PURPOSE: To produce a new oil film on the contact face of both male and female members constantly by applying pulsating hydraulic pressure to plural oil basins when the female member is moving relatively, on members inscribed in the title which are applied for a loading ram or a cylinder of a material testing machine.

CONSTITUTION: Plural oil basins, 3, 4, 5, independent each other, are provided on inner periphery of a cross section of a portion in which a female member 1 contacts slidably to a male member 2. And respective oil basins 3, 4, 5 are connected to pulsating hydraulic pressure supply sources 6, 7, 8, independent each other, via oil passages 9, 10, 11. And waveforms of pulsating hydraulic pressure are made to be in sine wave all similar in shape, and besides phases are made to move to inner periphery direction in cross section of the female member 1 by a fraction of the total number of the oil basins 3, 4, 5, then new oil films are surely made constantly. When the female member 1 is made to be a cylinder and the male member 2 is made to be a ram, high sensitive material test with scarcely little friction error can be done by applying them to a loading cylinder and a ram.