Heavy-Duty Caster Carries 50-Ton Loads

Engineers and technicians at Hamilton Caster, Hamilton, Ohio, recently designed and built four 100,000-lb capacity casters for a federal contractor. Fully assembled, each two-wheeled caster towers 4.3 ft. tall and weighs more than 8,000 lb. Casters have a spring-loaded suspension, an eight-position swivel lock for directional control, a 7-in.-diameter oscillating axle to accommodate uneven surfaces, and a foot-operated brake. Hamilton had to use a CNC milling machine to cut two raceways into the mounting plate, one measuring 18-in. in diameter, the other 32 in. To increase wear resistance, both raceways were flame-hardened. The axle, spring pins, and spring block were precision-machined on a CNC lathe. To insert the spring pins into the spring block, Hamilton used dry ice to contract the steel by 0.003 in. to let the spring pins slide into the block.