Analysis of oil channeling in the shaft head of Hydraulic Gear Pump of loader
"Gear pump flowing oil", that is, hydraulic oil will penetrate the skeleton oil seal overflow, into the gearbox, resulting in the transmission box hydraulic transmission oil mixed with hydraulic oil, affecting the normal work of gearbox torque converter, in order to facilitate the solution of the problem, analyzed the gear pump oil seal oil change fault cause and control method.
1. Impact of parts manufacturing quality
(1) Sealing quality.
Such as oil seal lip geometric failure, tightening the spring too loose, resulting in air tightness test leakage, gear pump installed in the main engine after the flow of oil. The oil seal should be replaced and the material and geometry should be tested.
(2) gear pump processing, assembly.
If the gear pump processing, assembly problems, lead to the gear axis and the front cover of the heart of the different heart, will cause oil partial wear. At this time, the pin hole symmetry, displacement and coaxiality of the front cover bearing hole should be checked.
(3) sealing ring materials and processing quality.
If such a problem occurs, it will lead to cracks and scratches in the sealing ring, resulting in lax or even failure of the secondary seal, and the pressure oil enters the sealing frame (low-pressure channel), so that the oil seal channels oil. At this time should check the sealing ring material and processing quality.
(4) processing quality of variable speed pump.
The feedback information from the main engine factory and the gear pump assembly plus the gear pump oil seal oil transmission problem is more serious, so the processing quality of variable speed pump has a greater impact on channeling oil. Variable speed pump is installed on the transmission output shaft, gear pump through the variable speed pump port positioning and installed on the transmission output shaft, if the variable speed pump end face and gear rotation center runout tolerance (verticality), the gear shaft rotation center and seal center does not coincide, affecting the seal. Variable speed pump processing, trial production process, should check the coaxiality of stop center and stop end face runout.
(5) The seal between the CBG gear pump oil seal and the oil return channel seal is not smooth, resulting in the pressure rise here, so as to penetrate the skeleton seal. Through the improvement here, the phenomenon of pumping oil has been significantly improved. The structure of the form is shown in Figure 1.
2 Gear pump and host installation quality influence
(1) Gear pump and host installation requirements coaxiality is less than 0.05.
Usually the working pump is installed in the variable speed pump, the variable speed pump is installed in the gearbox. If the transmission or variable speed pump end face spline shaft center runout runout error, the formation of cumulative error, resulting in the gear pump at high speed rotation under radial force, resulting in oil seal oil.
(2) Whether the clearance installation between components is reasonable.
External gear pump gear box and gear pump spline and internal spline, the gap between the two reasonable, all the oil has an impact on the gear pump oil. Because the inner and outer block belongs to the positioning part, the clearance should not be too large; Internal and external splines are transmission parts, and the clearance should not be too small to eliminate interference.
(3) gear pump oil and its spline key is also related.
Due to the gear pump shaft extension spline and gearbox output shaft flower groove effective contact length is short, and the gear pump torque transfer work is large, spline under large torque extrusion wear or rolling key, produce huge heat, resulting in skeleton oil seal rubber lip burn, aging, resulting in oil breakthrough. It is recommended that Oems use gear pumps to check the spline strength of the gear pump shaft to ensure adequate effective contact length.
3. The influence of hydraulic oil
(1) The cleanliness of hydraulic oil is too poor, pollution of large particles, sand and slag in various hydraulic control valves and pipelines are also one of the reasons for pollution.
Because the gap between the shaft diameter of the gear shaft and the inner hole of the seal ring is very small, the larger solid particles in the oil enter between them, resulting in the wear of the inner hole of the seal ring, scratch or rotate with the seal ring. Shaft, resulting in the pressure oil of the secondary seal into the low-pressure zone skeleton seal), resulting in seal breakdown, at this time should be filtered or replaced with a new anti-wear hydraulic oil.
(2) After the viscosity of hydraulic oil is reduced, the oil becomes thinner. In the case of higher gear pump pressure, leakage through the secondary seal clearance increases. As there is no time to return oil, the pressure in the low pressure area rises, and the oil seal is damaged. It is recommended to test oil regularly and use anti-wear hydraulic oil.
(3) the host load working time is too long, when the tank surface is low, the oil temperature can be raised to 100℃, resulting in oil thinning, oil seal lip aging, resulting in oil flowing; The liquid level of the tank should be checked regularly to avoid high oil temperature.
