Core tip: Bulldozers must know the bulldozer fault through three cases: after the TY160B bulldozer has been used for a period of time, there is a difficult turn to the left. The fault gradually became serious, and the steering difficulty also occurred on the right side, and the speed of the diesel engine obviously decreased when turning.
The loosening of 1. locking nuts leads to failure of steering
(1) failure phenomenon
After 1 TY160B bulldozers used for a period of time, there was a difficulty of turning to the left. The fault gradually became serious, and the steering difficulty also occurred on the right side, and the speed of the diesel engine obviously decreased when turning.
(2) structure principle
The bulldozer steering is realized through the operation of the brake and the steering clutch. The brake is a mechanical control belt brake, and the steering clutch is a wet type, multi chip, spring pressed and hydraulic separated clutch. The steering clutch is connected by the steering clutch hub, the spline, the lock nut and the rear axle, and the rear axle is supported on the rear axle box through the bearings and bearing seats on both sides. When bulldozers are walking, the rear axle shaft drives the steering clutch on both sides to rotate through the steering clutch wheel hub on both sides.
Steering clutch hydraulic control system consists of steering pump, steering, steering valve and steering clutch separation cylinder. When steering, the pressure oil from the output of the steering pump enters the steering valve. Under the control of the steering valve, the pressure oil passes through the left and right connecting oil pipes into the rear axle bearing seat oil hole (the oil hole is inside the rear axle bearing seat), and then through the oil slot on the outside of the wheel hub of the clutch, the separation cylinder of the left and right clutch is pushed into the clutch cylinder, and the pressure oil is pushed into the separation cylinder of the left and right clutch. The clutch piston of the steering clutch moves and separates the clutch so as to realize the steering of the bulldozer.
(3) troubleshooting
First, check the hydraulic pressure of the transmission to the clutch is normal, which indicates that the steering pump and the steering valve have no fault. The fault may be the leakage of the oil path after the tubing is connected.
Secondly, the O - shaped seal on the left - side tubing is not damaged. The analysis of the fault may occur at the left and right bearing seats, the steering clutch hub, and the clutch cylinder.
Thirdly, the left and right steering clutch is dismantled, and it is found that the locking nut of the left steering clutch hub is loose and the bearing wear of the rear axle is worn, and the wear of the side of the steering clutch hub and the bearing seat is worn out (the matching surface is the position of the oil slot on the rear axle bearing seat and the outside of the clutch hub). The right steering clutch hub locking nut is not loose, but the steering clutch hub and the bearing seat also wear out, only lighter than the left side, and the bearing on the right side of the rear axle is also worn.
Then, the worn steering clutch hub and bearing base are repaired and repaired by pairing.
Finally, replace the new rear axle support bearing and adjust the rear test machine. The steering on both sides of the bulldozer returns to normal.
(4) analysis of the causes
The loosening of the left steering clutch hub due to loosening of the nut on the left steering clutch hub causes the wear of the bearing on the left side of the rear axle shaft. When the left steering clutch hub rotates, it causes friction with the inner surface of the left bearing housing. After the wear of the above components, the gap between the left steering clutch hub and the left bearing seat increases, resulting in the leakage of pressure oil from the face oil hole and the oil groove, so that the left steering clutch can not be separated.
When the left bearing is worn, the right rear axle shaft also has radial runout, resulting in wear on the steering wheel of the right steering wheel and the inner surface of the right bearing block. When the wear occurs, the pressure oil leaks, causing the bulldozer to not turn on the right side.
Stagnation of 2. valve spool leads to failure of steering
(1) failure phenomenon
During the construction of 1 TY320 bulldozers, the bulldozers can not turn around when the operators pull the steering rods on any side. At the same time, the left and right steering rods are pulled, and the bulldozers are still running in a straight line. The preliminary decision is that the steering system has been broken down.
(2) structure principle
The bulldozer adopts hydraulic power assisted steering and braking. The pressure oil output from the steering pump enters the diverter valve after the coarse filter and the fine filter, and is distributed to the steering loop and the braking circuit by the proportion of 3:1 according to the split valve. The pressure of the steering loop is set to 1.25MPa by the sequence valve.
When the steering handle is not manipulated, the pressure oil flowing from the shunt valve to the left and right steering valve is enclosed in the steering valve and turns to the clutch without pressure oil and is in the joint. The left and right steering valves are respectively controlled to separate the left and the right clutches, so that the left and right steering can be realized. At the same time, the left and right steering valves are operated to make the left and right clutches separated simultaneously, and bulldozers are suspended.
(3) troubleshooting
First of all, check the steering rod connection well, the clearance of the rod is suitable, thus eliminating the possibility of the problem of the steering rod.
Secondly, the hydraulic pressure of the steering hydraulic system is measured at 2.3MPa, which indicates that there is no problem with the steering pump.
Again, check the bulldozer braking effect is good, which shows that the bulldozer used for braking and diverting diverting valve of hydraulic oil line is working normally.
Then, the Trinity valve combined with the shunting valve, the sequence valve and the steering valve is detached from the rear axle box lid. It is found that the piston in the sequence valve spool and the spool is stuck.
Finally, the sequence valve and the spool are cleaned to reload the test machine, and the bulldozer steering is restored to normal.
(4) analysis of the causes
The sequence valve is used to adjust the oil pressure of the input clutch cylinder. Because the sequence valve is stuck by impurities, it causes it to be in an overflow state all the time. At this time, the hydraulic pressure of the steering loop is too low, which can not overcome the force of the steering clutch spring, so that the steering clutch can not be separated and the bulldozer can not be turned.
3. hydraulic pump suction air leads to equal gear
(1) failure phenomenon
After the work of 1 TY230C bulldozers working 1600h, there is a "wait" after the start of the bulldozer, that is, after the bulldozer does not walk, it is necessary to wait a period of time to walk. If the bulldozer is still unable to walk after waiting for a period of time, the operator needs to exhaust at the pressure measuring port of the fine filter of the variable speed oil path, and the bulldozer can walk. The movement of the bulldozer after walking is normal.
(2) troubleshooting
First of all, replace the O seal ring of the coarse filter and the oil suction port of the variable speed pump, and the bulldozer's "equal gear" phenomenon still exists.
Secondly, check the oil suction hose of the variable speed pump and press the oil absorption hose. The result shows that the tube has no breakage.
Again, check the transmission pump, found that the skeleton oil seal did not damage, in order to ensure that the assembly does not take place "suction" phenomenon, and replaced 1 new transmission pumps, but the bulldozer "equal gear" phenomenon still exists.
Then, incidentally, when installing the variable speed pump, the oil leakage at the suction port of the steering pump is loose, and the fastening bolts of the steering pump suction pipe are loose.
Finally, replace the O ring of the oil suction port of the steering pump, tighten the locking bolts of the oil suction pipe of the steering pump, and the phenomenon of "equal gear" of the bulldozer vanishes.
(3) analysis of the causes
The cause of "equal gear" may be the intake of air from the suction line of the bulldozer variable speed pump when starting. After starting, the transmission pump will drain oil and exhaust at the side. After the air in the suction pump of the variable speed pump is discharged, the output pressure of the variable speed pump can be established. The bulldozer has a coarse filter on the variable speed oil circuit and the steering oil way, and the position of the oil suction pipe of the steering pump is low, and the position of the oil suction pipe of the transmission pump is slightly higher. The loosening of the fastening bolts of the suction pipe of the steering pump causes the leakage of the suction pipe. When the air is stopped for a period of time, the air enters the suction pipe from the leakage part, and the oil flows into the bottom of the crude oil filter. When the pump is started again, the higher position of the variable speed pump appears to be "suction". The steering pump of the lower position is not obvious due to the phenomenon of "suction", and there is no turning phenomenon.
