Gorman-Rupp Pumps U4B65S-B 1298951 and up - Manual (Page 37)

OM-05667 SUPER U SERIES
MAINTENANCE & REPAIR PAGE E - 13
Back Cover Installation
(Figure 1)
If the wear plate (14) was removed for replace­
ment, install a new O‐ring (16) in the groove in the
wear plate. Carefully center the wear plate on the
back cover and secure it with the hardware (17 and
18). The wear plate must be concentric to prevent
binding when the back cover is installed.
The clearance between the impeller and wear plate
is adjusted using four adjusting screws (25) and
locking collars (22). There are 18 detents on the
I.D. of each locking collar. Indexing the collars one
detent on the adjusting screws represents approxi­
mately .005 inch (0,13 mm) of wear plate clear­
ance. The recommended clearance between the
wear plate and the impeller is .003 to .005 inch
(0,07 to 0,12 mm).
USE TWO
OPPOSING
HAND NUTS
TO PRESS
BACK COVER
INTO PUMP
CASING
USE TWO REMAINING
ADJUSTING SCREWS
AND LOCKING COL­
LARS TO SET FACE
CLEARANCE
INDEX COLLARS 3
DETENTS COUNTER‐
CLOCKWISE, THEN
TURN CLOCKWISE
UNTIL SCREW
HOLES ALIGN
Figure 6. Installing and Adjusting Back Cover
Replace the back cover and wear plate O‐rings (15
and 19) and lubricate them with a generous
amount of No. 2 grease. Clean any scale or debris
from the contacting surfaces in the pump casing
that might interfere or prevent a good seal with the
back cover.
Screw the four adjusting screws (25) into the
tapped holes in the back cover plate until they are
just flush with the machined surface on the back
side of the cover plate.
Align the back cover plate over the studs (23) and
slide it into the pump casing. Use two back cover
nuts (24) on diagonally opposing studs to press
the back cover into the pump casing until the wear
plate just touches the impeller when the shaft is
turned by hand. Tighten the back cover nuts
evenly to avoid binding.
With the wear plate just touching the impeller, turn
the two free adjusting screws until they engage the
pump casing. Position the locking collars over the
adjusting screws so the holes in the collars for the
locking screws align approximately with the holes
in the cover plate.
Loosen the back cover nuts used to press the back
cover into the pump casing one full turn.
Pull the collars off the adjusting screws, index them
one detent counterclockwise, and reinstall the col­
lars on the adjusting screws. Use the collars to turn
the adjusting screws clockwise until the holes in
the locking collars realign with the tapped screw
holes in the back cover plate. Secure the locking
collars to the back cover plate with the hardware
(20 and 21). Install the two remaining back cover
nuts snugly against the adjusting screws.
Remove the first two back cover nuts from their
studs. Turn the adjusting screws clockwise until
they engage the pump casing. Install the locking
collars and hardware (20 and 21). Reinstall the
back cover nuts.
Be sure the wear plate does not scrape against the
impeller.
Over time it may be necessary to repeat the adjust­
ment process to compensate for normal wear be­
tween the impeller and wear plate. When all of the
adjustment has been used on the back cover side
of the pump, an additional 0.125 inch (3,2 mm) of
adjustment may be obtained by removing the ro­
tating assembly adjusting shims (12).
Allow an installed pump to completely cool before
draining liquid from the pump casing. Remove the
back cover. Remove the rotating assembly adjust­
ing shims, then reinstall the hardware securing the
rotating assembly to the pump casing. Perform the
back cover adjustment procedure described
above to obtain the proper face clearance.