Hyster A1.00XL, Руководство по обслуживанию и ремонту

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2
of current flow is known, use the “Right Hand Rule for
Determining the Direction of Lines of Force Around a
Straight Conductor.” This rule is based on the Current
Theory which assumes that current flows from positive
to negative. To apply the rule imagine grasping the con-
ductor with the right hand so that the thumb extends in
the direction of current flow; then the fingers will point
in the direction in which the lines surround the conduc-
tor.
The lines spread out as expanding circles into space.
The number of lines per unit area is called density. The
density is greatest at the surface of the conductor and
decreases with the distance from the conductor. At a
distance of 25.4 mm (1.0 inch) from the conductor there
is one–half the density of force as at a distance of 12.7
mm (0.5 inch).
If a current–carrying conductor is formed into a single
loop all of the lines around the conductor must pass
through the inside of the loop. The lines on the outside
spread out but the lines on the inside of the loop are
confined and increase the density. This creates a much
greater magnetic effect with the same amount of current
flow.
ELECTROMAGNETS
When two or more loops of wire are wound around a
common core the magnetic field of each turn is affected
by the fields of adjacent turns. The field directly
between adjacent turns of wire is neutralized. The
external and internal lines join to make continuous
loops creating an electromagnet. The internal lines are
concentrated, which creates a strong magnet having a
north and south pole.
The more turns of wire on the coil the stronger the
magnetic field will be. The strength of the magnetic
field also depends upon the amount of current flowing
through the coil.
CURRENT
CARRYING
CONDUCTOR
1/2 INCH
(12.7 mm)
1 INCH
(25.4 mm)
TWICE NUMBER
OF FORCE
LINES PER UNIT
AREA
RIGHT HAND RULE
DIRECTION OF
CURRENT FLOW
MAGNETIC FIELD
6921
FIGURE 2. ELECTROMAGNETIC FIELD