Cashco 1000 HP Differential - Manual (Page 8)

8 IOM-1000HP-Dif fer en tial
d. Place thread sealant on threaded portion
of seat disc screw (26), and manually ro-
tate piston (24) into seat disc screw (26)
(still fi xed in vise) to secure seat disc (25).
Tighten seat disc screw (26) fi rmly. Do not
over-tighten to the point of embedding the
seat disc screw (26) into the seat disc
(25); the seat disc (25) should lay fl at with
no rounded surface. A mechanical aid is
normally not re quired; hand tightening is
normally suffi cient.
7. Insert piston assembly (24 - metal seat) (24,
25 and 26 composition (soft) seat) into end
of cylinder (21).
8. Place piston collar (23) over the end of piston
(24), ensuring that the spherical surface of
the piston (24) and the piston collar (23) bear
against each other.
9. Clean the body (1) cavity through the open-
ings. Clean the “jet area” just inside the body
(1) outlet end through which the piston (24)
projects. Clean all parts to be reused.
10. Use special care cleaning the fl at mating sur-
faces of the body (1) and cylinder (21) shoulder,
as this pres sur ized joint is metal-to-metal with
no gasket. (See NOTE next step.)
11. Lubricate the cylinder (21) threads lightly with
thread sealant. Insert the entire trim stack into
the body (1) opening and screw until tightly
seated. Using the hammer and wrench han dle,
impact the cylinder (21) into the body (1).
NOTES: 1. Take special precaution to keep
pis ton collar from getting “cocked” at an angle
when inserted.
2. On 2" brass bodies (1) with brass trim, a TFE
body O-ring (43) is utilized to seal be tween the
body (1) and the cylinder (21) subassembly.
This O-ring is not indicated on drawings.
12. Inspect the body (1) outlet end to ensure that
the piston (24) is located nearly concentric to
the body (1) bore in the jet area with clear ance.
Under no con di tion should the piston (24) be
touching the body (1). Use two pencils or simi-
lar shafts to place in inlet and outlet ends of
regulator and alternately push on each end of
the piston (24) to ensure free movement. (Total
move ment is ap prox i mate ly 1/8" (3mm).
c. Flow induced wear at expansion zone
where fl uid turns to enter the piston (24)
center.
d. Where the piston (24) ribbed guides bear
(guide zone).
If wear is signifi cant at any of these points,
both cylinder subassembly (21) and piston
sub as sem bly (24 or 24, 25, and 26) should
be replaced. (Cashco does not rec om mend
at tempt ing to replace the seat (21.2) by press-
ing out and then repressing in. Cashco also
recommends that a cylinder (21) and piston
(24 or 24, 25 and 26) be replaced as a set.
Composition seat discs (25) may be replaced
individually.
6. If a composition (soft) seat trim design is
utilized, use the following sub-steps:
a. Tighten the “fl ats” of the seat disc screw
(26) within a vise. Firmly hand-grip the
piston (24) and turn CCW to loosen the
seat disc screw (26). If too tight, place a
screwdriver or similar rod within the pis ton
(24) port holes and rotate. Remove the
piston (24), and inspect for raised burrs
around the port holes if a device is used
to loosen; de-burr as required. NOTE: Do
not grip the piston (24) with a wrench.
b. Remove the seat disc (25) and clean the
recessed piston (24) area where the seat
disc (25) is placed. If the edges which form
the recess of the piston (24) are worn, also
replace piston (24) and seat disc screw
(26).
c. Place seat disc (25) into recessed end of
piston (24).