SINGER 251 - Manual (Page 44)

44
THE ARM SHAFT (continued)
S3
HOLD THESE GEARS IN MESH
Fig. 70. Replacing the Arm Shaft
REPLACEMENT-
(See Fig. 70)
CAUTION: Make certain that the OIL-REMOVING
WICK ASSEMBLY is out of the machine.
1. Insert the machine-pulley-end of the arm shaft
into the arm shaft bushing at the head of the
machine arm.
2. Make certain that the needle bar crank is turned
to the position shown in Fig. 69, clearing the
three wick loops in holder W4.
3. While still holding the bevel gears at S3 in mesh,
with a screwdriver, as shown in Fig. 70, push the
arm shaft X4 straight through the machine arm,
the feed eccentric U4 and the feed-eccentric-and-
bevel-gear X3, Fig. 70. (A light tapping with the
palm of the hand, against the needle bar crank
end, may be required.)
4. Replace machine pulley so that the two set screws
T4 will locate over the two grooves V4 on the
shaft and securely tighten set screws T4.
5. Replace and tighten the arm shaft screw R4
sufficiently to remove all end play of the shaft
without binding. Test the arm shaft for freedom
in rotation.
6. Move bevel gear X3 toward machine pulley and
securely tighten feed timing screw Y.
7. Place the first finger of one hand on one side of
the arm shaft and the first finger of the other
hand on the other side of the arm shaft so that
both fingers contact the bevel gear (on vertical
shaft) that mates with the gear X3. Feel for
slight backlash. If there is no backlash, loosen
timing screw Y and set screw O. Lightly tap gear
X3 away from mating gear until there is just a
slight amount of backlash. Then securely tighten
timing screw Y and the set screws in gear X3. Re­
check the backlash.
8. Using a screwdriver, as shown in Fig. 70, move
feed eccentric U4 as close as possible to the con­
necting rod A2, Fig. 70 and tighten the timing
screw and two set screws in eccentric U4.
9. Check the adjustment and timing of parts dis­
turbed and correct where necessary, according to
the instructions on
pages 18 through 25.
10. Replace the oil-removing wick assembly, as in­
structed on
pages 39 and 41.
11. Replace thread take-up, as instructed on page 35.
12. Replace presser bar and presser foot, as in­
structed on
page 33.
13. Replace the upper needle bar bushing and the
needle bar, as instructed on
page 33.
14. Replace thread take-up oil guard W2, Fig. 54,
page 36.
15. Replace arms side shield and wick, as instructed
on page 36.
16. Replace the oil lead beneath the arm top cover.
17. Replace the arm top cover and tighten its four
screws.
1 8. Replace the face plate and tighten its four screws,
as instructed on page 18.