SUBSECTION 4E
CHAINS AND IDLER SHAFTS
6. To cut a roller chain, alternately strike the two pins of a
GENERAL
link out of its link plate. Be sure to alternately strike the pins
This subsection covers the troubleshooting, removal and in-
to avoid distortion of the roller link plates. If the Pins are
stallation of the chains. In addition it covers the removal, re-
"headed". grind off the'heads before driving them through
pair and installation of the idler shaft.
the link plates.
INSTALLATION. To install a chain, wrap the chain around
TROUBLESHOOTlNG
the sprockets, bringing the free ends together on one
sprocket. Insert the pins of the connecting link in the two
A troubleshooting chart at the end of this subsection lists
end links of the chain; then install the free plate of the con-
some of the difficulties which may be experienced with the
necting link, and fasten the plate using the cotter, spring
chains. Remedies are given which may be used to correct a
clip or other fasteners supplied. After the fasteners have
specific problem.
been inserted, it is important that the ends of the chain pins
be tapped back so that the fasteners come up snugly against
CHAIN (20Z1017)
the outside of the connecting link plate.
REMOVAL. To remove the chain, remove the chain case
cover and gasket. Turn the drive until the connecting link is
CHAIN TENSION ADJUSTMENT. To check and adjust the
fully engaged with one of the sprockets, so as to relieve the
chain, proceed as follows (see Figure 4E-1):
tension of the connecting link pins. Loosen chain tension,
then remove the connecting link and lift the chain off the
1. Remove the chain case inspection plate. Loosen four
sprockets.
idler capscrews (see Figure 4E-2).
2. Loosen the jam nut "A" and turn adjusting nut "B"
against yoke to adjust.
INSPECTION AND REPAIR. A chain, like any other oper-
ating equipment, requires inspection to obtain long life and
3. Adjust the chain tension so that there is approximately
satisfactory performance. Inspect the chain as follows:
1/2 inch total midspan deflection at point "X" as indicated
in Figure 4E-1. To tighten the chain, turn adjusting nut "B"
1. Check for wear on the sides of the sprocket teeth and on
to the right; to loosen turn nut in opposite direction.
the link plates. Such wear indicates misalignment.
2. Check for wear on the working faces of the sprocket
teeth. As the drive runs in, these faces should develop a
bright, polished appearance. Scratches, galls, grooves, or
visible changes in tooth form are signs of trouble, probably
Do not adjust the chain too tight as this will
caused by sluggish roller action due to lubrication prob-
cause excessive wear to the chain and
lems.
sprocket.
3. An elongation of as much as three percent indicates that
the chain is riding near its limit of allowable height on the
4. Tighten jam nut "A" against adjusting nut "B". Tighten
sprocket teeth. Gradual increases in chain length are the
four idler capscrews (see Figure 4E-2).
result of normal wear.
4. Check the chain and the sprocket teeth for accumula-
5. Repeat the above procedure for the chain on the oppo-
tions of dirt or foreign materials and for evidence of corro-
site side of the chain case.
sion. Foreign material packed into the chain or sprocket
teeth may cause chain or sprocket breakage.
NOTE
5. Check the lubricant level in the chain case. See the Op-
Both chains must be adjusted evenly to obtain the
erator's Manual for the method of checking the level.
same amount of slack.
