SPECIFICATIONS

Vehicle Systems Testing And Adjusting
Remove any restrictions in the hydraulic circuit.
Make an inspection of the movable hydraulic
attachments for restrictions. Check for
components that slide, bearing wear, hinges
binding and the correct amount of lubrication on
necessary components.
Problem 3: Sparks at the commutator and/or
rapid brush wear.
Probable Cause:
1. Worn brushes.
Make a replacement of the brushes and make
sure the brushes are seated. See New Brush
installation and Brush Inspection in Testing And
Adjusting.
2. Loose cable connections at the motors terminals
cause a high resistance in the circuit. The
resistance increases amperage draw
(consumption), as a result brushes deteriorate
(destroy), there is arcing on the commutator,
insulation on wires burns and causes a short
circuit to lift truck frame.
Tighten the nuts or bolts that hold the cable
connections on the motor terminals.
3. Overheating (too much heat) of the pump motor.
Check for an overload motor or a motor with
defects. See Armature Commutator Inspection in
Testing And Adjusting.
The duty cycle is too heavy, use the hydraulics
only to the limited capacity of the lift truck.
If the motor has EE covers and the duty cycle is
heavy and within the lift truck capacity, remove
the covers if permitted.
4. Commutator bars burnt in two or more positions at
180¡apart because:
Armature bars open, replace armature.
Short circuit in the armature, see Armature Test.
Armature not in balance which causes brush
bounce, see Specifications.
Motor was stalled against a heavy load and
caused the two bars in contact with the brushes
to burn, see Armature Commutator Inspection.
5. Dirty motor that has metallic or carbon dust. This
dust is a conductor which causes electrical shorts,
increase amp draw and decrease pump motor
output.
Remove any dirt with air pressure.
6. Brushes too tight in brush box. Brush springs not
strong enough to force one or more brushes in
contact with commutator.
a. At installation, pull upon brush leads to make sure
they return to contact with commutator correctly.
See Brush Installation in Testing And Adjusting.
b. If brushes are too tight remove the brush material
with sandpaper until brush movement in brush box
is acceptable.
7. Loose movement of the brushes.
Check the brush springs for cracks and overheat
signs (bluing).
Compare spring force with a new brush spring.
Check the brush holder for oversize (too much
larger than brush size).
Replace the brush spring if necessary.
8. Loose brush leads or motor bus bar connections.
Check the brushes for tight connections. Replace
if leads are loose in brush material
Check all cables and wire connections for tight-
ness.
9. Wrong grade of brushes installed that are not
adaptable to the motor.
Make sure all the brushes are of DAEWOO
standards. Do not use other brands brushes.
10. Replacement brushes are not seated, the current
goes through a small contact area with the
commutator. As a result the brush temperature
increases. Possibly if the contact area is poor the
brushes will be destroyed in a few service meter
hours.
Always seat new brushes when installed, see
New Brush Installation in Testing And Adjusting.
11. Pump motor armature or field windings have a
defect that results in high current draw at low
torque output.
See Armature Tests and Field Coil and Terminal
Tests in Testing And Adjusting.
12. Possible heavy working conditions that cause too
much motor heat and rapid brush wear.
Commutator skin is very black which gives an
indication of high temperatures.
Make a replacement of the brushes and make
sure the brushes are seated. See New Brush
Installation and Brush Inspection in Testing And
Adjusting.
Install extra heavy duty brushes when available.
Check the brush spring for the correct installation
and for the correct spring usage. Too strong a
spring rate will increase amperage draw and
brush wear rate.
Prevent operation in an overload condition
caused by excessive duty cycle which increases
motor temperature and gives rapid brush wear.
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