BALL BEARING - EHL
	Body 1 (ball)	Body 2 (race outer ring)
Young's modulus E	GPa	GPa
Poisson's constant v
Radius rx	10-3 m	10-3 m
Radium ry	10-3 m	10-3 m
Lubricant viscosity η0		Pa·s
Viscosity pressure coeff α		1/GPa
Number of balls z
Rotational speed n		rpm
Bearing load P		N
Effective Young's modulus E'		GPa
Effective contact radius R'		10-3 m
Semi contact radius a		10-3 m
Semi contact radium b		10-3 m
Mean contact pressure pm		GPa
Max contact pressure pmax		GPa
Viscosity number L
Load number N
Film height number H
Couette flow film thickness hc		10-6 m
The lubrication regime in which the bearing operates depends on the rotational speed. At low speed Boundary Lubrication prevails (hc/Ra<1). Representative values for the Ra-value of the ball and raceway are Ra=0.001 and Ra=0.1 μm respectively. It follows that hc>0.2 results in full film lubrication (EHL: hc/Ra>2). This situation can easily be considered by measuring the electric conduction over the inner and outer ring of the bearing (EHL-high electrical resistance, BL-conduction)
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