6. Sealing systems

Their essential roles are to prevent lubricant loss, to prevent undesirable elements from entering them, to evacuate heat due to mechanical losses in the seal, etc., while allowing relative movement between the two rotating shafts to be joined.

Seals (see specialist article in this treatise) are made using – elastic bellows with multiple folds on the one hand, and ligatures on the other – at a modest price compared to the price of the joint itself. Correct installation and use of the right materials directly affect the life of the joint.

Ball joints and tripod joints, whether sliding or not, are greased for life and protected by vulcanized rubber bellows, such as polychloroprenes, with thicknesses of around 2 to 2.5 mm, or increasingly thermoplastics, but with thicknesses of less than 1 mm.

Although these bellows...