Friction testing apparatus and method

A test apparatus 1 for measuring the frictional properties of a fluid, or the properties of a specimen immersed in a fluid, comprising;

• a first specimen holder 10 which is adapted to hold a first specimen 13 in the fluid being tested, such that a first specimen surface of the first specimen 13 is in contact with a second specimen surface of a second specimen 14, in a second specimen holder 15, means for applying a measurable load between the two specimens, said test apparatus 1 also comprising oscillatory driving means for oscillating the first specimen holders along a first direction with respect to the second specimen holder, and a force measuring means 24 to measure the frictional force between the two specimens, characterised in that the apparatus 1 includes a sealed pressure chamber 4 in which the first and second specimen holders 10, 15 are located so that the test may be carried out under alternative pressures, and wherein a push rod 9 is provided which connects the oscillatory drive means to the first specimen holder 10 and provides the oscillating motion of the first specimen holder 10 inside the pressure chamber 4 by means of a seal means 18a, 18b so the pressure in the pressure chamber 4 is maintained during the test.