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AND PRE-LOAD)
•
Align the rotors in the rotor case as per Figure
30
•
Check the rotor to rotor meshing clearance (d
in Figure 30, left of bottom lobe) on the first
lobe and note it down.
•
Turn the rotors 120° (clockwise on driving
shaft rotor) and take the rotor to rotor
meshing clearance (d in Figure 30, left of
bottom lobe) on the second lobe and note it
down.
•
Turn the rotors 120° (clockwise on the driving
shaft rotor) and take the rotor to the rotor
meshing clearance (d in Figure 30, left of
bottom lobe) on the final lobe and note it
down.
•
Turn the rotors 60° (clockwise on driving
shaft rotor) and check the rotor to rotor
meshing clearance (now on the right of
bottom lobe) and note it down.
•
Turn the rotors 120° (clockwise on the driving
shaft rotor) and take the rotor to the rotor
meshing clearance (On the right of bottom
lobe) on the second lobe and note it down.
•
Turn the rotors 120° (clockwise on the driving
shaft rotor) and take the rotor to rotor
meshing clearance (On the right of the
bottom lobe) on the final lobe and note it
down.
•
This will give you the meshing clearance of all
lobes.
•
Mesh Clearances of Left and Right of Lobes
are shown in Table 7.
•
To obtain the correct meshing clearance of
the lobes, shims (30a) need to be added or
removed in front of a gear.
o To increase the gap on the left hand
side of the lobes add shims to the
driving shaft or remove shims from the
driven shaft.
o To decrease the gap on the left hand
side of the lobes remove shims from
the driving shaft or add shims to the
driven shaft.
o To
move
0.025mm you need to add or remove
approximately 0.075mm of shim to the
gears.
For Spot Checking Rotors that have Run:
•
Note down all meshing clearances as shown
above for re-fitting or new rotors.
•
Check the rotor to rotor meshing clearances
are between the values shown in the Mesh
the
meshing
clearance
setup columns in Table 6.
•
If the values are not within the limits remove
the rotors and re-fit using the procedure
stated in the section For Re-fitting or New
Rotors.
6.9 END COVER RELIEF VALVE
Refer to chapter 8 EXPLODED DIAGRAMS
ATTENTION
New relief valves are not supplied factory set.
This pressure setting should be done when the
valve is fitted to the pump. (See 3.13 END COVER
RELIEF VALVE)
•
Remove the relief valve end cover assembly
from the pump. Before doing so make a note
of the position of the 'Direction of Flow' arrow.
•
Remove the adjusting screw (135).
•
Hook the spring (132) out from the top of the
housing (133). Alternatively turn the valve
upside down and tip the spring out.
•
Remove the 2 screws (136) and remove the
housing (133).
•
The valve seat (128) and diaphragm (129) will
come off of the end cover (125) together with
the housing. To disassemble these, tap the
end of the guide pin (134) with a soft tool.
The valve seat, diaphragm and piston/guide
pin assembly should now separate from the
housing.
•
Remove the O-ring (126) from the groove in
the valve seat.
Inspection:
•
Inspect the condition of the diaphragm.
Look for splits, cracks or other signs of wear
and fatigue. Replace if necessary.
•
Inspect the conical end of the piston (131)
around the screw thread and around the
outside edge of the cone to ensure there are
no sharp edges or burrs.
Refer to chapter 8 EXPLODED DIAGRAMS
Re-Fitting:
•
Lay the end cover (125) on its face.
On a clean surface, taking great care not to
scratch the internal face
•
Fit the O-ring (126) into the groove in the
face of the valve seat (128). Use a suitable
grease to 'stick' the O-ring in the groove.
•
Turn the valve seat upside down and place
32
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