure reducing valve and pipeline leak seriously, the brake accumulator charging - 2, parking brake always reach remove parking brake pressure, parking brake will not lift. If there is slight leakage braking hydraulic system, hydraulic system, after stop charging - pressure will reduce rapidly, will lead to the parking brake can't lift and intermittent brake, parking brake lights flickering phenomenon. If the brake accumulator is damaged, brake accumulator cannot make brake system pressure constant, pressure fluctuate, also can cause the parking brake can't lift and intermittent braking, parking brake lights flickering phenomenon.

Screening method for braking hydraulic system leak, the fan motor speed will slow down, cause the engine temperature, it also can be used as the screening based on braking hydraulic system leakage fault. Pressure gauge is used to inspect the brake charging - each part of the hydraulic system pressure is normal, can find the brake hydraulic system leak reasons and positions. Doubt 2 fails, the brake accumulator should detect filling the brake accumulator nitrogen pressure, if filling the nitrogen pressure is low, should replace the brake accumulator.

(2) screening braking electronic control system

Insurance FU15 structure to provide power for the whole circuit, the parking brake switch SW501 controlled by the driver, pressure switch SE503 used to test the brake accumulator, V - controller ECU, I - MA501 ECU to control the parking brake solenoid valves.

Remove the parking brake, the pilot should press the parking brake switch SW501. Parking brake switch SW501 pins for the I - ECU controller P2.15 provide voltage, if the hydraulic braking system is pressurized and pressure switch SE503 cut, the controller I - - ECU controller ECU through the pressure switch SE503 to V signal, V - ECU controller pins EC4 MA501 voltage solenoid, parking brake can lift the brake. At the same time, the V - ECU controller pins EA9 high voltage through pressure switch SE503, parking in the parking brake switch SW501 brake lamp current cut off, insurance FU15 SW501 built-in resistance through the parking brake switch to the parking brake lamp current cut off, parking brake lamp will go out.

The analysis reason If the failure occurs in the brake control system, may have the following two reasons: one is the pressure switch SE503 damage, the second is the insurance FU15 to parking brake switch SW501 damage between the lines.

Screening methods measuring V - ECU controller to the parking brake, electromagnetic valve, MA501 voltage for 24 V, but the voltage is intermittent, I - ECU controller shows the headlights and parking brake switch SW501 parking brake lights into intermittent, also shows that when the pressure of high pressure switch SE503 detected when low, unable to remove the parking brake. Should check whether the pressure switch SE503 is damaged, if damaged replace the switch.

Measure insurance FU15 to parking brake switch SW501 line is open circuit, if break the insurance FU15 can't give I - ECU controller of power supply, I - ECU controller pins P2.15 will no voltage, I - ECU, V - ECU controller cannot give MA501 parking brake solenoid valve power supply. At this time through insurance FU15 to parking brake switch SW501 between the lines, the fault can be lifted.

(3) the comprehensive breakdown

If the brake hydraulic system and brake control system failure is difficult to distinguish, in the brake accumulator pressure gauge, can be detected using multimeter pressure switch SE503 of 1, 2, 3, contact on-off state and V - voltage of ECU controller EA9 stitches. Start the engine, if the pressure gauge is detected within the brake accumulator pressure is too low, that is the brake hydraulic system failure, should check the brake hydraulic system.

If detected pressure gauge pressure can be increased, multimeter can detect pressure switch SE503 contact within 1, 3, get through, if not through, that pressure switch SE503 is faulty, replace the pressure switch SE503 can.

If the test pressure switch after SE503 trouble-free, will remove the parking brake switch SW501 according to location, at the moment I - ECU controller can provide the pins P2.15 voltage, the pressure inside the switch SE503 off contact 1, 3, 1, 2, connect, multimeter is used to inspect to V - I - ECU controller ECU controller whether pins EA9 provide voltage. If can provide voltage, I - in ECU controller can make the lights go out, V - controller ECU to provide electromagnetic valve MA501 voltage, parking brake will be lifted. If unable to provide voltage, explain, V - I - ECU controller ECU controller is faulty, replace the controller.

Thus, according to the above method can detect the Volvo 220 e loader parking brake can't completely remove fault.
 
 

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