Flowserve Gearex Rotary Gear Pumps External and Internal Bearing - Manual (Page 41)

EXTERNAL GEAREX USER INSTRUCTIONS ENGLISH 71569246 (2167B-E1)
Flowserve Pump Division 41
®
gears. Slide the shaft assembly into the body (1)
and remove the timing gears and keys.
f) If rotor spacers are required, slide them onto the
shafts and up against each end of the rotors.
g) Install the thrust bearings (16) in the rear bearing
housing and retain with snap ring (25).
h) Mount a new end flange gasket (50) on the rear of
the body.
i) Slide the rear bearing housing assembly over the
shafts and mount on the end of the body. (Note
that the “top” mark is in the correct location. If a
new rotating element is being installed in the
pump, refer to section 6.10.1.2 Internal bearing
pump.
j) Re-install the timing gear spac ers (18), keys (22),
timing gears (13) and locknuts (19) and washers
(20) as indicated by the marking done during
disassembly. Tighten the locknuts snugly but
avoid overtightening as the lockwasher anti-
rotation tab could be damaged. Bend one
lockwasher tang on each lockwasher to lock the
nuts.
k) Withdraw the rear bearing housing and shaft
assembly slightly from the body and check the
end clearance of the rotor/rotor spacer and the
bearing housing face. This should be equal to
half the clearance listed in the Table of
Engineering Data in this manual. If the measured
clearance varies from the value listed by more
than 25 per cent, it will be necessary to dismantle
the unit and adjust the position of the rotors in the
press. Failure to provide the correct clearance
may result in pump seizure (clearances too tight)
or poor hydraulic performance (clearance too
large).
l) Mount a new gasket (50) on the rear bearing
housing (3) and fit the rear cover (4). Replace all
capscrews in the rear end finger tight only.
m) Install the front bearing outer race assemblies (14)
into the front bearing housing (2).
n) Mount a new gasket (50) on the front of the body
(1) and slide the front bearing housing into place,
noting the position of the “top” mark.
o) If the pump is fitted with a mechanical seal, mount
the rotating head on the drive shaft using the mark
scribed at disassembly for location. Tighten all
set screws securely.
p) Mount a new gasket (50) on the front of the
bearing housing and install the front head (5).
Install all capscrews finger tight.
q) Re-fit all alignment dowel pins (60).
r) Tighten all capscrews at rear end of pump.
s) While tightening all capscrews at the front of the
pump, rotate the drive shaft by hand to check for
binding. If the pump binds before the capscrews
are tight, it will be necessary to install another
gasket between the front bearing housing and
body.
t) Install the seal stationary seat in the seal gland
and install the gland on the front head.
u) If the pump has a packed stuffing box, install new
packing and replace gland.
6.10 New rotating elements
6.10.1 Mechanical seal fitted pumps
6.10.1.1 External bearing pump
If a new rotating element is being installed, the pump
should be assembled without mechanical seals up to
and including step I) in section 6.9.1 or 6.9.2. The
following procedure is then to be followed.
a) Using a straightedge, mark the point on the drive
and driven shafts in line with the flange face on
the front end of the body.
b) Remove the thrust bearing bracket to body
capscrews and nuts, and pull the rotating element
partially out from the rear of the pump with the
rear bracket assembly intact.
c) Using a straightedge, mark the point on the shafts
in line with the flange face of the rear bracket.
d) Remove the bracket assembly from the rotating
element.
e) With the datum lines now marked on the shafts,
refer to the applicable mechanical seal drawing for
the required setting dimension.
f) Assemble the seals on the shafts and proceed
with the steps outlined in section 6.9.1 or 6.9.2.
6.10.1.2 Internal bearing pump
If a new rotating element is being installed, the pump
should be assembled without mechanical seals up to
and including step I) in section 6.9.3. The following
procedure is then to be followed.
a) Using a straightedge, mark the point on the drive
shaft in line with the flange face on the front head.
b) Remove the front head.
c) With the datum lines now marked on the shafts,
refer to the applicable mechanical seal drawing for
the required setting dimension.
d) Assemble the seals on the shafts and proceed
with the steps outlined in section 6.9.3.
6.11 Free movement
If the pump does not turn freely after reassembly, the
following procedure should be observed.
a) Remove front and rear head dowel pins.
b) Loosen all head to body capscrews except for the
four corners at each end.
c) Check location of rotors in the body bores by
reaching into the discharge flange and checking