The Design of Rolling Bearing Mountings

39 Shock absorbing strut for the front axle of a carFront axles are being equipped more and more frequentlywith McPherson shock absorbing struts.When driving, the coil spring and the damping unit ofthe McPherson strut cause movements relative to thebody which are due to spring deflection and the degreeof lock. For comfort reasons and for easy handling,these slewing motions are supported either by rollingbearings or rubber elements. Deep groove ball bearingsbest meet all requirements.Bearing selectionRequirements– Accommodation of weights and high shock loads– Maintenance-free designVariants– Damping unit and spring coil rotate together –single path solution (fig. a). The spring coil loadsand the pulsating loads from the piston rod act onthe strut bearing.Possible bearing designs: Deep groove ball bearingsloaded axially (with cage or full-complement variantswith a fracture-split outer ring) or thrust ballbearings.– Movements of the shock absorber's piston rod andof coil spring are independent of each other – dualpath solution (fig. b).Direct connection of shock absorber's piston rod tothe body via a rubber element; coil spring supportedby a special thrust ball bearing or angular contactball bearing (spring seat bearing).Both variants meet all requirements concerning sealing,for-life lubrication and economic efficiency.ab39: Shock absorbing strut for the front axle of a car; a: single path solution; b: dual path solution59 FAG