Fault phenomenon: Xugong QY20B crane rotates fast and slowly。
Fault description: get on the train and rotate fast while slow. Observe that the pressures on both sides are different during field operation.
Cause analysis of failure:
1: The positioning screw of the rotary buffer valve stem is loose.
2. A one-way valve at the back of the rotary buffer valve is not tightly sealed, resulting in leakage of pressure oil in one direction.
3. The shuttle valve in the overload overflow valve of the rotary buffer valve is not tightly closed, resulting in leakage of pressure oil in one direction.
Troubleshooting steps and methods:
1: adjust the stem positioning screw of the solid rotary buffer valve.
2. Check the one-way valve behind the rotary buffer valve.
3. Overhaul shuttle valve of overload overflow valve of rotary buffer valve.
Speaking of which, QY70KC is most satisfied with its 48m arm length. Five-section main boom, single-plate boom head and compact boom tail, the lifting performance is 9% ahead of the industry's new products of the same ton level, and the high-frequency working condition performance of the medium and long boom and full reach is 10% to 15%. This allowed him to calmly deal with various engineering conditions. Quick shot, quick boom, strong micro-movement, and high efficiency can bring him high value and high return.
In terms of hoisting performance, QY70KC is also outstanding. Let’s take XCMG’s old model QY70K for comparison. The QY70KC lifting jib (when fully extended to 48m) can be used at an elevation angle of nearly 40 degrees. The range can be up to 36m and the lifting height is up to 31m. ) In this case, the maximum lifting capacity can still reach 1.6 tons. The old QY70K has a maximum lifting height of 25m and a maximum lifting weight of only 0.7 tons at full boom (44.5m), full counterweight (6t) and 36m range. In comparison, the high performance of QY70KC is self-evident.
QY70KC has many counterweights and long poles, which is very advantageous. The arm length can reach up to 48m. Compared with the old QY70K (arm length 44.5m), the maximum lifting height can be nearly 5m different at the same range! Don't underestimate this gap, you really have to encounter some tricky tasks, even if you can't send it up by 1 meter.
In terms of handling performance, QY70K has also been unanimously recognized. QY70K adopts G-generation dual-variable pump + valve post-compensation load-sensing system, dual pumps are automatically divided and combined for control, and the operating efficiency is industry-leading. In other words, the hydraulic system of QY70K can control the engine power and the pumping flow of hydraulic oil in real time according to the driver's hoisting intention. In layman's terms, the system can "give" as much power and flow as "used". , No ink, no waste!
Post time: Aug-21-2020