Method of testing the lubrication properties of a liquid

Claim 2

Apparatus for testing the lubrication properties of a liquid comprising a casing, a plate rotatably mounted on the casing, a framework including first and second frame members, a resilient member secured at one end thereof to said framework intermediate said first and second frame members and carrying at its free end a probe extending from the plane of the framework, the resilience of said resilient member permitting said probe to move angularly relative to said first and second frame members in the plane of the framework but resisting angular movement of the probe relative to said first and second frame members at right angles to the plane of the framework, the framework being pivotally mounted on the casing at a part of the framework remote from said probe and said part of the framework being positioned above said plate so that, by pivoting the framework, the probe can be urged into contact with the plate, means acting on said framework adjacent said probe to pivot the framework and urge said probe into contact with the plate, and sensing means associated with the framework and the free end of said resilient member and operable, in use, to detect angular movement of the probe relative to said first and second frame members in the plane of the framework when the frictional heat developed between the probe and the plate destroys a film of said liquid of predetermined thickness on the plate so that the probe is caused to move in the plane of said framework with the plate.

Claim 3

Apparatus as claimed in claim 3 wherein said framework can be removed from the casing.

Claim 4

Apparatus as claimed in claim 3 wherein the shear center of the resilient arm is in the same plane as the free end of said probe so that, in use, when a frictional force is developed between said probe and said plate there is no tendency for said arm to twist about the longitudinal axis of the arm.

Claim 5

Apparatus as claimed in claim 3 wherein said sensing means comprises a sensing coil and a pin, the arrangement being such that angular movement of the probe relative to said first and second frame members in the plane of the framework causes relative movement between said pin and said coil and the arrangement further being such that relative movement between said pin and said coil induces an impulse in an external circuit through the coil.

Claim 6

Apparatus as claimed in claim 3 wherein said sensing means is a capacitor, one plate of the capacitor being fixed and the other plate of the capacitor being movable relative to said one plate in response to angular movement of the probe relative to said first and second frame members in the plane of the framework.