How to deal with the failure of the small loader attachment bucket
Posted: Dec 19th, '24, 21:54
Fault analysis: According to the linkage mechanism of the working device, when the bucket is in the retracted state and the operating handle of the pilot valve is in the middle position, the large chamber of the bucket cylinder is pressurized due to the deadweight of the bucket; at this time, as long as the pressure oil of the large chamber leaks relative to the oil return port, the bucket will automatically tilt forward.
There are six ways to cause the oil in the large chamber of the bucket cylinder to leak to the oil return port:
First, there is obvious leakage from the pipe fittings, joints and installation joints between the large chamber of the bucket cylinder and the distribution valve.
Second, the valve stem of the bucket reversing valve of the distribution valve fails to return to the middle position (due to the valve stem of the reversing valve being stuck, the valve core of the large chamber pilot valve of the bucket being stuck and unable to reset, and the valve body of the large chamber pilot valve of the bucket having sand holes and internal leakage), so that the small chamber of the bucket cylinder is connected to the pump port, and the large chamber is connected to the oil return port.
Third, when the bucket cylinder leaks internally, the small chamber of the bucket also leaks relative to the oil return port.
Fourth, the pressure of the large chamber overload valve of the bucket cylinder is too low (caused by the broken pressure regulating spring, the valve core is stuck in the open position with dirt, the valve body has sand holes or grooves that communicate with the return oil chamber, etc.).
Fifth, the large chamber oil replenishment valve of the bucket cylinder is leaking (caused by the broken reset spring, the valve core is stuck in the open position with dirt, the conical surface of the valve core and the valve body has dirt or groove defects, the valve body has sand holes that communicate with the return oil chamber, etc.).
Sixth, the reversing valve core or valve hole is excessively worn, making the matching clearance between the valve core and the valve hole much larger than the design value, causing the large chamber pressure oil of the bucket cylinder to leak.
To eliminate the bucket failure, the above six leakage paths should be developed:
① Among the above six leakage situations, the simplest and easiest to judge is the first situation: start the small loader and lift the boom to a certain height, retract the bucket to the maximum position, and observe whether there is obvious leakage between the pipe fittings, joints and installation joints between the large chamber of the bucket cylinder and the distribution valve.
②If there is no external leakage in the first case, the second case can be judged: start the small loader and operate the pilot valve handle to raise the boom to the highest position and the bucket to the maximum position → turn off the engine and remove the pilot pipes at both ends of the distribution valve bucket valve stem. At this time, if the bucket drop phenomenon disappears, it can be determined that the distribution valve bucket valve stem does not return to the middle position due to the pilot valve, causing the bucket drop phenomenon. The pilot valve should be disassembled and cleaned or replaced. Otherwise, the third case should be judged!
③For the third case, we can make some simple judgments: start the small loader and operate the pilot valve handle to lower the boom to the lowest position and the bucket to tilt backward to the maximum position → turn off the engine and open the large cavity hose of the bucket cylinder and lead it back to the hydraulic oil tank → start the machine and operate the pilot valve handle to tilt the bucket backward → observe whether there is continuous hydraulic oil coming out of the large cavity oil port of the bucket cylinder. If hydraulic oil continues to come out at this time, it means that the bucket cylinder has serious internal leakage and needs to be disassembled, repaired or replaced. If the cylinder has no internal leakage, the fourth and fifth situations should be further analyzed.
④ For the fourth and fifth situations, we can use the pressure detection method to determine: connect a pressure gauge with a range of 0-25MPa to the pressure measuring port of the large chamber of the bucket cylinder → start the machine → operate the pilot valve handle to make the bucket in the maximum forward tilt position → increase the throttle and operate the pilot valve handle to lift the boom, while observing that the reading of the pressure gauge during the boom lifting process should reach the design value (22MPa). Otherwise, one or both of the two leakage situations are true, and the large chamber overload valve or oil replenishment valve of the bucket cylinder should be disassembled and cleaned.
⑤ If the bucket drop phenomenon does not disappear when the first to fifth situations are excluded, the machine should be stopped, the boom and bucket are lowered to the lowest position, the bucket valve stem of the distribution valve should be disassembled, and the valve stem and valve hole and their matching conditions should be carefully checked, etc.
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for more info just visit our website at www.dig-dog.com
contact # : +86 158 6218 2088
email : sales@bonovogroup.com
There are six ways to cause the oil in the large chamber of the bucket cylinder to leak to the oil return port:
First, there is obvious leakage from the pipe fittings, joints and installation joints between the large chamber of the bucket cylinder and the distribution valve.
Second, the valve stem of the bucket reversing valve of the distribution valve fails to return to the middle position (due to the valve stem of the reversing valve being stuck, the valve core of the large chamber pilot valve of the bucket being stuck and unable to reset, and the valve body of the large chamber pilot valve of the bucket having sand holes and internal leakage), so that the small chamber of the bucket cylinder is connected to the pump port, and the large chamber is connected to the oil return port.
Third, when the bucket cylinder leaks internally, the small chamber of the bucket also leaks relative to the oil return port.
Fourth, the pressure of the large chamber overload valve of the bucket cylinder is too low (caused by the broken pressure regulating spring, the valve core is stuck in the open position with dirt, the valve body has sand holes or grooves that communicate with the return oil chamber, etc.).
Fifth, the large chamber oil replenishment valve of the bucket cylinder is leaking (caused by the broken reset spring, the valve core is stuck in the open position with dirt, the conical surface of the valve core and the valve body has dirt or groove defects, the valve body has sand holes that communicate with the return oil chamber, etc.).
Sixth, the reversing valve core or valve hole is excessively worn, making the matching clearance between the valve core and the valve hole much larger than the design value, causing the large chamber pressure oil of the bucket cylinder to leak.
To eliminate the bucket failure, the above six leakage paths should be developed:
① Among the above six leakage situations, the simplest and easiest to judge is the first situation: start the small loader and lift the boom to a certain height, retract the bucket to the maximum position, and observe whether there is obvious leakage between the pipe fittings, joints and installation joints between the large chamber of the bucket cylinder and the distribution valve.
②If there is no external leakage in the first case, the second case can be judged: start the small loader and operate the pilot valve handle to raise the boom to the highest position and the bucket to the maximum position → turn off the engine and remove the pilot pipes at both ends of the distribution valve bucket valve stem. At this time, if the bucket drop phenomenon disappears, it can be determined that the distribution valve bucket valve stem does not return to the middle position due to the pilot valve, causing the bucket drop phenomenon. The pilot valve should be disassembled and cleaned or replaced. Otherwise, the third case should be judged!
③For the third case, we can make some simple judgments: start the small loader and operate the pilot valve handle to lower the boom to the lowest position and the bucket to tilt backward to the maximum position → turn off the engine and open the large cavity hose of the bucket cylinder and lead it back to the hydraulic oil tank → start the machine and operate the pilot valve handle to tilt the bucket backward → observe whether there is continuous hydraulic oil coming out of the large cavity oil port of the bucket cylinder. If hydraulic oil continues to come out at this time, it means that the bucket cylinder has serious internal leakage and needs to be disassembled, repaired or replaced. If the cylinder has no internal leakage, the fourth and fifth situations should be further analyzed.
④ For the fourth and fifth situations, we can use the pressure detection method to determine: connect a pressure gauge with a range of 0-25MPa to the pressure measuring port of the large chamber of the bucket cylinder → start the machine → operate the pilot valve handle to make the bucket in the maximum forward tilt position → increase the throttle and operate the pilot valve handle to lift the boom, while observing that the reading of the pressure gauge during the boom lifting process should reach the design value (22MPa). Otherwise, one or both of the two leakage situations are true, and the large chamber overload valve or oil replenishment valve of the bucket cylinder should be disassembled and cleaned.
⑤ If the bucket drop phenomenon does not disappear when the first to fifth situations are excluded, the machine should be stopped, the boom and bucket are lowered to the lowest position, the bucket valve stem of the distribution valve should be disassembled, and the valve stem and valve hole and their matching conditions should be carefully checked, etc.
Choose DIG-DOG for high-quality, customizable brush cutters for skid steers with fast delivery. Contact us today to discover how our superior products can enhance your land management tasks!
for more info just visit our website at www.dig-dog.com
contact # : +86 158 6218 2088
email : sales@bonovogroup.com