The Norden Bomb Sight manual

Replacement

of

Brushes

Fig.

рд. 135

Commutator

Check

Governor

Care and

Adjustment

of

Gover-

nor Points

3. Brushes.

To remove brushes on the telescope motor

loosen two screws that hold the lower

field pole

plate (from the outside of the housing); move the

field assembly away from the commutator. Remove

both brush

brackets together.

Never looser or

remove fiber terminal block

as this will spoil

radius of brushes.

The telescope motor brushes should be repiacec

the commutator.

The telescope motor brush spring should extend

to a length of 1-3/32 when supporting a 4-1/2 oz.

weight.

Measure to end loop centers.

This spring

comes

long in

spare parts and it will be

necessary, when installing a new one, to clip off

one

co i l

at a time and reform the

end loops as

necessary.

If the commutator is rough,

remove from hous-

ing and

#400 aluminum oxide paper and

crocus cloth.

to put the commutator

in a lathe on

its own bearings and

to rotate the

commutator as

the #400

aluminum

oxide paper and

crocus

are

This will preventlow

spots.

worn it should

If the commutator is very rough, pitted

be turned

lathe on

by an experienced machinest. (This

is a depot or factory job.)

No warm-up

for

required, under ordinary operat-

telescope motor.

Disconnect governor

lever from governor,

armature shaft vertical and close governor by

sandi it should fall under its own weight.

I t

its own weight with

held about 150 out of the vertical.

If pivots

disc speed cannot be adjusted

and it will

clean the pivots with

kerosene,

benzine,

catching

dirt and solvent on

cloth.

Re-oil with

a drop or two of light oil. Wipe off

excess oil.

the stationary point

so that 1/2 of the

governor movement

is regulred in taking up slack,

and the

remaining 1/2 in opening the points.

made on

governor slide and adjusted by

positioning the fixed governor point.

when

they

no

longer

form

an

angle

of

with

and

in

bearings

is

the

should

still

under

shaft

bind,

be

to

Set

check

is