41. Inspect the ring gear (35), planetary assembly (36), and the axle-shaft lock
nut/lock washer assembly (37) for damage.
Record the inspection results on the vehicle’s maintenance log.
IMPORTANT: If significant damage is present, a replacement gearbox is
needed. Refer to the Gearbox Removal and Replacement procedure in the
vehicle’s maintenance manual.
Record the new gearbox serial number on the vehicle’s maintenance log.

45. Remove and discard the snap ring by prying the tapered end inward and
pulling upward using a screwdriver (or pick) and needle-nose pliers.
46. Coat the replacement snap ring with gearbox oil and install the replacement
snap ring (39) onto the front housing cover, tapered end first.
IMPORTANT: The replacement snap ring is a different design.

42. Ensure the oil passageway o-ring (38) is present and seated on both sides.

39
39

37

35

36

Figure 9-13. Snap Ring Removal and Replacement

38

Figure 9-12. Gearbox Inspections

43. Clean debris that may have fallen into the gearbox and clean the mating
surfaces between the gearbox front housing cover and the gearbox.
44. Cover the open gearbox housing with a plastic sheet to prevent internal
gearbox contamination.

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47. Clean exposed gearbox opening and carefully position the gearbox front
housing cover (34) onto the gearbox.
NOTE: It may be necessary to rotate the input spline by hand if internal gearing
does not easily align. Do not insert tools into the input spline.

49. Temporarily install two 19 mm gearbox mounting bolts (41) into the #4 and #10
torque pattern positions, as shown.
Simultaneously tighten both bolts to fully seat the front housing cover onto the
gearbox. Do not torque.

WARNING: Do not rock the front housing cover side-to-side or internal gearing
damage may occur.
48. Carefully align the gearbox front housing cover (34) onto the two gearbox
dowel pins (40).

41

#10

40

34

40

#4
Figure 9-15. Gearbox Front Housing Cover Re-installation (2 of 2)
Figure 9-14. Gearbox Front Housing Cover Re-installation (1 of 2)

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50. Apply Loctite™ 243 to each of the thirteen new gearbox front housing cover
mounting bolts (42) and install with the retained washers. Torque to 26 ft-lbs (35
Nm) in the torque sequence shown using a 13 mm socket and apply torque
stripes.

#1

#5

#7

#3
#10

#9

CAUTION: There is a risk of breaking mounting bolts due to over-rotation.
Stop torquing if the mounting bolt “feels” at risk of breaking, and leave the
mounting bolt in place as is.

#1

#12
#4

43

42

#13
#5

#8

#9

#4

#6

#7

#10

#11

#2

#3

Figure 9-16. Gearbox Front Housing Cover Mounting Bolts Torque Sequence

#8

#6

#2

Figure 9-17. Gearbox Mounting Bolts Torque Sequence

55. Re-install the gearbox inlet (29) and outlet (30) oil hoses and fittings using a
7/8” wrench. Torque to 60 ft-lbs (81 Nm) and apply torque stripes.
NOTE: If challenges in torque tooling availability exist, tighten fittings to
approximately 60 ft-lbs (81 Nm).
56. Plug-in the temperature sensor (28).

51. Remove the two temporarily installed 19 mm gearbox mounting bolts (41).
52. Clean all ten gearbox mounting bolt holes/threads using brake cleaner (or
equivalent). Clean out the brake cleaner using shop air.
53. Liberally apply Loctite™ 243 to each of the ten new gearbox mounting bolts
(43) and install with the retained washers. Torque to 65 ft-lbs (88 Nm) in the
torque sequence shown using a 19 mm socket.
54. Torque each of the 19 mm gearbox mounting bolts (43) a second time to
80 ft-lbs (108 Nm) in the torque sequence shown.

57. Secure the breather hose (31) to the brake cannister with a new cable-tie.
58. Apply a large “SR” with torque stripe paint on an open area of the SN plate to
annotate the snap ring replacement. This step is critical to prevent costly
duplicate work.

Curb-Side Gearbox Snap Ring Replacement
59. Repeat steps 35 thru 58 on the curb-side gearbox.

CAUTION: There is a risk of breaking mounting bolts due to over-rotation.
Stop torquing if the mounting bolt “feels” at risk of breaking, and leave the
mounting bolt in place as is.

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Traction Motors Re-Installation
60. Apply Loctite™ 243 onto each traction motor stud (44).

27

61.Carefully raise the traction motor (27), horizontally aligning the output shaft
splines and traction motor studs (44) into the gearbox.
44

NOTE: It may be necessary to shift the gearbox into gear by pressing and
holding the manual shift button (45) on the shift solenoid (46). While the holding
the manual shift button (45), rotate the tires slowly until the traction motor
splines align with the gearbox input splines, allowing the traction motor to slide
forward.
62.Firmly push the traction motor fully flush onto the gearbox.
63. Install retained 10 mm traction motor stud locknuts and spacers (26) onto
each traction motor stud and hand-tighten.

26

64.Torque the eight locknuts (26) to 13 ft-lbs (18 Nm) in the torque sequence
shown using a 12-point 10 mm torque wrench adapter.
NOTE: Set the angle between the torque wrench and the torque wrench
adapter to 90° to maintain accurate torque setting.
Figure 9-19. Traction Motors Re-Installation (2 of 2)

65.Final torque each locknut (26) to 27 ft-lbs (37 Nm) in the torque sequence
shown and apply torque stripes with a paint pen (not torque paint/paste).
66.Carefully remove the lifting device from underneath the traction motor.

#1
#8

#5
45

#4

#3
46

#7
#6

NT

O
FR

#2
Figure 9-18. Traction Motors Re-Installation (1 of 2)

Proterra Operating Company, Inc.

Figure 9-20. Traction Motor Mounting Locknuts Torque Sequence

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67.Re-install each phase cable ground clip (25) and route each of the three phase
cables through the cord grips on each traction motor.

70. Inspect all phase cables for chaffing and ensure all phase cables are secured
with the proper cable-ties and mounting blocks.

68. Apply Loctite™ 222 to each phase cable stud (47).

71. Tighten each cord grip cap (23) using the 30 mm Crow’sFoot tool (see Tools
table). Torque each cord grip cap to 62 in-lbs (7 Nm) and apply torque stripes.

69. Install the phase cables (24) with the retained fasteners in one of the two
fastener sequences shown using a 13 mm socket. Torque to 15 ft-lbs (20 Nm).
Do not apply torque stripes.
WARNING: The phase cable fasteners must be properly installed in one of the
two fastener sequences shown, or serious damage to the traction motor will occur.
FASTENER NOTE: Each phase cable stud should have a copper spacer (48)
below the phase cable lug (49), and a 13 mm nut (50) above the phase cable lug
(49).
If present during disassembly, the conical washer (51) or serrated washer pair
(52) should be re-installed between the phase cable lug (49) and the 13mm nut
(50).

72. Re-install the phase cable box cover (21) and the phase cable box guard (20)
on each traction motor using a 3 mm hex-head wrench. Torque to 18 in-lbs (2
Nm) and apply torque stripes.
73. Re-connect the traction motor coolant hoses (16) to the traction motors using
a 1” wrench. Torque to 60 ft-lbs (81 Nm) and apply torque stripes.
NOTE: If challenges in torque tooling availability exist, tighten fittings to
approximately 60 ft-lbs (81 Nm).
74. Re-install all brackets (18) to each traction motor using a 15 mm socket/
wrench. Torque to 20 ft-lbs (27 Nm) and apply torque stripes.
75. Secure the curbside gearbox oil hoses (29, 30) to each lower motor bracket
using cable ties.
76. Re-connect each low-voltage connector (17) to each traction motor.

50

77. Re-install the traction motor ground cables and ground cable fasteners (19)
using a 15 mm socket. Torque to 25 ft-lbs (34 Nm) and apply torque stripes.

25

52

24
49

78. Re-install the ECU bracket/ECU (10) and fasteners (11) using a 10 mm
socket/wrench and reconnect the ECU harness connector (9).

48

79. Remove lockout/tagout.

50
51

25
24

49

47

48
23

Figure 9-21. Phase Cables Connection

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Gearboxes Fluid Fill

84. Run the oil pumps for one minute to circulate oil through the oil module and
gearboxes to remove potential air pockets from the system:

80. Verify each gearbox oil drain plug (12) is torqued to 18 ft-lbs (24 Nm).
81. Remove and retain the gearbox oil fill plug (53) on each gearbox using a 6 mm
hex-head wrench.
82. Fill the gearboxes with fluid until full in the oil sight glasses (54) using a fluid fill
pump. Let the oil settle for ten minutes, and refill until full in sight glass.
83. Temporarily install the oil fill plug (53) on each gearbox. Do not torque.

• Select ON at the Service Disconnect Switch (55).
• Select ON at the Master Disconnect Switch (56).
• Select Day Run at the Driver’s Master Switch (57).
Wait one minute, then:
• Select OFF at the Driver’s Master Switch (57).
• Select OFF at the Master Disconnect Switch (56).
• Select OFF at the Service Disconnect Switch (55).
57

53

T

ON

FR

54
56

12

Figure 9-22. Gearboxes Fluid Fill
(traction motor shown removed for clarity)

Proterra Operating Company, Inc.

55

Figure 9-23. Switch Locations

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85. Remove the temporarily installed oil fill plug (53) and fill the gearbox with fluid
until full in the oil sight glass (54) using a fluid fill pump.
86. Apply a small amount of gearbox fluid to the oil fill plug (53) O-ring seal.
Re-install and Torque to 13 ft-lbs (18 Nm).
87. Re-install both motor bridge harness brackets/bolts (8) using a 13 mm socket/
wrench.
88. Re-install all six axle covers (6) and fasteners (7) using 10 and 13 mm
sockets/wrenches. Torque to 8 ft-lbs (11 Nm).
89. Re-install the skid-plate (4) and fasteners (5) using a 15 mm socket/wrench.
90. Re-install the high voltage cable guard (2) using a 10 mm socket/wrench.
91. Re-install the large front cage dust cover (1) using a 10 mm socket/wrench.
92. Record both snap ring replacement procedures, the odometer reading,
inspection results, and all gearbox/traction motor serial numbers on the
vehicle’s maintenance log.

Power Electronics Coolant Loop Fill
NOTE: Use only 50/50 ethylene glycol/distilled water mixture.
93. Lower the bus to the ground.
94. Attach a 3/8" EPN coolant fill hose onto the coolant fill port (58)
95. Insert the other end of the 3/8" EPN hose into the coolant supply container.
96. Select the motor coolant fill (Power Electronics) position on the coolant loop
selector three way valve (59).
97. Toggle the coolant fill pump switch (60) to the “ON” position until the coolant
level is full in the rooftop reservoir, ensuring that the coolant level is full in the
translucent fill tube (61).
NOTE: Open the rooftop emergency escape hatch for translucent fill tube (61)
visibility.

NT

FRO

T

ON

FR

61

60

59

58

Figure 9-24. Power Electronics Coolant Loop Fill

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Pairing the Traction Motor and Power Inverter
NOTE: The traction motor pairing procedure is only necessary if a traction motor
is replaced or if a traction motor does not pair automatically when re-installed.
Additional information about the Proterra Diagnostic Tool can be found in the OnBoard Diagnostics chapter of this maintenance manual.
Required Tools
•

Laptop computer with the latest version of the Proterra
Diagnostic Tool.
https://diag.proterra.com/

•

Nexiq USB-Link 2
Diagnostic
Port

Figure 9-26. DuoPower Powertrain Screen

Rear Deck
Laptop

Nexiq
USB-Link 2

Figure 9-25. Required Tools for Pairing the Traction Motor & Power Inverter

NOTE: Vehicle Diagnostic Port locations vary by configuration. The above
illustration shows a rear deck diagnostic port configuration.
If no diagnostic port is present on the rear deck, use the OBD II diagnostic port
located in the street-side wheel-well ITS area.

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98. Power down the vehicle by:
• Selecting OFF at the Driver’s Master Switch (57).
• Selecting OFF at the Master Disconnect Switch (56).
• Selecting OFF at the Service Disconnect Switch (55).

100. Connect the laptop to the Nexiq USB-Link, and the Nexiq USB-Link to the
vehicle diagnostic port.

99. Power up the vehicle by:
• Selecting ON at the Service Disconnect Switch (55).
• Selecting ON at the Master Disconnect Switch (56).
• Selecting Day Run at the Driver’s Master Switch (57).

102. Select Powertrain.

101. From the laptop, launch the Proterra Diagnostic Tool, and select Connect.

103. Select Pair Motor with Inverter.
104. When prompted, turn on high-voltage by pushing the green Start button on
the driver's dash.

57

NOTE: A message confirming a successful traction motor/power inverter pairing
will appear.
105. Turn the driver’s master switch to the OFF position, and then back to the ON
position and return the vehicle to service.

T

ON

FR

56

55

Figure 9-27. Switch Locations

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