Four-wheel Steering Chassis

Model Index

Built: 1989 A non-prototypical emulation of the four-wheel steering system of the contemporary Honda Prelude car.

The rear wheels turned in either the same or the opposite direction to the front ones depending on the degree of lock. Turning the rear wheels in the same direction as the front (at a smaller angle) reduced the effective steering radius but turning them the opposite way increased it.  In the model, this was achieved by connecting the rear radius rod to a free sliding pinion sandwiched between two sliding rack strips. The rack strips were moved by cranks turning at different speeds, so that in a lock-to-lock turn one rack moved from one end of its travel to the other, while the other twice reciprocated from end to end. The cranks were turned by a shaft from the front steering mechanism, geared appropriately.

 

The model also demonstrated power steering. The mechanical power-assister, driven from a PDU, was actuated by a slip clutch on the steering shaft which detected torque applied to it.  Front steering was by rack-and-pinion, with power-assistance acting to both front and rear.

 

The suspension front and rear was by double unequal length wishbones and coil springs, but the model deviated slightly from prototype by having no provision for driving the wheels, all space between them being taken up by the steering mechanisms!                

Rear wheel steering box ▲ 

Builder's comment:  A challenge well met, even if he says so himself.