Gorman-Rupp Pumps 14C20-4024T 1303140 and up - Manual (Page 36)

10 SERIES OM−05781
MAINTENANCE & REPAIR PAGE E − 14
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 adjusting
shims (76) 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 (0,5 to1,0 mm) be-
tween the impeller and the seal plate is necessary
for maximum pump efficiency. Measure this clear-
ance, and add or remove impeller adjusting shims
as required.
NOTE
If the pump has been completely disassembled, it
is recommended that the wear plate (41) and back
cover assembly (49) be reinstalled at this point. The
back cover and wear plate must be in place to ad-
just the impeller face clearance.
Install the same thickness of pump casing gaskets
(40) as previously removed. Secure the pump cas-
ing to the intermediate with the nuts (39). Do not
fully tighten the nuts until the impeller face clear-
ance has been set.
A clearance of .010 to .020 inch (0,25 to 0,50 mm)
between the impeller and the wear plate is also rec-
ommended for maximum pump efficiency. This
clearance must be set after installing the back
cover, by adding or removing gaskets in the pump
casing gasket set until the impeller scrapes against
the wear plate when the shaft is turned by hand. Af-
ter the impeller scrapes, add approximately .010
inch (0,25 mm) of gaskets.
NOTE
An alternate method of adjusting this clearance is to
reach through the discharge port with a feeler
gauge and measure the gap. Add or subtract pump
casing gaskets accordingly.
If a lifting eye was used to move the pump casing,
be sure to remove the lifting eye from the pump
casing.
Do not attempt to lift the complete pump
unit using the lifting eye. It is designed
to facilitate removal or installation of in-
dividual components only. Additional
weight may result in damage to the
pump or failure of the eye bolt.
Suction Check Valve Installation
(Figure E−2)
Inspect the check valve assembly (58) 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 (64).
NOTE
If the suction flange was removed, replace the gas-
ket (65), and apply ‘Permatex Aviation No. 3 Form-
A-Gasket’ or equivalent compound to the mating
surfaces.
Back Cover Installation
(Figure E−2)
If the wear plate (42) was removed for replace-
ment, carefully center it on the back cover and se-
cure it with the hardware (44 and 45). The wear