Gorman-Rupp Pumps PA6F60-4045T 1521221 and up - Manual (Page 42)

PA SERIES OM-06189
MAINTENANCE & REPAIR PAGE E - 20
peller lock screw). Make sure the seal spring
seats squarely over the step on the back side of the
impeller.
When installing the impeller, the capscrew
must be long enough to enter the shaft at
least eight full threads. Otherwise, damage
to the shaft threads may occur.
Shaft
Key
Pipe
Washers
Long
Capscrew
Figure 9. Installing Impeller
A clearance of approximately .030 inch (0,76 mm)
between the impeller and the back plate is recom­
mended for maximum pump efficiency. Measure
this clearance, and add or remove impeller adjust­
ing shims as required.
The pump casing must be installed in order to
properly torque the impeller lock screw (50). After
the impeller clearance has been set, install the
pump casing as described below, then proceed as
follows to install the impeller washer (51) and lock
screw.
NOTE
To ensure proper torquing of the impeller lock
screw, make sure the tapped hole in the impeller,
the impeller washer and the impeller lock screw are
clean and dry (it is not necessary to remove the pro­
tective coating from the capscrew). It is recom­
mended that a new impeller lock screw be used
whenever the impeller is removed. To ensure the
proper lock screw material and specifications, use
only genuine Gorman‐Rupp replacement parts.
With the pump casing installed, coat the threads of
a new impeller lock screw with “Loctite Threadlock­
er No. 262” or equivalent compound, and install
the impeller washer and lock screw. Immobilize the
impeller by inserting a wood block through the dis­
charge opening or cleanout cover opening as de­
scribed in Pump Casing And Wear Ring Remov­
al. With the impeller immobilized, torque the impel­
ler lock screw to the specifications shown in Table
E-1.
Table E-1. Impeller Lock Screw Torque Values
Screw Size Torque
(UNC) Ft. Lbs. (M. Kg.)
.38-16 20 (2,8)
.50-13 40 (5,5)
.62-11 90 (12,4)
.75-10 135 (18,7)
1.00-8 265 (36,6)
1.12-7 360 (49,8)
1.25-7 510 (70,5)
1.50-6 875 (121,0)
Wear Ring And Pump Casing Installation
(Figure 5)
If the wear ring (49) was removed, chill the wear
ring by refrigeration and press it into the volute
bore until fully seated.
The wear ring must seat squarely in the
pump casing; otherwise binding and/or
excessive wear will occur.
Install the casing gasket (5). Use a suitable hoist
and sling to position the casing over the impeller,
and secure it to the back plate with the hardware
(42, 43 and 44).