*3.3.5 Maintenance free and sealing performance*

Motor bearings are expected to be maintenance free so the grease selection, seal selection plays a major role in bearings performance and life.

#### *3.3.6 Handling acceleration and deceleration during operation*

Electric motors are very responsive to vehicle operating conditions. Motors accelerate as well as decelerate faster compare to ICE. The bearings must be designed to handling this rapid acceleration as well as deceleration. Rolling element separators, raceways geometry should be designed appropriately. Rapid acceleration and deceleration generate sliding motion in the bearing which can lead to damage to bearing raceways or other surfaces. In extreme acceleration and deceleration conditions, may result in catastrophic bearing damage or malfunction of bearing.

#### *3.3.7 Tolerance to electric current leakage*

Present bearings are made up of bearing steel material which is good conductor of electric current. In electric motor current passed though the bearing for any reason is detrimental to bearing function. However, motor feature that can affect conventional steel bearings is the high-frequency voltage switching of the inverter that produces current leakage, particularly at high motor speeds. This current leakage can pass through the bearing and causes, surface damage like surface pitting also called fluting. The initial stage of surface damage generates bearing noise, but the advance stage of surface damage can be catastrophic.

#### **3.4 FEAD bearings**

Front End Accessories Drive (FEAD) system is a combination of multiple subsystem drives in the vehicle for the purpose like air condition compressor drive

#### *Advanced Applications of Hydrogen and Engineering Systems in the Automotive Industry*

or alternator drive etc. The system requires basic requirements like axial and radial loads, static load carrying capacity, dynamic load-carrying capacity, speed, or rpm. However, the FEAD system requirement range beyond basic load-carrying capacities. Modern automobiles are expected to provide more comfort, steering pumps and air conditioner compressors have been added to the FEAD system in addition to alternator or BSG system. Modern automobiles are using comparatively more electronics parts/system operates using electricity which are rising the battery charging capacity. The charging capacity of alternators has increased its size, accordingly, leading to a rise in the amount of torque to be transferred to alternators. The increased torque transfer demands from higher load capacities for the FEAD system bearings.

Below are few technical requirements of FEAD system bearings.
