Steering rack steering gears are especially suitable for installation in passenger cars and minibuses. Such steering gears as are known from GB No. 20 37 931, for example, have a steering rack that engages with a driving pinion by spring bias on a pressure block. As a result, the steering rack stays meshed with the driving pinion even with imperfections, and no rattling noises occur. The pressure block has the additional function of increasing the steering mechanism's intrinsic friction, as a result of which the axial oscillations of the steering rack and torsional oscillations at the steering wheel can be suppressed. The driving pinion located at the lower end of the steering shaft is supported on both sides by suitable bearings.
In a steering rack steering mechanism with extremely indirect gear ratio, the driving pinion has a relatively small cross section. Therefore, the steering gear does not withstand the torsion and bending forces appearing simultaneously at high steering strains. In the case of strains similar to those in an accident, for example, when bumping over a curbstone at high speed, it is possible that the driving pinion will be broken.
Also, in event of use in a booster power steering system, should the booster power, which normally provides the main force to the rack, fail, then manual force at the steering wheel is used for steering. Such force is through the pinion and causes considerable abnormal stress which can cause bending and breaking.
Therefore, it is the object of the invention to improve the stability under load of a steering rack steering gear by keeping the harmful bending forces acting on the driving pinion as low as possible.