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Technical Q&A's

Complete compensation for uneven movement by the Second Joint

Proper connection of two universal joints in series can compensate fully for the unevenness of the movement. For example, tha advance caused by the first joint is compensated by a retard of the same order from the second joint. For this to occur, the following must be fulfilled:



Fig 1.

Two common applications can be derived from this general principle:

1.1 Z - Deflection

In this most common application method, the deflection occurs in one plane only (fig. 2). For complete compensation for movement, the forks of the common shaft must lie in one plane and the deflection angles must be the same.

Fig 2.

1.2 W - Deflection

Here the same applies as for Z-Deflection.

Fig 3.

1.3 Physical Deflection

If the two shaft projections viewed from the side show a Z-Deflection and from the top a W-Deflection or vice versa, there is a physical deflection as shown in fig. 1.

The resulting deflection angles ß1 and ß2 and the twist angle of the deflection planes can be determined from the deflection angles ß1, ß2, ßH1,ßH3 of the projections in figures 4 and 5.

Fig 4.

Example (graphic process)

An arrangement as shown in Fig 6. is used. The size and direction of the twist angle must be determined.

Fig 5.

Fig 6.

Values ßv1 = +15° and ß1H1 = + 7° are entered in the diagram (fig 5) and added geometrically. The dotted line 1 is the deflection plan of the joint 1 viewed from direction C onto the shaft. The length of the dotted line gives the resulting deflection angle ß1 = 16.5°.

The angles ßv2 = -11.5° and ßH2 = + 12° are entered in the same way and an extended line 2 gives the deflection plane of the joint 2. The length of the extended line2 gives the resulting deflection angle ß2.


The resulting deflection angle can be calculated as follows:

and the twist angle:

The sign must be taken from the graphic process. If the twist angle is greater than 90°, in practice the explement angle is taken.

1.4 Permitted Tolerances



1.5 Multiple Joint Shafts

Multiple joint shafts with 3 or more joints are often used in vehicles. Then;

Joints with the same fork position in relation to their deflection plane have the same sign. (See fig 7).
