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This paper describes that the effect of surface texture of sealing lip on lubrication and sealing performance examined experimentally on practical aspect. Hub seals of PAC type were used in this study. A test apparatus and operating procedure were shown. The seal which had texture on the lip had lower frictional torque than plain one. The effect of friction reduction with the textured surface preserved up to 15 cycles, which was equivalent to a travel distance of 30,000 km. The textured surface 10 μmRz with grease on the lip kept sealing performance up to -0.10 MPa in static and dynamic conditions. The endurance time of sealing of the textured surface was almost the same as that of the plain surface in seal endurance test with muddy water.

This paper describes a new measurement method using fluorescence analysis to measure oil pump rates of radial lip seals for small shaft diameters. A test apparatus and operating procedure for measurement of pump rate were shown. First results of pump rates obtained with seals for 8 mm shaft diameter were shown. As a result, the oil pump rates under various shaft speeds and sump pressures ranged from 4 to 160 mg/h.

We developed a measurement method to evaluate the sealing performance for narrow gap between a metal shaft and a fitted sleeve quantitatively in a brief time. We examined the effect of the chamfer shape and the surface roughness of the shaft on the leakage rate. We also conducted liquid leakage test in order to compare the leakage rate of gas with that of the liquid. From this comparison, we showed that it is possible to evaluate the sealing performance for liquid by measuring leakage rate of gas. In addition, we discussed the leakage rate of fluid through the gap by assuming viscous flow. The estimated leakage rate of the liquid derived from the leakage rate of air by converting viscosity of air into that of the liquid was totally proportional to the measured leakage rate of the liquid. Therefore, we concluded that the leakage rate of liquid can be estimated by measuring that of air.