ISSUE DATE:
SERVICE BULLETIN SUBJECT:
VINs or MODELS AFFECTED:
COMPLETE BY:
SERVICE BULLETIN #:
Labor Operation Code:

1-21-2021
Duopower Gearbox Lock Washer Retrofit
Service Specified Buses
Next Service Opportunity
SC-21-8
PP43Z

NOTICE! It is expected that this process will require 10 person-hours per bus. It is
recommended to use two associates for this work. Please schedule appropriately
to minimize vehicle downtime.

DUOPOWER GEARBOX LOCK WASHER RETROFIT
Retrofit Description:

This procedure updates the locking washers on the gearbox for improved reliability.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

1|Page

Tools/Parts Required
Tools and Supplies Required:
•
•
•
•
•
•
•
•
•
•
•
•
•
•

Approved Wheel Lifts (4 Required)
Jack Stands (4 Required)
Approved Lifting Device for Duopower Axle
Ratchet
1/2-Inch Drive Pull Handle
10mm Socket
13mm Socket
16mm Socket (6-Point)
TMFS 5 Socket (Proterra P/N 120-7746)
1/2-Inch Drive Pull Handle
Calibrated Torque Wrench
Offset Adapter for Torque Wrench (Proterra P/N 128-2242)
Flashlight
Orange Paint Pen

Parts Required:
•
•

125-6417
001912

WASHER, LOCK
CABLE TIE, 11.5 BLACK 292MM"

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

2 EA
10 EA

2|Page

Procedure:
1. This procedure requires the removal and replacement of the Duopower Axle from the bus.
The Axle removal and replacement procedures are included in the Maintenance Manual
applicable to the bus that you are working on. Prior to beginning the procedure, you should
familiarize yourself with the removal and replacement procedure for the Axle in the
Maintenance Manual as well as the procedure in this document. The latest version of the
Maintenance Manual should be downloaded from the following location before beginning the
procedure.
\\bus.local\files\Engineering\Service Bulletins\Service Bulletin Files for SC-21-8
2. Complete the Proterra approved Lockout/Tagout procedure to make the bus safe for work.
3. Lift the bus using Wheel Lifts and support it with Jack Stands to access the Duopower Drive.
4. Refer to the Maintenance Manual for lifting the bus and the removal and reinstallation of the
Duopower Drive.
5. Using a 10mm Ratchet/Socket, remove the top covers from the Duopower Axle.

6. Using a 13mm Ratchet/Socket, remove the bolts that secure the Harness Brackets (046740)
to the Duopower Drive.

7. Carefully remove the Harness Brackets (046740) from the Gearboxes.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

3|Page

8. Access one of the Gearboxes through the area where the Harness Brackets (046740) were
removed. Cut any Cable Ties (001912) necessary to access the gearbox.

9. Using a Ratchet with a 6-Point 16mm Socket, remove the black dust cover shown in the
following photograph.

10. Using a Flat Blade Screwdriver and a small hammer, bend the locking tab of the installed lock
washer upward so that the Lock Nut may be removed.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

4|Page

11. Using a 1/2-Inch Drive Pull Handle with a TMFS 5 Socket, remove the Lock Nut.
12. Inspect the removed Lock Washer. Is the ID Tab within the axel shaft keyway? Is the ID Tab
Damaged? If the Lock Washer is damaged, take a photograph of it and email it to
[email protected].
13. If the ID Tab of the Lock Washer is not in the keyway, rotate it until it is.
14. Using Needle Nose Pliers, remove the Lock Washer.
15. The following photographs show the difference between the old style of Lock Washer and the
new L-Tab Lock Washer (125-6417).

16. Place the Lock Washer (125-6417) into position with the L-Tab facing outward toward the
Wheel Ends (facing away from you). The Outer Diameter Tabs will be facing inward toward
the nut (facing you).

L-Tab

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

5|Page

17. Replace the Lock Nut that was removed earlier and hand tighten it.

18. Using a Calibrated Torque Wrench with an Offset Adapter set at ninety degrees, torque the
Lock Nut to 33 foot pounds. Use a pry bar between the wheel studs to prevent rotation
when torqueing the Lock Nut.
Note: The 1/2-Inch Driver Square may be removed from the offset adapter and inserted into
the TMFS 5 Socket and used with a 15mm Wrench on the square to snug the lock nut before
torqueing.

19. If you cannot torque the lock nut with the Torque Wrench set at 90 degrees to the offset
adapter, place the torque wrench at 180 degrees to the offset adapter and use the equation
below to determine the proper setting for the Torque Wrench. For example, you may need to
set the Torque Wrench to 30 foot pounds to achieve 33 foot pounds at the lock nut.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

6|Page

20. After torqueing the Lock Nut, observe the Lock Washer (125-6417) to determine if one of the
Outside Diameter Tabs aligns with one of the four slots in the Lock Nut.
21. If none of the Outside Diameter Tabs align with a Lock Nut Slot, continue using the Torque
Wrench to tighten the Lock Nut until a Tab is in alignment. Do not exceed 50 foot pounds of
Torque.
22. Using a Flashlight, inspect the Lock Washer (125-6417) for damage. If the Lock Washer is
damaged, it must be replaced with one of the spares from the kit.
23. Using a Flat Blade Screwdriver or a Pick, bend the Outside Diameter Tab into the slot on the
Lock Nut.

24. Using an Orange Paint Pen, mark the bent Tab.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

7|Page

25. Using a Ratchet with a 6-Point 16mm Socket, replace the black dust cover shown in the
following photograph.

26. Using a Calibrated Torque Wrench with a 6-Point 16mm Socket, torque the Dust Cover to
12 foot pounds.
27. Mark the Dust Cover with the Orange Paint Pen.
28. Using an Orange Paint Pen, paint the letters “NLW” in large print onto the suspension arm
closest to the gearbox where the Lock Washer (125-6417) was replaced as shown in the
following photograph.

Mark the Suspension Arm

29. Repeat the process to replace the Lock Washer (125-6417) on the other gearbox.
30. Carefully replace the Harness Brackets (046740) back onto the Gearboxes.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

8|Page

31. Using a 13mm Ratchet/Socket, replace the bolts that secure the Harness Brackets (046740)
to the Duopower Drive.

32. Using a Calibrated Torque Wrench with a 13mm Socket, torque the bolts to 27 foot
pounds.
33. Using an Orange Paint Pen, mark the properly torqued bolts.
34. Using a 10mm Ratchet/Socket, replace the top covers on the Duopower Axle using the
original hardware.

35. Using a Calibrated Torque Wrench with a 10mm Socket, torque the bolts to 11 foot
pounds.
36. Using an Orange Paint Pen, mark the properly torqued fasteners.
37. Record the Axle Serial Number on the Work Order.
38. Refer to the Maintenance Manual for replacing the Duopower Drive and lowering of the bus.
39. Remove the Lockout/Tagout Devices and return the bus to service.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

9|Page