B - Terms
BACK END OF A MOTOR
The back end of a normal motor is the end which carries the coupling or driving pulley. (NEMA) This is sometimes called the drive end (D.E., pulley end P.E.) etc.
BASE SPEED, RPM
The speed which a DC motor develops at rated armature and field voltage with rated load applied.
BEARINGS
Are used to reduce friction and wear while supporting rotating elements. For a motor it must provide a relatively rigid support for the output shaft.
The bearing acts as the connection point between the rotating and stationary elements of a motor. There are various types such as roller, ball, sleeve (journal), and needle.
The ball bearing is used in virtually all types and sizes of electric motors. It exhibits low friction loss, is suited for high speed operation and is compatible in a wide range of temperatures. There are various types of ball bearings such as open, single shielded or sealed. Reliance Electric offers a unique PLS bearing system.
BEARING LIFE
Rating life, L10 (Bl0), is the life in hours or revolutions in which 90% of the bearings selected will obtain or exceed. Median life (average life), L50(B50)
BRAKES
An external device or accessory that brings a running motor to a standstill and/or holds a load. Can be added to a motor or incorporated.
BRAKING TORQUE
The torque required to bring a motor down to a standstill. The term is also used to describe the torque developed by a motor during dynamic braking conditions.
BREAK AWAY TORQUE
(See Locked rotor torque)
BREAKDOWN TORQUE
The maximum torque a motor will develop at rated voltage without a relatively abrupt drop or loss in speed.
BRUSH
A piece of current conducting material (usually carbon or graphite) which rides directly on the commutator of a commutated motor and conducts current from the power supply to the armature windings.