420

Front 1

Armature Reaction

Back 1

The magnetic field produced by current flowing through the armature coils in a motor or generator

Front 2

Babbitt

Back 2

An anti-friction alloy of tin, copper and antimony used for bearings and socketing of wire ropes for elevators. Several combinations of the base metals are available.

Front 3

Ball Bearings

Back 3

A bearing in which a shaft bears on small spherical metal balls that turn freely as the shaft revolves.

Front 4

Bronze

Back 4

Alloy bearing material consisting of copper,tin,lead,and zinc. It has excellent anti-friction qualities, strength, hardness, ductility and machinability.

Front 5

Coil pitch

Back 5

The number of armature slots between sides of one armature coil which determines the size of the preformed armature windings.

Front 6

Eddy Currents

Back 6

Waste current induced in the core material of armatures and field pieces, dissipated as heat

Front 7

End Bells

Back 7

Housings fastened to the frame of a generator or motor that enclose, support and protect the bearings. One bell holds the commutator brush rigging in a DC motor or DC generator

Front 8

Field

Back 8

The portion of space near a field magnet in which magnetic lines of force exist.

Front 9

Field windings

Back 9

Insulated wire wound around a laminated iron core to produce an electro-magnetic field in motors and generators

Front 10

Flux

Back 10

The field of magnetic force surrounding a current-carrying conductor, electromagnet or permanent magnet.

Front 11

Frame

Back 11

(1) foundation of a machine that supports other machine components in proper relationship to each other. (2) the safety plank or bolster, Stiles and crosshead assembly of an elevator car installation. (3) the lintel or header, and sill assembly of an elevator hoistway entrance.

Front 12

Hysteresis Losses

Back 12

(1) the tendency of a substance to resist changes in its magnetization. (2) the lag in effect on a substance of a changing magnetizing force.

Front 13

Interpoles

Back 13

Wire-wound iron cores used in DC electric motors and generators to stabilize the neutral or commutating plane.

Front 14

Laminations

Back 14

A relatively thin member, usually made of sheet material. A complete structure is made by assembling the laminatations in the required number of layers. In a core that carries alternating magnetic flux, the core material is usually laminated to reduce eddy-current losses.

Front 15

Lap Windings

Back 15

An armature winding which has the beginning and end leads of each coil connected to adjacent commutator bars.

Front 16

Mica

Back 16

Thin compressed sheets of crystallized heat resistant mineral having excellent insulation qualities.

Front 17

Neutral Plane

Back 17

The point at which brushes are placed on a DC motor generator so they will short circuit a coil on the armature winding when it is cutting the least number of magnetic lines of force from the field poles, i.e, approximately midway between the poles.

Front 18

Pole Pieces

Back 18

The iron or steel structure on which the coil or coils are placed to form a magnetic pole of a motor or generator. They are actually laminated to reduce hysteresis power losses. No couls are needed for the permanent magnet-type pole pieces.

Front 19

Series

Back 19

An electrical circuit in which the various components are connected end-to-end across a power source. In a series circuit, current flow is the same direction and magnitude in all parts of the circuit.

Front 20

Shunt

Back 20

(1) a parallel connection. (2) a resistive element placed across the terminals of an armature to by-pass a portion of current. (3) a flexible electrical conductor designed to conduct current around the mechanical joint between two conductors. (4) the resistive element (usually of very low resistance) used in parallel with a DC ammeter movement to bypass a calibrated portion of the total circuit current.

Front 21

Sleeve Bearings

Back 21

A bearing in the shape of a stationary tube around a shaft which allows the shaft to revolve in the tube. The tube is usually made of brass or babbitt.

Front 22

Slinger

Back 22

A chain or ring device that is located on an armature shaft of a machine that carries oil for lubricating sleeve bearings.

Front 23

Wave Windings

Back 23

An armature winding which has the beginning and end windings of a coil connecting a definite number of commutator bars apart, depending on the number of field poles and the number of bars on the commutator.

Front 24

Yoke

Back 24

(1) Foundation of a DC machine that supports other machine components in proper relationship to each other. Commonly referred to as a frame. (2) the part of an electric motor or generator which holds the brush holders in correct relationship with each other as they as a group are shifted in relation to the neutral plane.

Front 25

Commutator

Back 25

The device which performs the process of communication. It consists of a number of segments usually made of copper or copper alloy, individually insulated from each other and from the supporting structure. The segments are assembled in the form of a ring and each is connected to one or more armature coils in a manner depending on the design of the armature winding. The outer surface is exposed for contact with brushes which collect the current in a generator and distribute the current in a motor.