Purpose -The purpose of this paper is to investigate experimentally slippers, which have an important role on power dissipation in the swash plate axial piston pumps. Since slippers affect the performance of the system considerably, the effects of surface roughness on lubrication have been studied in slippers with varying hydrostatic bearing areas and surface roughness. Design/methodology/approach -An experimental set-up was designed to determine the performance of slippers, which are capable of increasing the efficiency of axial piston pumps, in different conditions. Findings -The findings suggest that the frictional power loss has been caused by surface roughness, capillary tube diameter, and the size of the hydrostatic bearing area, supply pressure and the relative velocity. In the case of the 0.7 and 9.5 mm surface roughness more power is needed to overcome the friction force between slippers and slipper plates, but less power loss occurs with the slippers with surface roughness of 1.5 mm. The slippers with surface roughness of 1.5 mm are considered, because of the optimum power loss. Moreover, the power loss decreases with increasing capillary tube diameter and supply pressure. Originality/value -In order to investigate slipper behaviour under different operating conditions, with different capillary tube size and supply pressure an experimental work was carried out for finding exact design parameters of the real time system.
Currently, graphene is used in aluminum matrix composite manufacturing due to its superior mechanical properties. However, few detailed studies exist on the effect of the process conditions such as sintering temperature (TS), time (tS), and a number of graphene nanoplatelets. Therefore, the effects of different sintering times (tS = 60, 120, 180, 300 min), sintering temperatures (TS = 550, 600, 630℃), and graphene addition (0.1, 0.3, 0.5 wt%) on apparent density and hardness were reported in detail in this study. The crystal structure and microstructure of fabricated composites by powder metallurgy method were examined with X-ray diffractometer and scanning electron microscopy. Apparent density and mechanical properties were tested by density meter and micro Vickers hardness tester. The results indicated that the best sintering time, sintering temperature, and graphene addition were determined to be 180 min, 630℃, and 0.1 wt%, respectively, for the best hardness of composite. The hardness of composite increased from 38 to 57 HV when compared with pure aluminum under the best process conditions.
The paper presents the results of an experimental and theoretical investigation of the effect of clamping ratio and orifice size on the performance of slippers in axial piston pumps and motors. Polishing of the running face to a slightly convex form appears to be essential for successful operation under all conditions. It is shown that slippers operate perfectly satisfactorily with the orifice blanked and, indeed, are generally most stable in this condition. Introduction of the orifice in under-clamped slippers increases the clearance. However it can also destabilise the slipper resulting in the slipper becoming sensitive to the effect of tilting couples. The effect on overclamped designs is more complex depending on the precise value of clamping ratio and on the width of the slipper land.
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