Page 288 - Reciprocating Compressors Operation Maintenance

Overhaul and Repair of Reciprocating Compressors 273

I _» «~ End Clearance f

\\ End Clearance i

FIGURE 4-27. Butt or step joints in piston rings.

Multiply Value
In Table x .71
Multiply Value
~ &X.87
FIGURE 4-28. Angle joints and gap multipliers referred to in Table 4-4.

End Clearances

One simple method of checking end clearance is to insert each ring in
the cylinder at its smallest or unworn section and check end clearance
with a feeler gauge. On small bore cylinders, it may be difficult to make
a measurement. In this case, a fixture or jig can be made. Turned to the
exact bore measurement, it will facilitate measuring the end gap. If clear-
ance is insufficient, the ring ends should be filed. It is better to have too
much than too little end clearance. If the ring is segmental, all but one cut
should be held closed and a feeler gauge inserted at the open joint. Any
filing to adjust clearance needs be done at one joint only.
When checking an angle cut ring, both ends of the ring must be held
against a flat surface such as the end of the piston or another ring. A jig or
fixture with a square shoulder will again simplify the measuring task.