Heavy Duty Balanced Opposed Compressors - Ariel Corporation

FOR MODELS: JGZ AND JGU SECTION 5 - MAINTENANCE
Chain Adjustment
1. Roll the crankshaft to the
tightest position of the
chain. This prevents snugging
up on the chain at a
slack position and breaking
rollers, or ruining the
pump and lubricator bearings
when the chain goes
through its tightest position.
2. Measure the length of the
longest most easily accessible
span with a tape
measure (sprocket center
to center), where the
deflection will be gauged.
Determine the allowable
deflection limits defined by
the shaded areas in Figure
5-20 or Figure 5-21, for the
2 to 10 lb
(9 to 45 N)
Finger
Pressure
Straight
Edge
Machinist’s
Scale
Span
Length
FIGURE 5-19 CHAIN DEFLECTION MEA-
SUREMENT - TYPICAL
measured span (3 to 5% of the span).
3. Measure chain deflection from a straight edge held on the chain rollers where it
wraps over the two sprockets of the span. Use a machinist’s scale with 0.01 inch
or (0.5 mm) increments to measure the deflection distance from the straight
edge to a chain roller at the center of the span. Apply a force of 2 to 10 lb (9 to
45 N) finger pressure to take the slack out of the chain. Do not apply excessive
force since a force feed lube box drive shaft can bend and provide an inaccurate
deflection measurement. Finger pressure is adequate.
4. If adjustment is required, remove the capscrews and plastic plugs from the
eccentric cap. Rotate the cap clockwise, facing cap from outside, to line up the
first two new capscrew holes. If this makes the chain too tight, try turning the cap
around in a counterclockwise direction for a different hole lineup.
5. Replace and tighten the two capscrews hand wrench tight.
6. Roll the crankshaft to check the tightness in a number of positions. At its tightest
position, the chain is to be adjusted so that the deflection is within the shaded
graph limits in the figures. Replace the plastic caps to keep the holes clean.
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