ON CERTAIN FIRE TRUCKS WITH TANDEM STEER AXLES. THE TRW TIE-ROD ON THE REAR-MOST AXLE OF A TANDEM AXLE IS RESTRAINED FROM ROTATIONAL MOVEMENT BY A PAIR OF ANTI-ROTATION SEALS LOCATED AT THE BALL SOCKET JOINTS. THESE ANTI-ROTATION SEALS WILL COMPRESS OVER TIME. IF THE ANTI-ROTATION SEAL ALLOWS TOO MUCH MOTION, THE SEALS CAN DETERIORATE, ALLOWING CONTACT BETWEEN THE BALL SOCKET AND THE BALL SHAFT. THIS METAL-TO-METAL CONTACT WILL TRANSMIT FORCES INTO THE TIE-ROD TUBE, CAUSING FATIGUE FAILURE INITIATING AT THE ROOT OF THE FEMALE TREADS.