Super Heavy Duty Casters is designed for the heaviest caster applications. Modification can be made to provide 20,000 lbs. capacity per caster when needed. extra heavy duty caster is almost exclusively used in conjunction with mechanically powered equipment. The benefits of a precision machined swivel bearing still apply: easier swiveling, reduced swivel vibration, and longer trouble free performance. Load ratings are based on manually moved loads at a speed up to 3 mph under ideal operating conditions. Your application will almost never involve ideal operating conditions, which is a good reason to rely on our experienced and knowledgeable staff for a recommendation.