Rigid Bearings have higher axial and radial load capacity due to more cylindrical rollers. The linear contact between the rollers and the raceway ensures that the bearing has a high rigidity. After the installation and coordination are good, the rigidity of the bearing will also increase due to the increase of the preload. The axial offset a of the FAG crossed roller bearing under the action of the axial force Ka through the shaft center can be obtained by the following formula. Axial offset when Ka 2.114 FV: Axial offset when K 2.114 FV: a mm Axial offset between shaft washer and seat washer Ka kN Internal axial force FV kN Bearing preload Cs kN0.926/mm Axial stiffness parameter. The calculation can only give the deflection of the bearing and must also consider the deflection of the surrounding structural members. Sealed bearings are open. Some seals can be designed on the perimeter structure. Lubricated crossed roller bearings can be lubricated with oil or grease. Grease lubrication For grease lubrication, high-quality lithium greases KP2N20 to DIN 51825 are suitable, eg Arcanol MULTITOP. For low speeds, especially horizontal shafts, simple grease lubrication is sufficient. For vertical shaft grease lubrication, install a baffle plate under the SKF bearing to prevent grease leakage. Lithium-based greases with EP additives are recommended. When adding initial grease, add some grease to the gap between the rollers. The amount of regreasing is 20% to 30% of the amount of initial grease. Oil lubrication For oil lubrication, lubricating oils CLP to DIN 51517 or HLP to DIN 51524 viscosity ISO VG 46 to ISO VG 68 are suitable. Circulating oil lubrication In general, the circulating oil of the crossed rollers can be shared with the drive system. If it is only used for bearing lubrication, only a small amount of lubricating oil is required. For high speed, oil cooling is required and a lot of lubricating oil is required, Figure 5. For each operating condition, the final actual required amount of oil is determined by the bearing temperature. V u003d Oil quantity Du003d Bearing outside diameter a u003d Sufficient oil quantity required for lubrication b u003d Oil quantity required for cooling and lubrication Lubrication and Cooling Only for lubrication Figure 5 Oil quantity. Reference Viscosity of Mineral Oil The dynamic viscosity of the lubricant for ensuring adequate lubrication of NTN bearings is determined by the reference viscosity 1 . In this case, ensure that the lubricant operating viscosity (viscosity at operating temperature) is at least equal to the reference viscosity 1. Ratio u003d / 1 u003d 2, Figure 6. The reference viscosity is determined by the average bearing diameter dM u003d (D + d)/2 and the rotational speed. The working viscosity can be inquired by the viscosity/temperature table, the reference temperature and the viscosity at +40 C are required. Lubricants with an operating viscosity greater than 1 at operating temperature have a positive effect on bearing fatigue life. In addition, bearings with EP additives ensure adequate lubrication at low speeds. EP additives are also required at lower levels. Operating temperature Crossed roller bearings are suitable for an operating temperature range of 30°C to +80°C. n u003d working speed1 u003d reference viscosity dM u003d bearing pitch diameter (d +D)/2 u003d working temperature viscosity mm2s1 at +40 C Figure 6 Reference viscosity and V/T for mineral oils.