Fixed Flow
Dismantling and Assembly
Before removing and dismantling the pump, check flow and
pressure. If either of these are low the pump must be
changed. Renewal of components such as gears, bearings
and housing will not effect a permanent cure. If the pump
output is satisfactory but there is external leakage, the pump
should be removed and dismantled for re-sealing only.
Before removing and dismantling the pump, make sure the
exterior of the pump and working area is thoroughly cleaned
and free of possible sources of contamination.
Dismantling
1
Remove the four bolts
3
and serrated washers
4
which
clamp the units together.
2
Use a soft faced hammer to separate front body
5
and
rear body
6
after first marking them to ensure correct
re-assembly.
3
Remove splined coupling
7
and O-rings
8
. Discard the
O-rings.
4
Use a soft faced hammer to separate end cover
9
from
rear body
6
, after first marking them to ensure correct
re-assembly.
5
Remove drive gear
10
from its bore. Pushing it out of
t he rear b od y w ill also rem ove b alanc e p lat e
11
complete with seal
12
and seal energiser
13
. Discard
the seal and seal energiser. Note the position of the
driveshaft and the balance plate to ensure correct re-
assembly.
6
Remove driven gear
14,
followed by balance plate
15
complete with seal
16
and seal energiser
17
. Discard
the seal and seal energiser.
7
Discard O-ring
18.
8
Use a soft hammer to separate mounting flange
19
from
front body
5
, after first marking them to ensure correct
re-assembly.
9
Remove circlip
21
and shaft seals
22.
Note which way
round the seal lips are fitted to ensure correct fitting of
new seals on re-assembly.
10
Remove driveshaft
23
from front body
5
. Removal will
also remove balance plate
28
complete with seal
29
and
seal energiser
30
. Discard the seal and seal energiser.
11
Remove driven gear
27
followed by balance plate
24
,
seal
25
and seal energiser
26.
Discard the seal and seal
energiser.
12
Discard O-ring
31
.
13
Remove all sealant from the contact faces of the
mounting flange/front body and end cover/rear body
interfaces.
14
Wash all components and immediately apply a coating
of hydraulic oil to prevent corrosion.
Inspection
1
Generally check all pump parts for damage and/or
wear. The O- ring grooves, the seal recess in the
mounting flange and all sealing faces must be free of
burrs and scores which could result in seal damage
and hence hydraulic oil leakage.
2
Renew the pump if any of the following symptoms
exist:
a
The PTFE coated bearings in the pump bodies, the
mount ing flange and t he end c over are w orn
through to reveal the bronze backing.
b
The g ear sid e f ac es are sc o red . Of t en
contaminated fluid results in a distinct wear step
coincident with the gear root diameter. This can
normally be felt by drawing a sharp point across
the gear side face from the journal towards the tip
of the gear.
c
There is a noticeable wear groove on driveshaft
23
where seals
22
run.
d
The balance plate faces are scored, particularly in
the area adjacent to the gear root diameter.
e
The shaft splines are worn or severely fretted.
f
The gear "cut-in" area in the low pressure side of
the pump body is deeper than 0.15 mm (0.006 in)
or has a torn or pitted appearance.
31 - 2
Section E
9803/3280
Section E
31 - 2
Issue 1
Main Pump
