Ariel JGJ Series, Technical Manual

Page: 78 / 141

F
OR
M
ODELS
: JGW, JGR
AND
JGJ S
ECTION
5 - M
AINTENANCE
PAGE 5 - 6 1/01
1. Remove crosshead guide side covers and cylinder head.
2. Move the crosshead to its inner dead center position and back off, but do not
remove, the crosshead nut set screws. Loosen the crosshead nut with the spe-
cial slugging Peg or Open End Wrench shown in Figure 7-1: on page 7-3,
depending on nut style.
3. Use the Piston Nut Spanner (Torquing Adaptor) shown in Figure 7-1: to screw
the piston rod out of the crosshead. The two dowels on the Adapter fit holes in
the piston nut. Turn the crosshead nut off the piston rod. Push the rod end for-
ward to the edge of the packing to provide a clearance for crosshead removal.
4. With the crosshead in its outer dead center position, remove the crosshead pin
thru bolt, lock nut, end-plates and pin.
5. Turn the crankshaft to its inner dead center position. Move the crosshead to its
outer dead center position to be free of the connecting rod. Make sure the con-
necting rod does not drop and damage the crosshead guide surface.
6. Roll the crosshead 90 degrees and remove it through the guide opening.
7. Check the crosshead pin to bushing clearance. (See Table 1-3 on page 1-9.)
Wear on the pin can be determined by a visual inspection. Replace the pin if
necessary. If the bushings need to be replaced, hacksaw or file to within 1/32
inches (1 mm) of their thickness. They can be easily drifted out. A press will be
needed to install new bushings. The bushing can be installed in the crosshead
by cooling the bushing in a dry ice and alcohol solution. The bushing needs to
be left in the solution long enough to reach the same temperature as the solu-
tion, about -120° F (-85°C). DO NOT TOUCH COLD SURFACES WITHOUT
PROPER INSULATION TO PREVENT INJURY. Gray iron crossheads (JGW)
and bronze crossheads do not have bushings; if the crosshead pin bearing area
is worn, these crossheads should be replaced.
NOTE: THE SIDE OF THE CROSSHEAD RECEIVING THE NEW BUSHING SHOULD BE
SUPPORTED DIRECTLY TO PREVENT POSSIBLE CRUSHING OF THE
CROSSHEAD BY THE PRESS. (SEE FIGURE 5-3:)
ABSOLUTE CLEANLINESS IS REQUIRED OF BOTH BUSHING AND CROSS-
HEAD TO PREVENT DIRT FROM ACCUMULATING BETWEEN THE BUSHING
AND CROSSHEAD BORE.
8. Visually inspect the shoe surfaces for scoring. Since they are constantly lubri-
cated under pressure during operation, there should be virtually no wear.
CAUTION
CROSSHEADS ARE HEAVY. CARE MUST BE TAKEN WHEN
HANDLING TO AVOID PERSONAL INJURY. THE WEIGHT OF
EACH CROSSHEAD IS LISTED IN THE BALANCE SHEET
THAT COMES IN THE MANUAL WITH EACH COMPRESSOR.
!