Gorman-Rupp Pumps 14C20-B 740693 and up - Manual (Page 33)

10 SERIES OM-00680
MAINTENANCE & REPAIR PAGE E - 10
Impeller Installation and Adjustment
Inspect the impeller, and replace it if cracked or
badly worn.
The shaft and impeller threads must be
completely clean before reinstalling the im­
peller. Even the slightest amount of dirt on
the threads can cause the impeller to seize
to the shaft, making future removal difficult
or impossible without damage to the im­
peller or shaft.
Install the same thickness of impeller shims (71) as
previously removed and screw the impeller onto
the shaft until tight.
NOTE
At the slightest sign of binding, immediately back
the impeller off, and check the threads for dirt. Do
not try to force the impeller onto the shaft.
A clearance of .020 to .040 inch (0,51 to 1,02 mm)
between the impeller and the seal plate is neces­
sary for maximum pump efficiency. Measure this
clearance and add or remove impeller shims until
this clearance is reached.
NOTE
Be sure the seal plate is tight against the pedestal
while measuring this clearance.
Install the bottle oiler and piping (72, 73 and 74).
Pump Casing Installation
Remove the hardware temporarily securing the
seal plate to the pedestal. Install the same thick­
ness of pump casing gaskets (26) as previously re­
moved and secure the pump casing (1) to the seal
plate and pedestal with the nuts (24). Do not fully
tighten the nuts at this time.
NOTE
The back cover assembly must be in place to adjust
the impeller face clearance.
A clearance of .010 to .020 inch (0,25 to 0,51 mm)
between the impeller and the wear plate (27) is also
recommended for maximum pump efficiency. Set
this clearance by adding or removing gaskets in
the pump casing gasket set (26) until the impeller
scrapes against the wear plate when the shaft is
turned by hand. After the impeller scrapes, add ap­
proximately .010 inch (0,25 mm) of gaskets.
After the face clearance has been set, tighten the
nuts (24) securing the pump casing to the pedes­
tal.
Suction Check Valve Installation
Inspect the check valve assembly (43) and replace
it if badly worn.
NOTE
The check valve assembly must be replaced as a
complete unit. Individual parts are not sold sepa­
rately.
Reach through the back cover opening with the as­
sembled check valve, and position the check valve
adaptor in the mounting slot in the suction flange.
Align the adaptor with the flange hole and secure
the assembly with the check valve pin (52).
NOTE
If the suction flange was removed, replace the gas­
ket (64), and apply `Permatex Aviation No. 3 Form‐
A‐Gasket' or equivalent compound to the mating
surfaces.
Back Cover Installation
If the wear plate (27) was removed for replace­
ment, secure it to the cover plate (35) using the at­
taching hardware (29 and 30) at this time. The wear
plate must be concentric to prevent binding when
the back cover is installed.
Clean any scale or debris from the contacting sur­
faces on the pump casing that might prevent a
good seal with the back cover. Replace the back
cover gasket (39) and slide the back cover assem­
bly into the pump casing. Be sure the wear plate
does not bind against the impeller.