Rack and pinion steering gear for motor vehicle

A motor vehicle rack and pinion steering gear including:

• a housing,
• a rack bar supported on the housing for back and forth linear translation having a rack gear thereon,
• a pinion head rotatably supported on the housing having a pinion gear thereon meshing with the rack gear, and
• a thrust bearing supported on the housing for linear translation perpendicular to the rack bar and slidably engaging the rack bar behind the rack gear opposite the pinion gear,
• characterized in that the rack and pinion steering gear further includes an active lateral thrust control apparatus comprising:
• a spring seat means on the housing,
• a primary spring disposed in compression flexure between the spring seat means and the thrust bearing resiliently biasing the thrust bearing against the rack bar to suppress lateral separation between the rack gear and the pinion gear in a low range of steering torque between the pinion gear and the rack gear,
• a secondary spring bearing against the spring seat, and
• a clutch means operable to engage the secondary spring between spring seat and the thrust bearing in a high range of steering torque between the pinion gear and the rack gear to supplement the bias of the primary spring on the thrust bearing and suppress lateral separation between the rack gear and the pinion gear and to disengage the secondary spring from between spring seat and the thrust bearing in the low range of steering torque between the pinion gear and the rack gear.