Cashco DA4 - Manual (Page 9)

IOM-DA4 9
Using thumbs, work the piston ring
seal (27.5) into the groove of the
bearing (13). Repeat this procedure
with a second piston ring seal (27.5).
NOTE: A piston ring as sem bly (PRA)
consists of one metal corrugated
energizer (27.6) and two piston ring
seals (27.5).
4. Position piston-guide bearing (13)
over and into upper end of cage (19)
until the lower piston ring seal (27.5)
touches the upper lip of the cage (19).
While gently applying force to press
the piston-guide bearing (13) into the
cage (19), si mul ta neous ly use fi n gers
to lightly circumferentially press the
fi rst (lower) piston ring seal (27.5)
inwards into the piston-guide bearing
(13) groove until the fi rst piston ring
seal (27.5) “slips into” the cage (19).
Repeat for the second piston ring seal
(27.5).
f. Type UC:
1. Stretch u-cup seal (27.3) over lower
circumference of piston-guide bear-
ing (13), taking care not to “cut”
u-cup seal (27.3) on the protruding
shelf that is part of the piston-guide
bear ing's (13) groove. Ensure that the
u-cup seal (27.3) is oriented with the
center-open-downwards as shown
in Figure 1, as the u-cup seal (27.3)
depends upon the P1-Inlet Pres sure
to pressure activate the seal for proper
sealing action.
2. Position piston-guide bearing (13)
over and into upper end of cage (19)
until the cap seal (27.1) edge touches
the upper lip of the cage (19). While
gently applying force to press the
piston-guide bearing (13) into the
cage (19), simultaneously use fi ngers
to lightly press the u-cup seal (27.3)
inwards into the groove of the piston-
guide bearing (13) until the u-cup seal
(27.3) “slips into” the cage (19). DO
NOT USE TOOLS, LUBRICANT, OR
HEAVY FORCE TO ENGAGE THE
U-CUP SEAL (27.3) INTO THE CAGE
(19).
4. Place properly oriented seat ring (21) onto its
shoul der at the lower end of cage (19).
5. Composition Diaphragm Designs:
a. Place new o-ring lower stem seal (14.3)
into groove of valve plug (20).
b. Insert valve plug (20) upwards through
lower end of cage (19) and through the
center hole in piston-guide bearing (13),
also capturing the camber adjusting
wash er (17.2) or wiper washer (17.1) and
wiper seal (16), if supplied. Hold plug (20)
and cage (19) together.
c. Place an oversized nut or stack of wash-
ers, the same approximate height of the
up per diaphragm pres sure plate (8) and
the lower diaphragm pusher plate (10),
over the upper end of valve plug (20) and
temporarily secure with diaphragm lock
nut (7), manually tightened. Do NOT al low
valve plug (20) to rotate against seat ring
(21) during tightening.
d. This completes ITA preliminary/partial
reassembly.
6. Metal Diaphragm Designs:
a. Insert valve plug (20) upwards through
lower end of cage (19) and through the
center hole of camber adjusting washer
(17.2) or wiper washer (17.1) and wiper
seal (16).
b. Engage valve plug (20) with piston-guide
bearing (13) threads and tighten man u al ly
as far as possible.
c. Place ITA into a vise with leaded jaws and
grasp at a hub location on the valve plug
(20) that is not in the “spindle” zone. (See
Figure 3.)
d. Using a spe cial dou ble-posted span ner
wrench fi t ting (to order see NOTE in Sec-
tion X, Parts Ordering Information), tighten
piston-guide bear ing (13) to the valve plug
(20) with the following torque values. Do
NOT allow valve plug (20) to rotate against
seat ring (21) during tight en ing.
e. This completes ITA reassembly.
F. Main Reassembly:
1. Place body (23) in a vise.
2. Reinstall internal sensing drilled plug (32) with
compatible thread sealant.
3. Insert the lower piston spring (22) into the
body (23), if supplied.
4. Fit the o-ring cage seal (15) into its body (23)
groove.