Four point contact bearings

Four-point bearings belong to the group of single-row angular contact ball bearings and therefore require significantly less installation space in the axial direction than double-row designs. The bearings consist of solid outer rings, split inner rings and ball and cage assemblies with brass or polyamide cages. A large number of balls can be accommodated thanks to the two-part inner rings. The inner ring halves are matched to the respective bearing and must not be mixed up with those of the same size. The outer ring with the ball race and the two inner ring halves can be installed separately from each other. Due to the design of the rolling element raceways with their high raceway shoulders, the contact angle of 35° and the large number of rolling elements, four-point bearings have a very high load-bearing capacity. They absorb high axial forces in both directions and low radial loads. Single-row four-point bearings acting axially on both sides are often combined with a radial bearing and used as an axial bearing with radial play in the housing. Larger four-point bearings therefore have two retaining grooves offset by 180° in the outer ring for fast and secure fixation. These bearings have the suffix N2. The possible misalignment of the inner rings in relation to the outer ring depends on the bearing load, the operating clearance and the bearing size and is very small. Four-point bearings are therefore not suitable for compensating misalignments / angular errors in housing bores or shaft deflections. Misalignment of the bearing rings increases running noise, places greater stress on the cages and has a negative effect on service life. Four-point bearings are not sealed. They are not greased and can be lubricated with grease or oil. Bearings with solid brass cages can be used at operating temperatures from -30 °C to +150 °C. Bearings with outside diameters over 240 mm are dimensionally stable up to +200 °C. Bearings with cages made of glass fiber reinforced polyamide are suitable for operating temperatures up to +120 °C! Four-point bearings with brass cages have the suffix MPA. These window cages are guided on the outer ring. Cages made of glass fiber reinforced polyamide can be identified by the suffix TVP.