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a rubber mal let will restore the crosshead O.D. into its
origi nal round ness.
ORDER OF ASSEM BLY
The connecting rod/crosshead assembly is installed
AFTER the assembly of the crankshaft. The rod and
crosshead will pass through the wiper box wall bore.
With the frame in the horizontal position, load the rods
through the cradle.
PRECISION CRANK PIN (CRANKTHROW) BEARINGS
Myers Aplex Series pump crankpin bearings require
no shimming to establish correct running clearance.
Precise machining of the con necting rod, caps and
crankp in journals is neces sary to achieve
this conve nience.
New Crankpin O.D.:
1.750/1.749
New Connecting Rod Bore:
1.8944/1.8954
New Crankpin O.D.:
2.250/2.249
New Connecting Rod Bore:
2.3944/2.3955
New Crankpin O.D.:
2.749/2.748
New Connecting Rod Bore:
2.941/2.942
MA-15M MA-25L MA-40L
MA-15H MA-25M MA-40M
SC-30 SC-45 SC-115
SC-30H SC-45L SC-115L
RO-23 SC-45h SC-115H
RO-38 RO-64
Crankpins that are
worn out-of-round,
tapered, or badly
scored should either
be dis carded or per-
haps salvaged by
grinding under size,
hard chrome-plated,
and finish ground
to above diameter.
Connecting rod /cap bore must be perfectly round and
with in above sizes and free of taper. Discard if elliptical
or tapered as the result of abnormal heat ing. Each cap
and rod is match-marked for correct identification.
Take care that each cap is reinstalled prop erly with its
companion rod. Bearing halves are identical and are
pre vented from rotating by tongues which fit into slots
in the cap.
Check that all oil holes are clean and fully open. GRIT
is the greatest enemy of bear ings, however precisely
manu factured. Hence, all sur faces must be perfectly
clean and lightly oiled prior to assembly. Re move any
burrs or sharp cor ners which pre vent the per fect fitting
of these precision bearings. Using a torque wrench,
tighten cap bolts as follows:
Thread Size:
1/4" – 20UNC
Tightening Torque:
11 Ft. Lb.
Thread Size:
5/16" – 18 UNC
Tightening Torque:
19 Ft. Lb.
Thread Size:
3/8" – 16UNC
Tightening Torque:
26 Ft. Lb.
SC-30 SC-45 SC-65
SC-30H SC-45H SC-65H
RO-23 SC-45L SC-65L
MA-15M RO-38 RO-64
MA-15H MA-25M MA-40M
MA-25L MA-40L
Specified torque, applied to clean, well oiled threads
and bearing faces, will create tensile stresses in
the cap bolts from 90,000 to 110,000 psi, approx.
and will provide correct initial tension. Myers Aplex
Series pumps use high strength cap bolts suitable
for these initial loadings, maintained by hardened
spring lockwashers.
After all rods and caps are secured, slowly turn the
crank shaft to be sure no bearing is in a bind.
Using a flashlight, examine the location of each
connecting rod (eye end) within its crosshead. Rods
must not touch any crosshead boss or skirt.
WIPER BOX ASSEMBLY
GENERAL
Extension rod wiper boxes (sometimes referred to
as the diaphragm stuffing box, or stripper housing
assembly) serve two important functions: retention of
crankcase oil in the power end and exclu sion of dirt
and water.
Myers Aplex Series has developed a unique sealing set
which operates on a hardened and ground stainless
steel extension rod (often called “pony” rod), and a
rubber baffle disc affording protection against leaking
plunger packing. The seals require no adjustment, only
correct and careful assembly.
“POLY PAK” SEAL
This seal keeps oil from leaking out of the power frame.
Developed by the Parker Seal Group, this patented rod
seal employs a soft nitrile rubber O-ring to energize a
special hard polyurethane Molythane
®
shell by forcing
the inner lip against the rod and the outer lip against
the housing bore, as shown.
INSTALLED
WIPER BOX
WALL
CRADLE
OPENING
CROSSHEAD
AND PIN
CONNECTING
ROD
POWER
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