F
OR
M
ODELS
: JGI, JGM, JGN, JGP
AND
JGQ
S
ECTION
5 - M
AINTENANCE
PAGE 5-30
allow chips to come loose in service. See Figure 5-22 on Page 5-30.
13. Weigh the piston rod assembly with piston rings, and wear bands if applicable,
included. Weigh parts on a calibrated scale to 0.1 pounds (0.05 kg). Stamp the
weight on the piston’s head end. Remove any raised lips caused by stamping
using a fine grit flat stone to avoid clearance measurement errors. Record this
weight for future reference.
Piston and Rod - Installation
1.
With the crosshead, wiper packing and piston rod packing case installed, install
the piston rod assembly with piston rings into the cylinder. The threaded cross-
head end of the rod is 1/8 inches (3 mm) smaller than the inside diameter of the
packing. It is not necessary to use an entering sleeve if reasonable care is
taken, but a plastic sleeve may be helpful to be sure packing rings are not dam-
aged. A piston rod entering sleeve is available from Ariel as a purchased sepa-
rately tool, see Figure 7-2 on page 7-3. See “Piston Rings - Installation” on page
5-32 and “Wear Band - Installation” on page 5-33.
2.
As the piston enters the cylinder, encircle the first ring by hand to allow it to enter
the cylinder without damage. Use the same procedure for succeeding rings, and
wear band if applicable.
3.
Be sure that the crosshead-balance nut seating surfaces are flat and free of
burrs. Dress with a fine grit flat stone as required. The piston threads are to be
lubricated with a thin coat of Never Seez, regular grade, and the crosshead-bal-
ance nut seating surfaces with new oil (same grade as used in the frame).
4.
With the setscrew cup points on the crosshead side of the crosshead-balance
nut, re-install the nut onto the piston rod. Turn nut on to rod threads to allow
enough clearance to attach the rod to the crosshead.
5.
Use the piston turning/piston nut torquing tool a speed wrench to screw the pis-
ton rod into the crosshead. The two dowels on the turning tool fit holes in the pis-
ton nut or piston/rod as applicable.
6.
Follow the instructions in “Crosshead - Installation” on page 5-13 for tightening
the crosshead-balance nut and setting piston end clearance to secure the piston
rod to the crosshead, and for closing the cylinder and crosshead guide. Check
piston end clearance, piston rod run-out and crosshead clearance to specifica-
tions.
F
IGURE
5-22 S
TAKING
C
OMPRESSOR
P
ISTON
N
UT
TO
L
OCK
S
ET
S
CREWS
Piston Nut
Punch Mark within 1/16 in.
(1.5 mm) of Threads to Deform
Piston Nut to Lock Set Screw
w/o Deforming Set Screw
Set Screw
No Cracks or Torn
Material Allowed
