This single output controller is selectable for static testing of a loco on integral, adjustable roller sets or moving tests on layout tracks. The roller assemblies are slid into positions approximating to the locos axle spacing, the loco is then set carefully down, with each wheel engaging snugly into its roller assembly. With the selector switch set to test the control knob is used to apply power to the rollers. The ammeter will register the power consumption of the loco. Moving tests under load - gradients, heavy trains etc. - can be made with the selector switch set to track whilst the unit is connected to a layout. In this mode the LT can of course be used as a conventional controller with a full 1 amp available at the 12v D.C. controlled output as well as the 16v A.C. output for accessories.