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VILTER MANUFACTURING CORPORATION
VILTER MultiCylinder Compressor
400 Series VMC 2/01
SERVICE - 31 - Replaces all Previous Issues
CONNECTING ROD NUTS TIGHTENING INSTRUCTIONS
VMC COMPRESSORS
All VMC Compressor connecting rod bolts use a plain nut with a spring steel locknut (“Palnut
©
”) combination.
PLAIN NUTS
Plain nuts may be re-used. Torque the plain nuts as follows:
Connecting Rod Assembly
Torque Value
A33171A (Aluminum) 18 to 21 ft. lb. (24 to 28 Nm)
A31045D (Steel) 30 to 35 ft. lb. (41 to 48 Nm)
A34762A (Steel) 30 to 35 ft. lb. (41 to 48 Nm)
LOCK NUTS
New, unused locknuts (“Palnuts”) must be used each time the connecting rods are serviced. After the plain nut is
torqued to the specified value, assemble the palnut to the rod bolt with the open end of the hexagon pointing away
from the hex, plain nut.
CAUTION:
OPEN END MUST POINT AWAY FROM PLAIN NUT. If palnut is installed the other way, it will not lock and
will eventually work loose, during operation.
Turn the palnut until the mating parts are pulled together and tightening begins. Final tightening and locking of the
palnut is achieved by an additional 1/3 to 1 /2 (maximum) turn. Order spare palnuts by Vilter part number 2028A.
SOCKET
A special, shallow hexagon socket is available for easier assembly. This socket is
7
/
8
” in diameter, 2¼” long and has
a
3
/
8
” square socket drive. The socket is specially made for this type of nut, allowing more convenient gripping and
tightening of the palnut. Order Vilter part number 2040A.
TORQUE LIMIT ADAPTOR
Also available is a torque limit adaptor. This lightweight, compact, rugged, and square male drive tool is factory set
to a predetermined torque value. Use with any socket driving device. The adaptor allows the accurate torquing of
the plain nut to the specified value in the confined crankcase space. One adaptor is needed for each different con-
necting rod. Order by part number listed below:
Adaptor Part No.
Drive Overall Dimension Torque Limit Setting Use w/Rod
2287A
3
/
8
” 1
3
/
8
” 19 ft. lb. (26 Nm) A33171A
2287B ½” 1
5
/
8
” 33 ft. lb. (45 Nm) A31045D
2287B ½” 1
5
/
8
” 33 ft. lb. (45 Nm) A34762A