The typical marine railway cradle moves on low-friction (1% to 2%) maintenance-free, cast alloy iron rollers. Modern Crandall roller systems are made from steel angle frames with malleable iron bushings welded into accurately drilled or punched holes. Careful fabrication and proper material selection result in greatly reduced roller friction, elimination of roller flange failure, and reduction or elimination of cradle surging. All of these add up to a durable and reliable system which greatly reduces the chance for derailment. A typical Crandall roller frame assembly is shown above and can be custom-designed for your particular railway dry dock installation. Individual Crandall roller system components are described at left and may be purchased separately.