Daewoo B20S-2 User manual

Specifications
Systems Operation
Testing & Adjusting
Disassembly & Assembly
LiftTrucksPowerTrain
B20S-2, B25S-2, B30S-2
BC20S-2, BC25S-2, BC30S-2
SB2025E01
Aug. 1999

Important Safety Information
Most accidents involving product operation, maintenance and repair are caused by failure to observe basic safety
rules or precautions. An accident can often be avoided by recognizing potentially hazardous situations before an
accident occurs. A person must be alert to potential hazards. This person should also have the necessary train-
ing, skills and tools to perform these functions properly.
Read and understand all safety precautions and warnings before operating or performing lubrication,
maintenance and repair on this product.
Basic safety precautions are listed in the ÒSafetyÓ section of the Service or Technical Manual. Additional safety
precautions are listed in the ÒSafetyÓ section of the owner/operation/maintenance publication.
Specific safety warnings for all these publications are provided in the description of operations where hazards
exist. WARNING labels have also been put on the product to provide instructions and to identify specific hazards.
If these hazard warnings are not heeded, bodily injury or death could occur to you or other persons. Warnings in
this publication and on the product labels are identified by the following symbol.
Improper operation, lubrication, maintenance or repair of this product can be dangerous and could result
in injury or death.
Do not operate or perform any lubrication, maintenance or repair on this product, until you have read
and understood the operation, lubrication, maintenance and repair information.
Operations that may cause product damage are identified by NOTICE labels on the product and in this publica-
tion.
DAEWOO cannot anticipate every possible circumstance that might involve a potential hazard. The warnings in
this publication and on the product are therefore not all inclusive. If a tool, procedure, work method or operating
technique not specifically recommended by DAEWOO is used, you must satisfy yourself that it is safe for you
and others. You should also ensure that the product will not be damaged or made unsafe by the operation, lubri-
cation, maintenance or repair procedures you choose.
The information, specifications, and illustrations in this publication are on the basis of information available at the
time it was written. The specifications, torques, pressures, measurements, adjustments, illustrations, and other
items can change at any time. These changes can affect the service given to the product. Obtain the complete
and most current information before starting any job. DAEWOO dealers have the most current information avail-
able.
WARNING
1

Power Train Index
Index
Systems Operation
Drive Motor............................................................... 6
Final Drive ................................................................ 8
General Information.................................................. 5
Power Transfer Group.............................................. 7
Testing And Adjusting
Drive Motor..............................................................14
Armature Terminal Test ......................................19
Armature Tests ...................................................15
Brush Holder Test ..............................................19
Brush Life Estimate............................................20
Commutator Inspection......................................17
Field Coil And Terminal Tests.............................18
Motor Brushes....................................................14
Thermal Switch Tests.........................................20
Final Drive ...............................................................27
Wheel Bearing Adjustment.................................27
Power Transfer Group Adjustments ........................21
Pinion Bearing Adjustment.................................24
Pinion Depth Check ...........................................24
Pinion Installation...............................................22
Power Transfer Group........................................21
Power Transfer Group Bearing And Gear
Clearance (Backlash) Adjustments...............25
Troubleshooting........................................................ 9
Checks During Operation ................................... 9
Drive Motor .................................................... 9
Power Transfer Group And Final Drive ........13
Visual Checks ..................................................... 9
Specifications
Drive Axle Mounting Group .....................................33
Drive Motor..............................................................30
Drive Tire Installation...............................................33
Final Drive ...............................................................32
General Tightening Torque ......................................28
Power Transfer Group .............................................31
Disassembly & Assembly
Brakes, Brake Adjuster And Wheel Cylinder...........36
Final Drives And Hubs.............................................45
Oil Cooled Disc Type Brake ....................................48
Power Transfer Group .............................................39
3

Power Train Systems Operation
Systems Operation
General Information
Power Flow
(1) Final drive (2) Power transfer group (3) Drive motor
5
The power train for the B, BC MODEL Lift Trucks
consists of three main components: drive motor (3),
power transfer group (2) and final drive (1).
Electric storage batteries are used as a power source
for drive motor (3). The drive motor turns power
transfer group (2). The power is sent through the
power transfer group to the axles. The axle turns final
drive (1), which is part of the drive wheels.

Power Train Systems Operation6
Drive Motor
Drive Motor
(1) Shaft. (2) Cover. (3) Thermal switch (thermostat). (4) Commutator. (5) Armature assembly. (6) Field coils. (7) Frame.
(8) Brush holder.
1
32
4
8765
The drive system is operated by a direct current (DC)
motor. Electric storage batteries are the source of
power for the DC motor.
The drive motor is a series wound motor and uses a
high temperature insulation. A series wound motor is
a commutator motor. The field and armature circuits
are a series, which provides a single path for the cur-
rent. Armature (5) is mounted with single row ball
bearings at each end. The ball bearings are perma-
nently lubricated with a high temperature lubricant.
The electrical connections to the motor are made at
corrosion resistant terminals on motor frame (7). On
the outside of the motor frame is cover (2) that can
be removed for easy access to the brushes and the
commutator. Field coils (6) are fastened to the inside
of the motor frame.
The four motor brushes are held in four brush hold-
ers (8). A spring holds each of the brushes against
commutator (4) as the brushes wear.
The Optional Superior (S) function equipped lift
truckÕs drive motor is protected from overheating by a
thermal switch (thermostat) (3). The thermal switch
opens at 150 L6¡C (302 L11¡F). It closes at 130 L7¡C
(266 L13¡F). When the normally closed thermal
switch is open, the amount of current through the
motor is limited to allow the motor to cool. The motor
has a fan for cooling.
The drive motor is activated when the parking brake
is released, the key and seat switch are closed, a
direction is selected and the accelerator pedal is
depressed.
The drive motor powers the power transfer group
through shaft (1).

Power Train Systems Operation7
Power Transfer Group
Power Transfer Group
(1) Bevel gear (2) Differential case (3) Helical gear (4) Spiral hypoid pinion (5) Input Gear (6) Drive Motor Shaft
1
23
5
6
4
The power transfer group is mounted under the
frame in the front of the lift truck. ItÕs a double reduc-
tion unit with the final reduction through spiral hypoid
pinion (4) and bevel gear (1).
Power for the transfer group comes from the electric
drive motor through the input gear connected with
the Drive Motor Shaft (6) through the spline . The
input gear (5) turns helical gear (3) that is mounted
on the shaft of the hypoid pinion (4).
The hypoid pinion is engaged with bevel gear (1)
which is mounted to differential case (2).
Differential case (2) has two pinion gears that are
engaged with two side gears. The side gears turn the
axle shafts.
The power transfer group is used to send the power
from the electric drive motor to the wheels. When
one wheel turns slower than the other, the power
transfer group lets the inside wheel stop or turn slow-
er in relation to the outside wheel.
When the truck is moving straight in a forward direc-
tion with the same traction under each wheel, there is
equal torque on each axle. This holds (stops) differ-
ential pinion gears which give the same effect as if
both wheels were on the same axle. During a turn,
the force (traction) that is on the drive wheels is dif-
ferent. These different forces are also felt on opposite
sides of the power transfer group and cause differen-
tial pinion gears to turn. The rotation of differential
pinion gears stops or slows the inside wheel and lets
the outside wheel go faster. This moves the machine
through a turn under full power.
The power transfer group gets lubrication from oil
thrown about inside the housing, by the rotating
gears.

Power Train Systems Operation8
Final Drive
Final Drive
(1) Axle shaft (2) Hub (3) Drive wheel (4) spindle
The power transfer group turns axle shaft (1). The
gear teeth on the end of axle shaft (1) engage the
gear teeth of hub (2). The gear teeth of hub (2) are
on the inside diameter of the hub, which causes the
rotation of the hub to be the same as the axle shafts.
The reduction in size between the axle shaft and the
hub causes the hub to turn at a slower speed.
Spindle (4) is fastened to the truck frame and is used
as a support for hub (2).
Drive wheel (3) is fastened to hub (2) and turns with
the hub.
The final drive is a grease lubricated unit.

Power Train Testing And Adjusting
Troubleshooting
Visual Checks
Make a visual inspection of the truck to check for
problems. Operate the truck in each direction.
Make a note of the noises that are not normal and
find their source. If the operation is not correct, make
reference to the Check List During Operation for
ÒProblemsÓ and ÒProbable CausesÓ.
Checks During Operation
Drive Motor
Before an analysis is made of any electric drive
motor problem, always make reference to the
Troubleshooting section of the MicroController
System Operation module.
The lift truck can move suddenly. Battery voltage
and high amperage are present. Injury to
personnel or damage to the lift truck is possible.
Safely lift both drive wheels off the floor. Put wood
blocks or jack stands of the correct capacity under
the frame so the drive wheels are free to turn.
During any test or operation check, keep away
from the drive wheels. The head capacitor (HEAD
CAP) will have to be discharged before any
contact with the control panel is made. Disconnect
the battery and discharge the HEAD CAP. Rings,
watches and other metallic objects should be
removed from hands and arms when
troubleshooting the MicroController control
system.
To prevent personal injury, never use air pressure
that is more than 205 kPa (30 psi), and wear
protective clothing and a face shield.
NOTICE
To prevent damage to electrical components, make
sure the air line is equipped with a water filter when
they are cleaned with air.
If an electrical failure or an overload of the motor
is present, personnel must not breathe the toxic
fumes which are a product of the burnt insulation.
All power must be disconnected from the motor
before any inspection is made to find the failure.
The area around the motor must be well ventilated
(air flow) and the motor is to be cooled before any
repair work is done. Water must not be used on
any electric equipment because of the danger of
electrical shock. If fire is present, disconnect the
electrical power and use a carbon dioxide
extinguisher to put the flame out.
Do not operate the drive motors without a load,
as too much speed may cause damage to the
motor and injury to personnel.
Problem 1: Drive Motor Will Not Operate.
Probable Cause:
1. Switch not closed (battery connector, key switch,
seat switch, direction switch or parking brake
switch):
Close the switch. If it still does not operate, test
for power to the control panel and power flow
through each switch with a voltmeter.
2. Bad connection. Fuse bad:
Check battery connections. Check connections
at battery connector. Check fuses, drive and
logics.
Replace fuse if bad.
Check the Drive motor and control panel for
possible reasons for a bad fuse. Some causes
are:
a. Operate during too heavy transistor load, too
high current limit (C/L).
b. Operate in stall conditions.
c. Possible short circuit in drive motor, see
Probable Causes 5, 6 and 7.
3. Low battery voltage:
Check battery terminal voltage. If too low,
charge the battery.
Check all the cells for one or more that have
defects.
Check the specific gravity of each cell. The
maximum density difference from the highest to
the lowest cell must not be more than. 020 SG
(specific gravity).
WARNING
WARNING
9

Power Train Testing And Adjusting
4. Control panel operation not correct:
See the MicroController System Operation
module.
5. Brushes are worn:
Inspect the drive motor commutator for burnt
marks or scoring (scratches). Make corrections
or make a repair of the armature commutator
and replace the brushes as necessary.
See Armature Commutator Inspection and
Brush Inspection in Testing And Adjusting.
Make reference to Problem: Sparks At The
Commutator And/Or Rapid Brush Wear.
6. Check for opens in the field coils:
Test coils according to procedures in Testing
And Adjusting. If there are opens, make a
replacement of the field assembly.
7. Check for a short circuit in the armature windings:
Loose field winding pole pieces, make the
necessary corrections.
Field armature bar insulation.
Repair or rebuild the insulation or make a
replacement of the armature.
8. Static return to off circuit actuated:
If the static return to off is actuated, the control
will not start again until the accelerator is
released and the directional control lever is
returned to neutral.
Problem 2: Traction will not operate through a
normal work period, but hydraulic operation is
normal.
Probable Cause:
1. Brakes have a defect, cause a resistance (lack of
free movement). Heat increases, which causes the
motor to stall:
Check the brake adjustment according to the
procedures in Testing And Adjusting in the
Vehicle Systems module.
2. Too much heat in MicroController control panel
because:
a. Extra heavy traction loads.
Decrease the duty cycle load.
b. Faulty thermal switch.
See the MicroController System Operation
module.
c. Too high current limit (C/L) setting.
Lower the setting on the C/L adjustments.
These can cause transistors to become defective,
control panel failure or drive fuse to go bad.
Problem 3: Neither traction or hydraulic will last
through a complete normal work period.
Probable Cause:
1. Too small a battery equipped in the lift truck:
Use a larger battery for the complete work cycle
and normal work period.
2. Battery not being fully charged or equalized during
the battery charging operation:
Check the battery cells for an equalization
charge (a charge to make the specific gravity
the same in all cells). Check the battery charger
for defects.
3. Battery change interval is too long or changed
battery cooling time is too short. This decreases
the capacity and the ability of the battery:
Decrease the battery work duration before a
change. Increase the battery cooling time after
a charge before it is put to use.
4. Battery has one or more defective cells which
results in less than the rated capacity and ability of
the battery:
Replace the battery.
5. Traction system draws (make a consumption of)
too much battery power because of traction
system faults. Operation of the duty cycle
(complete working cycle) condition is not correct:
Check the brake adjustment according to the
procedures in Testing And Adjusting in the
Vehicle Systems module, Check the mechanical
components such as wheel bearings, axles,
etc., for corrections to eliminate the faults.
Change to a tire with less friction.
6. Hydraulic system draws too much battery power
because of lifting and tilting arrangements, or
hydraulic conditions are not correct for the duty
cycle:
Decrease hydraulic relief valve setting to the
capacity that only will be used.
Change to a smaller hydraulic pump.
Check the mast for restriction during operation.
7. Lift truck working more than the capacity of its
design with no available power after one work
shift:
Have available an extra (exchange) battery.
Decrease the speed and work load required to
complete the work shift.
10

Power Train Testing And Adjusting
Problem 4: Sparks at the commutator and/or
rapid brush wear.
Probable Cause:
1. Worn brushes:
Make a replacement of the brushes. See New
Brush Installation And Brush Inspection in
Testing And Adjusting.
2. Overheating (too much heat) of the traction motor:
Check for an overload motor or a motor with
defects. See Armature Commutator Inspection
in Testing And Adjusting.
Decrease the current limit (C/L) adjustments if
set too high. See the MicroController System
Operation module.
Test the plugging rate, if set too short it will
cause arcing and wear at the brushes.
The duty cycle is too heavy, change the duty
cycle.
3. Defective drive motor:
See Armature Commutator Inspection in Testing
And Adjusting.
a. Commutator bars burnt in two or more positions at
180¡ apart because:
(1) Armature bars open.
Make a replacement of the armature.
(2) Motor was stalled against a heavy load while
power discharged and caused the two bars, in
contact with the brushes, to burn.
NOTICE
Too heavy a load can stall the motor, and result in a
failure to the drive motor.
(3) Short circuit in the armature.
See Armature Tests in Testing And Adjusting.
(4) Armature not in balance, out of round, off center
or with high commutator bars. This causes the
brushes to bounce (move up and down).
Make sure the diameter is the same all the way
around and is in center line with the shaft. See
Specifications.
b. Dirty motor that has a metallic or carbon dust. this
dust is a conductor which causes electrical shorts,
increase amp draw and decrease drive motor
output:
Remove any dirt with air pressure.
c. Brush movement causes arcing and brush wear:
Check the brush springs for cracks, and
overheat signs (blue).
Compare spring force with a new brush spring.
Check the brush holder for oversize (larger size
than for brush).
Replace the brush spring if necessary.
d. Loose brush leads or motor bus bar connections.
Loose cable connections at motor terminals.
Results are:
(1) High resistance and heating.
(2) Faster brush wear.
Check brushes for tight-connections.
Replace the brushes if leads are loose in
brush material. Check all cable and wire
connections for tightness.
e. 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 of brushes.
f. Possibly heavy working condition that causes too
much motor heat and rapid brush wear:
Make a replacement of the brushes and make
sure the brushes are seated. See New Brush
Installation and Brush Inspection in Testing And
Adjusting.
Check the brush springs 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 stall condition. Excessive
(too much) duty cycle which increases motor
temperatures and rapid brush wear.
4. Overload of the drive motor such as: towing loads,
constant ramp operation, chiseling (hydraulic
actions that are not practical) loads and dragging
(pull or push loads on the ground) loads:
Operator training for better working practices.
Add an auxiliary cooling to the drive motors.
5. Current limit (C/L) set too high that causes too
much current consumption through motors in the
transistor range:
Decrease the current limit (C/L) adjustment to
the correct setting, see the MicroController
System Operation module.
6. Drive 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.
11

Power Train Testing And Adjusting
7. Restriction caused by components:
Correct and make adjustments to wheel brakes
and parking brakes that drag.
Make changes to tires with less restriction.
Check and correct wheel bearing torques.
Problem 5: Low resistance to ground [battery
polarity either positive (+) or negative (-) or a
medium voltage is in direct contact with truck
frame (body) or drive motor body].
Probable Cause:
1. Dirty battery, electrolyte on top of cells and is in
contact with the frame. Current flows through
battery box, which places a voltage on the truck
frame:
Clean the battery with baking soda and water
solution.
2. Battery or control panel wire connections in
contact with truck frame:
Make a continuity test and move the wire from
contact.
Remove wires in sequence until the fault is
cleared.
The fault will be in the wire last disconnected.
3. Dirty motor:
Remove metallic or carbon dust with air
pressure.
4. Wet motor:
To dry the motor, heat it to 90¡C (194¡F).
Problem: 6. Commutator surface has groove or
extra wear.
Probable Cause:
1. Brushes are worn too low, brush wires caused
arcing on the commutator:
Replace the brushes. See Brush Inspection in
Testing And Adjusting and the method to make
the Brush Lift Estimate in Testing And Adjusting.
2. Dirty motor; and possibly salt water got inside:
Disassemble motor, remove the debris with air
pressure. If necessary, dry the motor with heat
to 90¡C (194¡F)
3. Grades of brushes mixed:
Make sure all the brushes are of DAEWOO
standards. Do not use other brands of brushes.
Problem 7: Lift truck moves faster in one
direction than the other direction with the same
amount of accelerator pedal movement in Bypass
mode (speed).
Probable Cause:
1. Motor brushes not located in the correct electrical
position (brush neutral settings):
If the holes in the brush holder are not
extended, make them longer so that brush
holder can have a little rotation. When the
holder is in the correct position, lift truck speed
will be the same in both directions.
2. One directional contactor worn more than the
other or loose connection on one contactor:
Check contactor for wear and tighten any loose
connections.
Problem 8: Lift truck will not get to top speed.
Probable Cause:
1. Battery not fully charged or battery has bad cells:
Charge the battery. Check for bad cells.
Replace battery if necessary.
2. A fault either in the drive motor, control panel or
drive train:
Check lift truck speed in both directions. If the
MicroController panel needs tuned up, make
adjustments as shown in the respective
MicroController System Operation module. If
the drive motor is at fault, make the tests of the
motor components in Testing And Adjusting.
Problem 9: Lift truck does not have enough
power to position itself under a load. Lift truck
does not have enough power on ramps or towing
trailers.
Probable Cause:
1. Current limit (C/L) set too low:
Set current limit (C/L) to specification in the
MicroController System Operation module.
12

Power Train Testing And Adjusting
2. Current limit (C/L) circuit has a defect:
Make test to the MicroController control panel as
stated in the respective service module. Repair or
replace components as necessary.
3. Unpolished or improperly positioned forks:
Install tapered and polished forks. Position forks
correctly for load being lifted.
4. Lift truck equipped with tires that have poor
traction:
Install tires that have good traction per
recommendation from DAEWOO Inc.
5. Lift truck work load is too heavy or the duty cycle
too long:
Decrease the work load and/or duty cycle.
Problem 10: Lift truck has slow acceleration:
Probable Cause:
1. Drive control overheated and the thermal switch
opens:
NOTE: The lift truck will still go into the bypass
mode, but current limit will be cut back in the
transistor mode if the thermal switch opens.
Allow the MicroController control panel to become
cool so the thermal switch will close.
NOTE: The thermal switch will open circuit if the
temperature is 150 L6¡C (302 L11¡F) and reclose
(short circuit) at 130 L7¡C (266 L13¡F).
Power Transfer Group and Final Drive
Problem 1: Constant noise in drive axle housing.
Probable Cause:
1. Lubricant not to the specified level.
2. Wrong type of lubricant.
3. Wheel bearings out of adjustment or have a defect.
4. Bevel gear and pinion not in adjustment for correct
tooth contact.
5. Teeth of bevel gear and pinion have damage or
wear.
6. Too much or too little pinion to bevel gear
clearance (backlash).
7. Loose or worn drive motor bearings.
8. Loose or worn side bearings.
9. Noise in the drive wheel reduction components.
Problem 2: Noise at different intervals.
Probable Cause:
1. Bevel gear does not run evenly.
a. Nut on drive gear not tightened correctly.
b. Drive gears have a defect (warped).
2. Loose or broken bearings.
3. Failure of or not enough lubricant on the drive
wheel reduction components.
Problem 3: One drive wheel does not turn (motor
operates).
Probable Cause:
1. Broken axle shaft.
a. Loose wheel bearings.
b. Loose flange studs or nuts.
c. Bent housing.
2. Pinion gear teeth have damage.
3. Bevel gear, pinion or gears broken.
Problem 4: Leakage of lubricant.
Probable Cause:
1. Loss through axle shafts.
a. Lubricant above specified level.
b. Wrong kind of lubricant.
c. Restriction of axle housing breather.
d. Axle shaft oil seal installed wrong or has
damage.
2. Loss at pinion.
a. Lubricant above specified level.
b. Wrong kind of lubricant.
c. Restriction of axle housing breather.
d. Drive motor seal worn or not installed correctly.
13

Power Train Testing And Adjusting
Drive Motor
Motor Brushes
Brush Inspection
1. Measure the brush material on the longest side.
Brush Measurement
2. If the brush length is less than 19 mm (.75 in) on
the longest side, replace the brushes.
New Brush Installation
NOTE : Installation of new brushes is a two person
operation.
1. Disconnect the batteries and remove them from
the lift truck. Put the batteries close enough to the
truck that the battery connector can be plugged in.
2. Lift the truck and put blocks under it so that the
drive wheels are off the ground. Put blocks in front
and in back of the steering wheels.
3. Discharge the head capacitor.
4. Remove the commutator screen cover remove old
brushes.
Install Brushes
(1) Brushes.
NOTICE
Installation of the wrong brushes can cause early
motor failure. Always make sure the correct DAEWOO
brushes are installed.
5. Install new brushes(1). Make sure the brushes
move freely in the brush holders. Use a piece of
plain bond paper to remove brush material if there
is a restriction of brush movement.
Install Springs
(2) Spring.
6. Place carefully the brush spring(2) on the top of
brush and make sure they fasten into the brush
holder box.
7. Pull up on the two wires of each brush until the
contact end of the brush moves away from the
commutator. Release the wires to see if the brush
moves smoothly back into contact with the
commutator. If it is too difficult to pull out, or it does
not move smoothly in the brush holder box,
remove the spring and brush. Make an inspection
to find and correct the cause of the problem.
8. Connect the batteries to the battery connector.
14
1
2

Power Train Testing And Adjusting
Wear eye protection when seating, polishing or
cleaning the motor with air pressure. During the
seating and polishing procedure, keep fingers
away from components in rotation. For prevention
of injury to fingers, do not use a commutator
cleaner or brush seater stone that is shorter than
63.5 mm (2.50 in.).
Brush Seating
(3) ZLX Ð0036 Brush seater stone.
9. Put ZLXÐ0036 Brush Seater Stone (3) on the
commutator and operate the motor at a slow
speed.
NOTICE
Do not let stone (3) stay in contact with the commutator
bar too long. This causes more wear than is necessary
to the brushes and the commutator.
10. Move stone (3) across the commutator at the
backe edge of the brushes for a short time. This
will take the shiny finish off the commutator and
seat the new brushes.
11. Turn the key switch to the OFF position and
disconnect the batteries. Check the contact
surface of each brush. At least 85% of the brush
contact surface of each brush must show wear. If
necessary, do Steps 8 through 11 again until the
correct wear can be seen on the brush contact
surface.
NOTICE
Never use air pressure that is more than 205 kPa (30
psi). Make sure the line is equipped with a water filter.
12. After the brushes have the correct seat contact
surface, operate the motor at slow speed. Use
compressed (pressure) air to remove all dust and
abrasive grit.
Armature Tests
Test For Short Circuit
Short Circuit Test
(1) Growler. (2) Armature. (3) Hacksaw blade.
(4) Green light. (5) Red light.
1. Put armature windings (2) in the jaws of growler.
(3).
2. Turn the growler (1) on. Slowly turn the growler on
the armature (2) while a hacksaw blade (3) is held
over the windings.
3. If the windings are shorted, the green light (4) will
be on. The red light (5) will be on if the windings
do not have a short.
The odor of burned insulation from the drive motor
while it is in operation is an indication of a short in
the armature.
Tools Needed
Digital Multimeter Or Equivalent 1
Growler Tester 1
WARNING
15
3
5
3
2
4
1

Power Train Testing And Adjusting
Ground Test
Ground Test.
A digital multimeter can also be used to test for
grounds. Put the Function/Range Switch on the 2M
resistance (½) scale. When the test probes are put
on the commutator and the shaft, the meter must
give an indication of over load (OL). This means that
the resistance is more than 2 megohms.
NOTICE
Never use air pressure that is more than 205 kPa (30
psi). Make sure the air line has a water filter.
If there is an indication of a ground in the above test,
remove any dirt or debris form the armature with
compressed (pressure) air.
Do the test for grounds again. If there is still an
indication of a ground, make a replacement of the
armature.
Open Circuit Test
Open Circuit Test
1. Put the digital multimeter Function / Range Switch
on the 200 ohm resistance (½) scale.
2. Put one test lead on one commutator bar. Put the
other test lead on an adjacent (next to) bar and
there must be less than one ohm resistance.
This test can also be done with an instrument,
such as a Kelvin Double Bridge, that can make a
measurement of very low resistance. Do the test
the same as above and make a comparison of the
resistance measurements.
Two burned areas on opposite sides of the
commutator are indications of an open armature
winding. These burned areas can cause very rapid
brush wear.
16

Power Train Testing And Adjusting
Commutator Inspection
Surfaces of Commutators that need Replacement
Marks on the Commutator Surface
Marks on the commutator surface are an indication
that metal has moved from the commutator surface
to the carbon brushes. Marks will cause fast brush
wear.
Threads on the Commutator Surface
Threads (grooves that look like threads) on the
commutator surface, will also cause fast brush wear.
Grooves on the Commutator Surface
Grooves on the commutators surface are caused by
a cutting material in the brush or atmosphere.
Copper Drag on the Commutator Surface
Copper drag is an extra amount of commutator
material at the back edge of the commutator bars.
17
EHPS009B
EHPS010B
EHPS012B
EHPS011B

Power Train Testing And Adjusting
Pitch BarÐMarks on the Commutator Surface
Pitch barÐmarks cause low or burnt marks on the
commutator surface.
Field Coil and Terminal Tests
Open Circuit Test
Open Circuit Test
1. Put the digital multimeter Function/Range Switch
on the 200 ohm resistance (½) scale.
2. Put one test probe to each outer field terminal
(S1,S2).
3. The resistance must be less than one ohm. If the
resistance is too high, it is an indication of
corrosion on the terminals or an open field coil.
Ground Test
Ground Test
(1) Field Terminal. (2) Motor housing.
1. Put the digital multimeter Function/Range Switch
on the 20M resistance (½) scale.
2. Put one test lead to either outer field terminal (1)
and the other test lead to the motor housing (2).
There must be more than one megohm resistance.
3. If there is a measurement of less than one
megohm, it can be caused by wet insulation on the
field windings or excessive brush dust in housing.
Heat the motor at 88°C (190°F) until the resistance
goes above one megohm. If the resistance does
not go above one megohm, the shell and field
assembly must be replaced.
Tools Needed
Digital Multimeter Or Equivalent 1
18
EHPS013B
1
2

Power Train Testing And Adjusting
Armature Terminal Test
Test for Continuity
Brush Test
1. Put the digital multimeter Function/Range Switch
on the 200 ohm resistance (½) scale.
2. Put one test lead to an outer armature terminal
and the other test lead to each brush lead that
connects to that terminal. There must be less than
one ohm resistance.
3. Do Step 2 again with the other outer armature
terminal and brush leads.
4. Too much resistance is an indication of corrosion
at the connection to the terminal.
Ground Test
Ground Test
(1) Armature Terminal. (2) Motor Housing.
1. Put the digital multimeter Function/Range Switch
on the 20M resistance (½) scale.
2. Put one test lead to an outer brush terminal (1)
and the other test lead to the motor housing (2).
There must be more than one megohm resistance.
3. Do the test again with one test lead on the other
outer brush terminal.
Brush Holder Test
Brush Holder Test
(1) Brush Holder. (2) End Bell.
1. The brush holders are mounted on the rocker at
the commutator end of the motor. Make a visual
inspection of the brush holders and the rocker.
2. Put digital multimeter Function/Range Switch on
the 200 ohm resistance (½) scale. Put one test
lead to a brush holder (1) and the other test lead
to the end bell (2). The meter must show overload
(OL).
3. Check each brush holder. If meter reading is low,
the brush holder is grounded. Replace the rocker.
Tools Needed
Digital Multimeter Or Equivalent 1
Tools Needed
Digital Multimeter Or Equivalent 1
19
2
1
2
1