After a station CAT330CL type backhoe was buried landslides, maintenance personnel overhaul was carried out. But after the overhaul work on aircraft temperature above 25 ℃ ambient temperature to reach thermal status, its mining, walking, and rotating actuator movement is getting slow.
1 tape round 2. Tape 3. Bolts 4. Idler pulley 5. Tensioners 6. Compressor belt pulley 7. Generator tape round 8. Driving wheel
2 Preliminary analysis and troubleshooting
According to empirical analysis , resulting in the failure phenomenon there are two possibilities: First, the hydraulic system components and seals fail , when the temperature rise in the hydraulic system leak ; Second, the state underpowered engine heat .
First measurement of the hydraulic system of pumps , valves, hydraulic and found no abnormalities . Measuring the hydraulic system oil temperature 90 ℃, is normal , then ruled out the possibility of hydraulic system failure .
Then the engine oil system , intake and exhaust system checks showed no abnormalities ; measurement of high temperature heat sink . Analysts believe that the high temperature is likely to be the cause of the engine power down and the whole movement slow .
3 Again analysis and troubleshooting
High engine water temperature usually has five kinds of possibilities: First, the pump does not turn or bad job , the second is delayed thermostat opens, the third is a lot of dirt or external radiator internal blockage , the four -cylinder pad has a slight leak , five fan speed is decreased . For more than five possible one by one investigation :
First, start the engine , radiator Shui observation room has swirling water , no bubbles , which illustrate the pump is working properly and cylinder head gasket intact.
Secondly, check the thermostat to be demolished , and found no abnormalities .
Again, careful examination of the outside of the radiator , radiator cleanliness good find .
Finally, the fan speed is measured and found the engine and fan speed is different, as shown in the table.
|Engine at different speeds measured fan speed (r / min)|
Schedules can be seen from the data , there is a fan belt slipping . To further validate this inference , in the engine shutdown, hand pull tape and found the tape loose . The engine driving wheel 8 through tape 2 tape drive wheel 7 generators , air conditioners, tape and tape round a wheel 6 , on the outside of the tape with a tension wheel 5 to the tape tension . Another tape idler 4 for guidance. Tensioners for tensioning device adaptation means 5 , no manual adjustment function , and the compressor and the generator is fixed in position .
Perform the following troubleshooting for tape slack :
First, check the aircraft loaded tape 2 is a multi- wedge belt factory , there is no mismatch . Secondly , the tape tensioning device is also normal view . Again, there are changes examination revealed traces of the bracket between the generator and the air conditioning compressor.
Originally, generators and compressors are fixed by the bracket support. After the machine has been buried , the stent was broken , so maintenance personnel in the repair process instead of random and got a piece of iron , and changed the original installation location, so that the distance between the generator and the compressor is reduced . After installing the tape tape tension decreases, the process is running , the cooling effect of the radiator is weakened , resulting in decreased engine power .
Re- measurement, making the generator and air-conditioning compressor bracket between the engine and then install it on the test machine , the machine high water temperature , slow disappears.