The role of energy storage in the engine suddenly stalled, the output of the brake pump failure or insufficient oil pressure to provide adequate hydraulic brakes to the truck driver can be achieved in an emergency parking brake. In this paper, a type of internal combustion forklifts for example, described accumulator alarm device working principle and troubleshooting methods.
1 Working Principle
Accumulator alarm device structure as shown in drawings, which consists of a one-way valve, the oil chamber 2, the energy storage spring 3, 4 and low pressure alarm switch valve five other components.
A one-way valve 2 oil storage tanks 3. Storage spring 4 low pressure alarm switch 5. Safety valve 6. Tank
Brake pump output pressure oil through a one-way valve into the oil chamber 2, the energy storage spring 3 compression, which can be converted to oil pressure spring 3 is compressed storage potential . The role of a one-way valve prevents fluid backflow from the entrance of the oil pressure .
4 is a low-pressure alarm switch diaphragm normally closed switch , when the oil pressure in the oil chamber 2 is higher than 3.9MPa , the low pressure alarm switch off the alarm circuit is cut off to stop the alarm .
In order to limit the accumulator pressure values within a safe range , the system safety valve 5 . When the oil pressure in the oil chamber 2 exceeds the set value of the safety valve 5 (13MPa) , the unloading valve 5 , the discharge of the oil flows back to the tank 6 .
When the forklift driver depressing the brake pedal, if the brake hydraulic pressure is supplied is too low, storage potential compression spring 3 is released , the oil in the oil chamber 2 into the brake hydraulic pressure , the brake hydraulic pressure to provide the necessary .
The truck is equipped with energy storage devices at boot time , the alarm is usually in the alarm state . The reason is that the truck has just started, the oil pressure in the oil chamber 2 is too low. At this time , the truck driver should start the engine , the truck parking state, the brake foot pedal in the end 3 to 5 times to turn off the brake . Brake valve is closed, the hydraulic oil chamber 2 increases , the alarm automatically disarm the alarm.
2 troubleshooting techniques
Accumulator alarm device failure usually have two kinds : one alarm alarm signal is not lifted, the second is always no alarm .
( 1 ) does not relieve the alarm signal
Fault performance for the truck starts, the state with their feet in the parking brake pedal in the end will be 3 to 5 times , the alarm has not lifted. The reason may be one-way valve blockage, system leakage , low pressure safety valve or alarm failure , the investigation method is as follows :
First, connect a pressure oil export position of the range of 20MPa pressure gauge , oil pressure accumulator to observe changes .
Second, check the check valve is clogged. Foot brake pedal in the end 3 to 5 times , if the oil pressure gauge pointer does not change, then the check valve clogged by dirt , oil can not enter the oil chamber , the check valve needs to be cleaned . If it is still clogged after cleaning , it should be replaced.
Again, check the system for leaks. Foot brake pedal 3 to 5 times, though if the oil pressure gauge pointer change, but change is slow and not up to 3.9MPa, there may be an accumulator housing or valve leakage caused , need to find a leak oil spots , and replace damaged parts.
Then a test set pressure relief valve . Foot brake pedal 3 to 5 times , if the oil pressure increased rapidly , but the pointer reaches a predetermined pressure value (13MPa) until suddenly stops , indicating that the low pressure valve unloading , that did not meet the accumulator value before the safety valve has begun to drain . This time must be cleaned , and then re-tune to fix their unloading pressure .
Finally, check the low pressure alarm switch. If the pressure reaches 13MPa still alarm , then the low pressure alarm switch is damaged , need to be replaced.
( 2 ) No alarm annunciator
Fault performance for the truck parked for a long time after the engine is started multiple occurrences of alarm does not phenomena . The reason may be the low pressure alarm switch, alarm or related circuit fails , the investigation method is as follows :
First, connect a pressure oil export position of the oil pressure gauge range of 20MPa , followed by an additional drain switch. Open the drain switch, the accumulator in the gradual release of the oil , so that pressure gauge shows the pressure value slightly lower than 3.9MPa.
Second, check the low pressure alarm switch is damaged. After starting the engine if the alarm alarm , then the low- pressure alarm switch and the alarm sound , and the accumulator and the brake pressure maintaining good performance. If the alarm does not alarm , you need to replace the low pressure alarm switch, repeat the check again . If you replace the low pressure alarm switch to the alarm , indicating low pressure alarm switch is damaged . If replacement of the low pressure alarm switch still no alarm , then the alarm circuit or alarm malfunction.
Finally, check the alarm circuit and alarm malfunction. Use test light or multimeter check whether the alarm is energized . As it was electric, can be identified as alarm failure, should be repaired or replaced . As it may not electricity, compared to the alarm circuit breaker , breaker should piecewise find parts .