Shock absorber
Suspension strut is a term from the chassis technology of vehicles . It is understood to mean the combination of a spring and a hydraulic shock absorber with the wheel carrier in one unit.
The American engineer Earle S. MacPherson first came up with the idea of combining springs, shock absorbers and wheel carriers . The development was patented in 1949 and built into a series vehicle for the first time in 1950. It is still called the MacPherson strut after its inventor . As early as 1921, however, the Lancia company designed a telescopic strut construction (usually referred to as a telescopic strut axle according to the Lancia patent). In this case, two cylindrical sleeves were attached to the outer ends of a cross member that was firmly screwed to the body, in which a movable cylinder was connected to the wheels via the steering knuckle on each side. A coil spring inside this oil-filled cylinder then absorbed the uneven road surface, while the oil, which was under slight pressure, took over the function of the shock absorber. This system was supported on the body by means of two additional cross struts on each side. This design was first used in the Lancia Lambda introduced in 1922 .
In the case of the strut, the shock absorber is arranged in the center of a coil spring. The spring is compressed by two spring washers located on the piston rod and on the cylinder of the shock absorber. An additional spring made of microcellular polyurethane (MCU), the steel spring and damper work in the same direction of movement, their axes usually coincide. In some vehicles, the spring is set at a slight angle in order to relieve the piston rod of the shock absorber from cornering forces. The progressive spring characteristics of the additional spring ensure a smooth transition with full impact of the chassis forces on the body.
Without springs, the construction is called the damper strut - the suspension is then carried out with a separately arranged helical spring, a transverse leaf spring or a torsion bar on the wishbone .
Some strut designs managed without hydraulics. So -called friction - damped struts were often used on small motorcycles in the GDR , first on the Simson KR50 . They were quite easy to manufacture and repair and were maintenance-free, but did not achieve the same quality of damping effect as hydraulic struts and were therefore later discarded.
Occasionally, spring-damper units, also called spring dampers, are referred to as "struts". They have no effect on the wheel guidance and are often found on rear wheel suspensions. They are cheap to manufacture - especially because of their simple assembly - but they require more installation space than other wheel suspensions.
Use in vehicles
- On motorcycles individually or in pairs on the rear swing arm,
- in the case of historical motorcycles with a front swing arm also in pairs at the front,
- on some current BMW motorcycles also at the front as a Telelever central spring strut,
- in cars on the rear axle or on the front axle, there mostly as MacPherson strut ,
- for bicycles ( mountain bikes ) as rear wheel suspension, occasionally also as front wheel suspension.
Individual evidence
- ↑ The friction-damped struts on the Simson KR 50 . In: Motor Vehicle Technology 6/1962, pp. 239–241.