Vehicle Suspension Systems

Non-independent Front Suspension:

Solid Axle

A solid axle suspension incorporates a solid beam or shaft that spans from left to right in the vehicle. A pivoting connection connects both the left and right ends of the shaft to the wheel spindle, allowing the spindle to turn towards the left of right. The solid axle design may use leaf springs or coil springs connected from the vehicle structure (frame) to the lateral sides of the solid axle beam, therefore allowing upward movement when road bumps are encountered.

Independent Front System Types:

Double Wishbone Design

Double wishbone (and their mechanically equivalent double A-arm design) incorporates a pair of triangular parts or "wishbones", one "wishbone" stacked vertical to the other. The medial (towards the midline of the vehicle) long end of each triangular part is mounted to the structure of the vehicle using a pivoting connection. The lateral (away from vehicle midline) pointed end of each triangular part is mounted to either the upper or lower ball joint of the corresponding wheel hub. The upper and lower ball joints allow the wheel to turn left or right. A spring / shock absorber assembly is typically installed between the vehicle structure and the lateral portion of the lower wishbone (A-arm), thus supporting the vehicle and damping bumps. The double wishbone has been considered the gold standard for rear wheel drive vehicles for many years. A typical double wishbone suspension will use a shorter upper wishbone compared to the lower, thus causing negative camber (tilting out of the lower portion of the wheel) as the suspension arises during bumps or turns. The shorter upper wishbone helps to keep the tire flat during cornering.

McPherson Strut Design

A McPherson strut suspension can be thought of as a variation of the double wishbone design. It borrows the lower wishbone (A-arm) from the double wishbone design. The McPherson strut omits the upper wishbone (A-arm) and instead uses a spring and shock absorber assembly (strut) installed between the lower lateral wishbone (A-arm) and the vehicle structure. This strut is typically much stronger than a typical shock absorber used on the double desirebone design since it must prevent consistent of the lower wishbone (A-arm) which would typically occur during braking or acceleration. The advantages of the McPherson Strut design include simplicity, weight savings and reduced bulkiness. The reduction in bulkiness allows space for a driveshaft to enter the wheel hub, so allowing for use on front wheel drive cars.

Linear Suspension Systems:

Larger aircraft typically use a steerable type of linear suspension system for their nose wheels. This suspension is considered "linear" since the wheel moves in a straight line upwards when a road bump is encountered. These aircraft suspensions can be considered a steerable variation of the oil / air type shock absorbers since both share common characteristics. Although historically a few primitive types of linear suspension systems have been attempted on motor vehicles, none have been very successful then far. Newer designs of linear suspension systems have incorporated electromagnetic motors or remotely mounted springs (connected by cables) for weight suspension and damping.