Ex Wilson, NC Truck 1

[GA_Dave]

Rick, it does have the all-steer, I don't believe that we were using it, way to complicated a feature (IMHO) to use for people who have limited training and experience on it.  I believe this truck is still in Wilmington, although not currently being used.

Okay, I feel the need to clear something up.  The above apparatus is equipped with a "self-steering tag axle", not All-Steer, which is a programmable/controllable all-wheel steering system exclusive to Pierce/Oshkosh.  On the above rig, only the second rear axle steers and it is operated by either gravitational/centrifugal forces on the caster angle of the axle or is operated hydraulically in conjunction with the front steering axle.  This system is often seen on large buses and motor homes. This system is always active, there is no turning it off.  With this design, the second rear axle steers the opposite direction of the front axle and the vehicle pivots on the first rear axle.  Vehicles equipped with this feature will typically have dual tires on the first rear axle and a single tire on the second rear axle.

 

On an All-Steer system, all axles are steerable, either in "coordinated" or "crab" mode.  In coordinated mode, both rear axles steer the opposite direction of the front axle, allowing a much tighter turn radius and decreased tire wear.  The cramp angle of the first rear axle is less than that of the second rear axle, which allows smooth turns without dragging the tires.  In crab mode, all axles will steer the same direction, allowing the vehicle to walk to the left or to the right.  All-Steer vehicles have single tires on all axles.