Abstract: A method and apparatus for monitoring wear associated with a particular cyclically moving part in a machine, the machine comprising a plurality of moving parts and operating in a succession of cycles. Apparatus is provided for generating a first signal at a predetermined position and direction of movement of the moving part, for generating a second signal at a predetermined cyclic position in each machine cycle, for producing a third signal indicative of the interval of time between the first signal and the second signal, and for forming a comparison with a reference signal to determine the extent of wear associated with the particular moving part.