Operation and maintenance manual

Braking System - Triple Pump
Section 250-0040
SM 2157 8-02
4
foreign matter.
FAILURE MODES
It is not recommended giving the triple gear pump a
major overhaul, however replacement seal kits are
available. Typical failure modes of triple pump are
illustrated in table below.
SPECIAL TOOLS
There are no special tools required for procedures
outlined in this section. Refer to Section 300-0070,
SERVICE TOOLS, for part numbers of general service
tools required. These tools are available from your
dealer.
PART TYPE OF WEAR WEAR CAUSES MATING COMPONENT
DEFECT
Shaft seal Lip wear external leakage. - External contamination Grooving of driveshaft.
- High oil temperature
- Overspeeding
- High inlet pressure
Wearplates Scoring/burning of faces - Oil contamination Scoring or abrasive wear
adjacent to gear - low - Cavitation of gear side faces.
volumetric efficiency. - Starting pump dry
- Running pump in reverse
Wearplate back-up Extrusion/melting of back-up - - Over pressurisation This type of failure is likely
seal low volumetric efficiency. - High oil temperature to be accompanied by
- Cavitation severe damage to wearplates
gears and bearing.
Wearplate seal Extrusion/seal failure - low - Over pressurisation Damage to wearplate and
volumetric efficiency. - Excessive pressure cycle backup seal may also occur
- Running pump in reverse with this type of fault.
Bearings Smooth even wear with a - Long service life Gear journals are likely to
tendancy for bearing surface - Working for high show even polishing with
to change colour from grey to percentage of duty cycle light scoring due to
bronze, indicating that the close to peak pressure contamination passing
PTFE overlay is wearing rating intermittently through the
through - the bearing is coming - High oil temperature bearings. Replace pump
to end of its useful life. - Low oil viscosity section.
Bearings Total bearing failure with - Oil contamination Usually results in severe
heavy scoring, overheating - Over pressurisation damage to all the major
and possible bearing meltdown. - High oil temperature pump components. Pump is
- Oil starvation almost certainly beyond
- Low viscosity or grade economic repair.
- Inferior oil quality
- Cavitation
- Running pump in reverse
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