In a hydraulic chain tensioner for an engine timing drive, an annular groove is formed on an outer circumferential surface of a plunger, and a friction ring is disposed in the groove. The donor-side transceiver unit, when the service-side signal has been received, measures the signal level of the service-side signal at the first frequency band. The passage defines a gap distance in a width direction between the straight sides at the passage inlet. The two connector rings are interconnected by an adjustable-length isolator strap which limits the range of motion of the user’s elbow. Additionally, a software entity permits high bandwidth simulation of design components normally requiring cycle accurate simulation.