starter motor bench testing and repair

TTEC 4841 - Electrical and Electronics- Practical

12/8/2011 friday

start = 1.00pm finsh = 4.30pm

In to days task we learend about starter motor and the one we studied on was called pre engage starter.

Then we did a no load test on  20 dCV to get the voltage and the amps on 20 k

That showed us our voltage was less then 11 so that means its not good however our current was above 50 amps that showed a good sign.

Testing Armature

we had to do a visual inspection of our starter motor to check for any physical damage and then did a component test report as showen below

                                 component test report                  

Armature	Manufacturers spesification	Test reults	serviceable
overheating	visual inspection	no sign	Yes
burning	visual inspection	no sign	yes
physical damage	visual inspection	no sign	yes
poling	visual inspection	no sign	yes

That showed us that the armature is in good condition and no physical damage.

                                                                             Ground circuit test

we used a multimeter in the ohms range to check the ground short circuit between each of the commutator segments and the armature core of shaft .

                                                    Armature ground test

manufacturers specifications	test results	serviceable
Infinity	good	yes

That showed us that ground short circuit between the two components are in good conditions and its serviceable.

                                                                     Continuity circuit test

we had to do a continuity circuit test with the ohmmeter 20k in the same range we checked the continuity between on of the commutator segments while moving the second probe around on each of the other commutator segments.

                                              Armature continuity test

The test results showed use that the continuity circuit is good it stayed between 0 and 1 ohms so its good and serviceable.

                                                              Testing commutator

we had to measure the commutator diameter and to measure the mica undercut depth as necessary. but some materials used to insulate the segments it does not require undercutting.

                                                          commutator test

Manufacturers specifications	test results	serviceable
Minimum diameter 26.8mm - 31 mm	31.4mm	yes
mica undercut  0.7mm -1.0mm	0.2mm	yes

That showed our diameter is good is not below the minimum measurement so is our mica undercut as you see above.

                                                                Armature shaft

we had to check the armature run out by placing it between the v blocks and then turn it 360 clock wise while reading the dial test indicator.

                                            Armature run out test

Manufacturers specifications	test results	serviceable
0mm- 0.2mm	0.03mm	yes

thats showed us that our armature runout is in good condition no damage on the armature.

                                      Alternative method of testing Armature

We had to test the Armature using 48 volts test light. Then we did our continuity test by keeping one of the probes on one segment and move the other prob around each of other segments. Then we did our ground test by placing one probe on any commutator segment and the other on either thr armature core of shaft. and the test light should not glow if it glows there is a faulse.

                                    Armature continuity and ground test

Manufacturers specifications	test results	serviceable
continuity test light on over each segment	good	yes
grounded test light of	good	yes

That showed us the continuity test on the armature is good no faulse segments happend.

                   Testing for internal short circuit using growler

• first thing we did was place the armature on the "v" of the growler
• Then turned the switch on to the Growler position
• and then we hold a hacksaw blade along the armature and then rotated the armature 360 clock wise.

                                                         Armature internal short test

 

manufacturers specifications	Test results	serviceable
hacksaw blade will vibrate when placed over shorted winding indicatin a shorted armature	good	yes

                                    Test the field coils for continuity

The next method was to test the field coils for continuity by checking for continuity in the field winding place probes on each end of the field winding . and it depends on the design of the starter motor circuit, field winding maybe grounded or insulated from the field housing. by placing the multimeter field coils.

                                                   component test report

  

field coils continuity	Manufacturers specifications	test results	serviceable
if grounded	Test N/A	0.00	yes
Not grounded	0 - 0.02 ohms	0.00	yes

our component test reports shows that the field coils for continuity is good .

                                                 Test the field coils for grounding

we check the field grounded by placing the positive probe on the field wire or bruch, then the common probe on the boday of the starter , then the meter should read infinity

                                  component test report

field coils grounding	Manufacturers specifications	test results	serviceable
if grounded	0 - 0.02
not grounded	infinity	Tick	Yes

                                                                     












Brushes

The next thing was to measure the length of the brushes and inspect for cracks and other damages that may accour.

Brushes somtimes have  a scribed line on one face or refer to specification sheet for allowable length

NOTE: when considering the brushes for replacement remeber that the starter may not be removed from a vehicle for over 100,00 kms. if the brushes are close to the minimum you should replace with new brushes and they about 14mm long.

                                                           
Component test report

Brushes	manufacturers specifications	Test results				serviceable
Minimum lenght	5mm	15.1mm	15.1mm	15.2mm		yes

This showed us that our brushes is in good condation and well above the minimum length.

                                        

                                       Brush  Holder Assembly

First thing we had to do was to check for short circuit between the insulated brushes and the holder set and the ohms meter on the lowest resistance. we placed on of the probes on the brush and the other one on the metal retaining plates .

                                            component test report

Brush Holder assembly	manufacturers Specifications	Test results	Serviceable
Grounded holder	0-0.2ohms	.001	yes
Insulated holder	Infinity 00

this showed us that our brush holder was .001ohms when its grounded but didnt show any sign of infinity holder. so its still serviceable.

                                 

                                                           Solenoid Magnetic switch

first thing we had to do was to identify termainals so tht will show us and indea oh what they are and can help in future. first thing was " B" Battery supply "S" ignition / starter switch supply and "M" Starter motor supply.

Then we moved on to the Pull In winding test. we connected 9V to the power supply between S and M to measure the amps. Then we placed that on for 5 second  beacause it may prevent and heat that can damage the windings.

                                                             

                                   Component test report

pull in winding	Manufacturers specifications	Test results	Results
current Draw	8-12amps	15amps	No
Physical Action	the plunger should pull in	Yes	Yes

Then we got our results for amps whic h was 15amps thats over the current draw which is not good and its not serviceable . it had to be between 8 - 12amps that will show a good sign.

                                                                        Hold In Test

First thing was we connected 9V power supply between S and the solenoid body. then we pushed the plunger in by hand and then released it. it was poping in and out.

                               Component Test  Report                                          

Hold in winding	Manufacturers Specifications	Test Results	Serviceable
Current draw	5 - 8amps	9amps	Yes
Physical action	The plunger should remain in. when the power is disconnected the plunger should release	yes	yes

                                                                
Both our current draw and physical action showed good sign it did what it said it will do  current just above the minimum amps and the plunger released afetr disconnected the power.

                     Pinion Gear and overrunning or one way clutch

first thing was to check pinion for gear damage and smooth movement along the armature shaft.

Then we turned the pinion gear in the direction of motor rotation, it should free wheel and against direct of rotation it should lock.

Visual inspection

Drive	manufacturers specifications	Test results	Serviceable
Pinion gear	Visual inspection	Good	YEs
bushes	visual inspection	Good	Yes
Clutch	Visual inspection	Good	Yes

 This showed us that our all components that we tested were fine and that they can be used again. we had no potential failer that needed placing. the ( pre engage starter motor ) was a serviceable starter.

The thing was needed to get fixed is the brushes and the thing that needed be done to them is wild them back togather and they should be fine.