Yoke bearings (bearing cradles) in rack-and-pinion steering gear support the steering shaft opposite the pinion gear, letting the rod maintain precise contact with the pinion gear. The yoke bearings in this case were originally made of powder metal and needed a separately attached insert of steel-backed bronze/PTFE. The costly, multipart design required assembly and had the potential to come apart and jam the steering gear.

The yoke bearings are now molded from PBT polymer, plus 20 to 30% glass fiber. Lifetime lubrication for the steering shaft comes from a 0.0025-in.-thick film bonded to the curved yoke section (wear interface) of the bearing. Wear tests show the bonded film has one-quarter to one-third the wear of the original bearing insert over 200,000 cycles on a simulated steering test rig run at 200 m/sec. The GFTP yoke also withstood the " curbing" simulation of shock loads.

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A powder-metal yoke bearing (right) uses a staked or riveted shoe as a wear surface. The GFTP replacement (left) uses an L26 bonded surface film that prevents glass fibers from abrading the mating shaft and provides lifetime lubrication.

A powder-metal yoke bearing (right) uses a staked or riveted shoe as a wear surface. The GFTP replacement (left) uses an L26 bonded surface film that prevents glass fibers from abrading the mating shaft and provides lifetime lubrication.