General Overview of Mercedes automotive Universal Joint Driveshafts
Mercedes driveshafts, with few exceptions, are of the two-piece design. This design of driveline completely eliminates natural frequency vibrations commonly found in many one piece driveshafts.
Mercedes driveline designs since the mid sixties use rubber flex discs to connect the transmission to the driveline and the rear of the driveshaft to the rear axle. These flex discs absorb torsional vibrations from the engine/transmission and reduce shock load to the driveshaft and rear axle. The driveshaft is supported by a ball bearing, encased in a soft rubber cushion. This cushion also dampens unwanted driveshaft vibrations, and to some extent both the flex discs and the support cushion can be "tuned" to the specific arrangement of chassis, transmission and rear axle.
The front half of a Mercedes driveshaft is connected to the rear driveshaft with a universal joint and a sliding spline. A universal joint is a precision bearing, which allows for small angle changes from engine/transmission movement. Mercedes driveshafts use an extremely precise design of universal joint with considerable torque carrying capacity for it's size.
The Mercedes universal joint is quite interesting. Unlike most designs, the roller bearings are contained in a thin shell, stamped from an exotic alloy sheet metal 1 mm thick. It is formed accurately enough to not require subsequent machining and is heat treated sufficiently by the force of the stamping to not require subsequent heat treating. The thinness of this bearing cap allows a large cross and larger roller bearings to be utilized, greatly increasing both strength and bearing life, while keeping size and weight low.
The rear of a Mercedes driveline is much the same as the front and is connected to the rear axle by another flex disc. Mercedes driveshafts also utilize an extremely strong tubular section. It is made from a special steel and cold- worked for additional strength, which saves weight compared to other designs of drivelines. The tubing is inertia, or friction welded, to the ends allowing very fast and accurate manufacturing of Mercedes driveshafts.
Another interesting feature of the most common Mercedes driveshaft design is that the front driveline is centered directly off the transmission main shaft and the rear shaft is centered directly off the pinion shaft. This driveline design causes Mercedes driveshafts to rotate with the smallest amount of radial run-out possible of any design on the market. This design of driveshaft centering is only found at present on Mercedes, Lexus, Alfa and BMW driveshafts.
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