Roller Set Converts Standard Track into a Locomotive Test Stand

Use these miniature roller sets to break in, tune up and test your HO and On30 locomotives. Simply place between your track and the powered wheelsets of your engine, then turn up the power. Metal sideframes conduct electricity from rail through roller bearings to wheel. Now your locomotive does its work while standing still! Makes it easy to detect, isolate and repair erratic operation so your locomotives will run smoother than ever before. Also great for putting steam locomotives on display...shows off all that rod and valve motion, and lets smoke units work at full power. Works with straight DC or DCC power. Assembled, set of 4.