8
4.7
ROTOR AXIAL CLEARANCE ADJUSTMENT
The Race Carrier when finally positioned determines the
Bracket Ball Bearing location within the Bracket. As the
Ball Bearing is positively locked to the Shaft shoulder by
the Spacer sleeve and coupling, the positioning of the
Ball Bearing will control the Rotor axial clearance.
To adjust axial clearance:
a) A crank handle or other suitable arrangement
should be affixed on the coupling end of the
Rotor/Shaft assembly to facilitate rotating of the
assembly by hand.
b) Screw Race Carrier in a clockwise direction
whilst simultaneously rotating assembly. This
enables sensing the rotor-cover point of contact
ie. a slight drag is felt by hand.
c) Mark Race Carrier position relative to Bracket i.e.
establish a datum point for setting axial
clearance.
d) Back off Race Carrier 180 degrees to eliminate
any backlash.
e) Retighten Race Carrier to a point measured
radially from the previously marked datum equal
to the amount of desired axial clearance.
Note:
For models MD100, MD114, MD112, MD200 &
MD212 2.99mm radial movement on the O.D. of the
Race Carrier equals 0.025 mm axial movement of the
Rotor/Shaft assembly. Refer Table of Clearances for
actual clearances.
Example: Std 'A' clearance for MD212 – 0.06-0.10 mm
(0.06
÷
0.025) x 2.99 = 7.18
(0.10
÷
0.025) x 2.99 = 11.96
is equivalent to 7-12mm radial movement on the outside
diameter of the Race Carrier.
f) At this point, check for freedom of rotation of
assembly. Axial clearance should now be
established.
g) Tighten Grubscrew locking Race Carrier to
Bracket.
SECTION 5 - INTEGRAL BYPASS VALVES
5.1 GENERA
L
This Bypass Valve (BPV) is intended for integral
installation in EBSRAY's Internal Gear Pumps. The valve
is mounted in such a manner as to return liquid from the
discharge side of the pump to the inlet side of the pump
when differential pressure reaches or exceeds a preset
level.
The BPV is mounted with the Adjusting Screw pointing
toward the inlet chamber of the pump.
5.2 OPERATION
The BPV is spring loaded and adjustable within a
pressure range determined by the actual spring used.
EBSRAY can supply a variety of springs to suit varying
differential pressures. They are designed for liquid
service and to provide pump and drive protection from
excessive differential pressures above specified duty
point parameters.
Upon commissioning, the BPV should be adjusted in
accordance with the predetermined pump differential
pressure required.
5.3 MAINTENANCE
Apart from BPV Housing replacement, other
maintenance tasks and inspections can be carried out
with the BPV fixed to the pump Cover, so long as
complete isolation, depressurising and purging have
been completed.
5.4 DISASSEMBLY
1.
Remove Adjusting Screw Cap.
2. Unlock Adjusting Screw Locknut. and release
spring tension by unscrewing Adjusting Screw.
3.
Unscrew BPV Housing Cap and remove internal
components noting order of assembly.
5.5 INSPECTION
1.
Inspect all components for damage or excessive
wear.
2.
Repair or replace as required.
5.6 REASSEMBLY
(Refer Drawing – Section 7)
Note:
Ebsray recommends the replacement of gaskets
during every overhaul.
1.
Lap valve into valve seat. . Ensure no lapping
compound remains, as this may damage pump.
2. Screw Locknut onto Adjusting Screw and then
screw Adjusting Screw fully into BPV Cap
3. Fit Valve into Housing, ensuring freedom of
movement.
Note:
To maintain assembly stack and reduce spring
tension, back off the Adjusting Screw while tightening the
BPV Cap.
....Poppet type valve as fitted to MD100 & MD114:
3.
Fit Spring onto top of Valve.
4.
Fit Spring Cap to Spring.
5.
Fit Gasket to BPV Housing Cap and screw BPV
Cap onto BPV Housing ensuring that the Adjusting
Screw locates in the hole in the Spring Cap.
....Balanced type as fitted to MD112, MD200 & MD212:
1.
Ensure bleed holes in Valve and Pressure Pin are
unobstructed.
2.
Assemble Pressure Pin, Spring Retaining Washers
and Spring.
3.
Fit Gasket to BPV Housing Cap and screw BPV
Cap onto BPV Housing engaging the Pressure Pin
into Adjusting Screw.
Summary of Contents for MD Series
Page 12: ...12 NOTES...
