4-50. TRACTION MOTOR BRUSHES AND BRUSH HOLDERS (cont)
Position brush holder (14) in traction
Install clamp (13), bolt (11), and
lockwasher (12). Finger tighten bolt
only. Connect electrical lead.
Raise spring (9) and install brushes
(10). Release spring.
Install screw (6), lockwasher (7), and
flat washer (8).
Keep the underside of the brush
holder carbon box within a minimum
commutator and tighten bolt (11).
Connect small spring scale to the spring directly over the brush and pull straight up in line with the brush travel
until the spring is just clear of the brush. The pressure should be between 8 and 10 pounds (3.6 and 4.5 kg).
Adjust spring pressure as follows:
Insert a piece of 1/8-inch (3.2 mm) diameter drill rod in the tension barrel and relieve the tension on the
Remove the cotter pin and increase or decrease the tension as required by rotating the tension barrel.
Install the cotter pin. Check tension.
Start locomotive in accordance with paragraphs 2-10 and 2-11. Apply soft stone to commutator and run
locomotive at half speed (no load) until the commutator is polished and brushes are seated.
Position bottom cover (5) and install capscrews (3) and lockwashers (4). Install top cover (2) and secure with