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VILTER MANUFACTURING CORPORATION
VILTER MultiCylinder Compressor
400 Series VMC 2/01
SERVICE - 23 - Replaces all Previous Issues
B. Reassembly (cont’d)
Connecting rod bolts are secured with one plain
steel nut and one spring steel locknut (commonly
referred to as a “Palnut”). The plain nut tighten-
ing torque should be listed in Table 2, 3 or 4 (de-
pending upon compressor model). The torque
wrenches should be set to the high side of the
tightening torque range.
As the rods, bearing inserts and crank pins are
all machine to fine tolerances, no further adjust-
ments are necessary.
FIGURE 13. PISTON RING DIMENSIONS
TABLE 1. PISTON RING DIMENSIONS AND
TOLERANCES
DIMENSION COMPRESSION
RING
OIL RING
A 4.500 4.500
B 0.160 to 0.170 0.170 to 0.180
C 0.1230 to 0.1240 0.1860 to 0.1870
D 0.013 to 0.0225 0.013 to 0.023
E 0.002 to 0.004 0.0015 to 0.004
After a plain nut has been placed on a rod bolt
and torqued to the specified value, turn a Palnut
to the rod bolt with the open end of the hexagon
pointing away from the plain nut. The Palnut
should be turned until mating parts are pulled
together and actual tightening begins.
Final tightening and locking is then achieved by
giving the Palnut an additional 1/3 to 1/2 (maxi-
mum) turn. Although the plain steel nuts may be
reused, new unused Palnuts must be used each
time the connecting rods are reassembled to the
crankshaft. If used Palnuts are installed, their
locking feature is lost and a loose rod connection
may result. After each rod is installed, rotate the
crankshaft by hand to make sure everything is
free and there is no binding of the rotating parts.
CAUTION
Late model VMC compressors may push lin-
ers out.
XIII. CYLINDER LINERS
NOTE:
Before proceeding, refer to Paragraph I, “General
Service Instructions”.
A. Removal
Once the piston and rod assemblies are re-
moved, the liner can be extracted from the frame
by means of a Vilter Liner Pulling Tool (KT 257).
This tool, or similar, is required for all 440/450
compressors and 2-stage compressors.
NOTE:
If the cylinder bank has unloading, the unloader
piston needs to be held down for ease in liner
removal.
The liners in the 450XL compressor have a
looser fit into the frame. They can be removed
by pulling from the bottom of the liner by hand.
NOTE:
2-Stage liners have an extra groove without ring
that seals the suction chamber from the crank-
case.