A relatively small object, measuring about 1 x 3.5 inches when assembled, Ranger VIII’s Hydraulic Timer was a spring-loaded instrument that activated various mechanical switches aboard the Ranger spacecraft on command from mission control. The hydraulic timer served as a fail-safe device should the electric sequence fail and as the primary timer for some of the Ranger spacecraft’s minor operating systems. The timer was loaded with oil prior to takeoff and functioned by forcing oil, at specified rates, through a tube to active the copper springs which activated the mechanisms.
NASA's Jet Propulsion Laboratory transferred this object to the Smithsonian Institution in 1969.
Gift of William A. Saley