Gilson’s Test-Master Screen Shaker delivers accurate particle size separations for large samples and features an easily controlled, integrated hopper for easier introduction of sample material. Vertically hinged front panel doors offer improved access and clearance while reducing nuisance dust. Internal rotating counterweights of the Test-Master® drive system equalize the vertical screening action for smooth, quiet operation. Standard vibration characteristics are designed for coarse materials of mid-range density such as limestone or gravel aggregates. The 1.6ft³ hopper is hinged at the rear and allows the sample to be introduced incrementally as the machine is running. When the hopper is closed, a panel blocks dust from escaping through the opening. A built-in, electronic digital controller has an LED display of time remaining and produces an audible tone at the end of the test cycle. Test cycles lasting up to 99 minutes, 59 seconds can be programmed and cycles may be interrupted without loss of test time. An ergonomically operated foot-pedal easily controls the hydraulic clamping and pressure release system for the screen trays.