gear ratio

gear ratio (plural gear ratios)

1. The ratio of the speeds of rotation of the initial and final gears in a gear train.
   • 1962 October, “Beyond the Channel: Italy: New series of E646 electrics”, in Modern Railways, page 276:

     Two versions exist of the new locomotives, for passenger and for freight work respectively, the technical difference between the two lying in the gearing of the bogies; the passenger locomotives, in light green and pearl grey livery, have a 25:64 gear ratio to haul 12-coach, 450-ton trains at 87 m.p.h. on the level, and the freight locomotives, in the famiiar Italian brown livery, have a 20:69 gear ratio enabling them to move 1,500-ton freights on the level at a consistent 53 m.p.h., with a maximum of 68 m.p.h.

• crawl ratio