Generally speaking, the main reasons that the DTH rig cannot be lifted with load are:
When running at low speed, the leakage in the pump is serious; When running at high speed, the pump pressure increases slightly. However, due to the wear and internal leakage of the pump, the volumetric efficiency drops significantly, which makes it difficult to reach the rated pressure. Long working hours of hydraulic pumps aggravate wear and oil temperature. As a result, the hydraulic components are worn and the seals are aging and damaged, the sealing ability is lost, the hydraulic oil deteriorates, and finally the failure occurs.
The specifications of the DTH rig boom cylinders are non-standard series, and the seals are also non-standard, so the manufacturing cost is high and the seals are inconvenient to replace. Due to the small diameter of the boom cylinder, the system set pressure is bound to be high.
The control valve and the full hydraulic steering gear are connected in series with a single pump. The set pressure of the safety valve is 16MPA, and the rated working pressure of the hydraulic pump is also 16MPA. Hydraulic pumps often work under full load or long-term overload (high pressure). In addition, the system has a hydraulic shock, and the hydraulic oil is contaminated, which intensifies the wear of the hydraulic pump, causing the pump casing to burst.
There are many hydraulic components on construction machinery, so sufficient hydraulic oil is needed. When the hydraulic oil needs to be replaced due to deterioration due to long use, some people mistakenly believe that only the oil in the hydraulic oil tank needs to be drained and filled with new hydraulic oil. However, there are still a lot of old hydraulic oil remaining in the hydraulic oil pipes and hydraulic control valves at this time. When the DTH rig is used, the mixed use of new and old oil will accelerate the rate of deterioration of the new oil.