Two different machine types are used with side entry drives. These have bearings on one or two sides. One-sided bearings only occur in smaller machines. The weight of the shaft, as the size increases, causes deflection and bending of the shaft that has to be absorbed by the seal. For this reason, the mechanical seals are equipped with an integrated bearing.

Larger machines have bearings on two sides. Under certain circumstances, however, the weight of the shaft during operation causes bending that has to be tolerated or compensated by the mechanical seal. In addition, on one side, the seal must compensate for changes in the length of the shaft caused by thermal expansion.

These axial movements can be absorbed by scrapers or metal bellows. Bellows can compensate for a misalignment of up to 500 mm (19.69”); scrapers tend to be used for small deflections. 

Paddle-wheel dryers and double conical dryers are typical machines that are equipped with bottom entry drives.

Typical mechanical seals:

Dry running, with contact between the sliding faces:
Gas-lubricated without contact between the sliding faces:
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