Quartering is the term for setting crankpins of locomotive drivers at 90 degrees ‘crank’ apart (similar to an automobile crankshaft). Accurate quarter of all drivers in a set to the same angle (whether exactly 90 degrees or not) is critical for smooth operation of model locomotives. This economical yet precision tool enables quick, accurate quartering of HO and S size drivers up to 1” O.D. on 1/8” or 3mm axles. The wheel is located onto the axle while the wheelset is securely held in the tool avoiding possibility of slippage while wheel is pressed on with arbor press or similar. Can also be used to compare quarter of existing driver sets.