itted by cutting a strip of No. O sandpaper about the
width of the commutator surface. (Have the dynamo idle.) Place the strip
of sandpaper under the brush on the commutator with the rough side
towards the brush, then pull the sandpaper from right to left; continue
this process until the brush has been fitted to a true smooth bearing.
Then trim about one-eighth of an inch off the front edge of the brush.

45. Q. Is it advisable to ever try to fit a brush up with a file or
knife?

A. No.

46. Q. Why is it important to clean the scale off the point of the
copper electrode each trip?

A. To allow the point of the carbon and the electrode to touch to form a
circuit; this scale being a non-conductor of electricity and with it on,
the current would not pass from the carbon to the electrode and holder.

47. Q. How should the copper electrode be trimmed at the point?

A. Copper electrode should have about 1/4-inch surface at contact point.

48. Q. How far should the copper electrode project above the holder?

A. One inch.

49. Q. Should the electrode be raised up to 1-1/2 inches, what might
happen?

A. If the copper electrode was run at a point so near the clutch, the
intense heat of the arc might do damage to the top carbon holder and
clutch.

50. Q. If the dash pot should be found stuck, would you put oil in it?

A. Coal oil should be used to clean and cut the dirt out of the pot and
from off the plunger, but after the dash pot and plunger have been
cleaned all oil should be wiped off of same, as the oil would cause the
plunger to collect dirt and stick.

51. Q. If one carbon of lamp should "jig or pound", what can be done to
stop it?

A. If the carbon jumps or pounds the electrode, it is evident that the
iron armature is too far out of the solenoid, or the speed is too low.

52. Q. Does the pounding of the lamp occur with the old series wound
machines or with the new compound wound machines?

A. The pounding of the lamp occurs with the new compound wound machines.

53. Q. If the copper electrode was fusing, how would you know it?

A. By the fact, when copper is fused a shaft of green light will be
thrown off instead of a shaft of white light.

54. Q. What should be done when a green light is seen?

A. Close the throttle to turbine engine, then open slowly until a white
light re-appears.

55. Q. What is the cause of the copper electrode fusing?

A. The cause of the copper electrode fusing is due to