Troubleshooting methods for XD120 roller

When an xd120 roller is moving forward, it occasionally gets stuck and won't move (the machine moves backward normally all the time). At this time, just move the machine backward once and then forward, and the stuck phenomenon will immediately disappear.

When this fault occurs, we measure the pressure of the hydraulic drive system with a pressure gauge. If the pressure reaches over 30mpa, it indicates that the pressure of the drive system is too high. Therefore, it is determined that this phenomenon is caused by a mechanical system fault rather than a hydraulic system fault. First, the bearing support part where the steel wheel on the machine connects to the frame was inspected. It is normal here.

Based on the structure of this machine and the working principle of its hydraulic system, after analysis, it is found that since the traveling system of the double steel wheels of this machine is driven by two parallel hydraulic motors, the best way to determine which steel wheel the fault is on is to lift the two driving steel wheels off the ground respectively and let the hydraulic motors drive the steel wheels to rotate. At this point, two situations will occur: If the lifted steel wheel is free of faults, it can idle under the drive of the hydraulic motor. At this time, the pressure in the hydraulic system will not be very high (only the inertia and frictional resistance of the steel wheel need to be overcome). If the steel wheel being lifted is faulty, it should not idle (as it is mechanically jammed), but at this time, the roller will have a tendency to move forward. The following tests were conducted for this purpose: Lift the front frame with a jack to lift the front steel wheel off the ground. Then push the walking control lever in the forward direction. At this point, the machine has a tendency to move forward and push the jack over. The pressure of the hydraulic drive system is approximately 20mpa(the walking pressure is basically normal). After the jack is pushed over, the front steel wheel touches the ground and the machine stops moving. At this point, the pressure of the hydraulic drive system rose above 30mpa. Lift the rear frame with a jack to lift the rear steel wheel off the ground, and then push the walking control lever in the forward direction. The rear steel wheel of the machine is idling, but the machine does not move forward. At this time, the pressure of the hydraulic drive system is approximately 5mpa, indicating that the pressure of the drive system is relatively low. Through the above tests, it can be determined that the fault should be on the front steel wheel.

So, the front steel wheel was disassembled for inspection, and it was found that the middle transmission shaft 5 connected to the eccentric shafts 3 on both sides of the wheel was damaged (see Figure 1). A 200mm long broken shaft fragment is adsorbed onto the side plate 1 of the steel wheel by a magnetic oil drain plug 2. The diameter of this fragment is slightly larger than the gap δt between the side plate 1 of the steel wheel and the eccentric shaft 3. When the machine is running, since the eccentric shaft does not rotate (when the machine is not vibrating), the adsorbed debris rotates along with the steel wheel. When it touches the fixed eccentric shaft, as the debris is adsorbed by the magnet, if it passes over the eccentric shaft, the steel wheel can continue to rotate. Once in a special situation, when this fragment is stuck between the side plate of the steel wheel and the eccentric shaft (δt) like a wedge, a braking effect is produced. At this time, the machine cannot move forward, but it can still move backward. When the machine moves backward, the "wedge" will exit from the gap (δt). When the machine moves forward again, the fault phenomenon may not occur immediately. Because the probability of such a malfunction occurring is extremely low, it is somewhat difficult to make a judgment.

After the maintenance of the intermediate drive shaft, the fault was eliminated during the installation and test run.