Section 5. Troubleshooting Toyota Orderpicker Model 7BPUE 15 Service Manual
Electric Motor Tests
3.
Y
O
U
should observe the following
Short
-
circuited Armature or
measurements:
Field Winding
Drive Motor
S1
to S2
0.9
to
1.5
1
(shunt)
1
ohms
Motor
S1
to S2
<
1 ohm
A1 to A2
<
1 ohm
Probe Points
A1 to S1; A1 to
>
100,000
1
ohms
1
Resistance
11
A
short rirclriterl winding
is
one in which the
A2
toSl;A2 to
>
100,000
A1 orA2 to
>
100,000
Frame
Lift Motor
<
1 ohm
A to Frame
>
100,000
Steer Motor
A1 or A2 to
>
100,000
Frame
4.
If the meter indicates high resistance in
the armature, check the condition of the
brushes before replacing the motor.
5. If you find an open circuit in a
series
-
wound motor, the motor must be
disassembled by a motor rebuilding facility
to isolate the problem to the field or
armature circuit.
Grounded Motor Test
insulation on the field o; armature has broken
down at two or more points. The breakdown
creates a low resistance path, allowing current
to flow from one turn of the coil to another
adjacent coil turn, without actually flowing
through the coil wire. The result is a decrease in
total resistance of the motor winding and an
increase in the current flow. The severity of the
short circuit depends on its location.
A
shorted motor may be indicated by:
Slow or sluggish operation
Running faster than normal (suggests
a
short in the field)
Overheating
Blowing a power fuse
Burning of brush wires
Severe burning or discoloration on
armature coil
Severe burning or discoloration on one or
two commutator segments every
90"
of
rotation.
These symptoms can be caused by problems
other than the motor itself:
Brake too tight or dragging
Wheel bearings too tight
Faulty transmission
In a grounded motor, an electrical circuit exists
Binding in a related pump, hose, or
between the current
-
carrying conductors and
solenoid valve
the motor housing. This can be caused either by
Load wheels not aligned properly
direct contact or through conductive foreign
Rail guided with drive tire not aligned
material. properly
The ground may be caused by:
Testing a motor for short
-
circuited windings
Insulation breakdown requires special equipment at a motor
Brush leads touching the motor housing
Buildup of carbon dust or other materials
To test for a grounded motor, see
"
Shorts to
Frame Test
"
on page 5
-
4.
00700
-
CL222
-
05,
1
5
March 2005
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