lineshaft bearings of axial flow pumps are lubricated by either water or
oil, according to customer preference and water quality.
The initial-cost comparison between water and oil lubrication depends upon
the overall length of the pump. On long-column pumps, the oil
lubricated system tends to be lower priced, whereas water lubrication
costs less on short pumps.
Oil lubrication gives increased bearing life and is essential when grit or
suspended solids are to be pumped. Batescrew supply a suitable
biodegradable oil, which is drip-fed from above the pump.
The main shaft is enclosed within a steel lube-tube, which carries
multiple bronze bearings. The lube-tube is hot dip galvanised,
internally and externally, protecting the lubricant from contamination by
the products of condensate corrosion.
The lowest bearing, located beneath the impeller, is bronze and is grease
lubricated via a tube extending down from the pump mounting plate at the
Adjustable drip-feeders are fitted as standard.
Solenoid operated drippers are available for use with automatic
start systems, allowing lubrication to commence fifteen minutes prior to
starting the pump.
Clear sand-free potable water is necessary for water-lube.
Water lubricated pumps have stainless steel shafts running in EPDM rubber
bearings and are fitted with either packing glands or mechanical seals,
depending on the level of pressure to be expected in the discharge head.
Maximum spacing of the lineshaft bearings is limited to 1.22 metres,
ensuring that the design stress of the shaft is in compliance with
‘Fixed Fire Pump Standard AS2941'.
This often means ‘more bearings per pump on Batescrew pumps'.
are reversible, for extra wearing life.
Water-cooled Thrust Bearing.
Thrust bearings, located at the top of the drive column, are held in a
water-jacketed cast iron housing. Cooling water is tapped from the
pump discharge, circulates through the bearing housing and is returned to
the discharge line. If a pump has a long drive column extension (as
for underground discharge) and low operating head, there may be
insufficient pressure for cooling water to reach the thrust bearing.
In such cases a special air-cooled bearing assembly or a separate
thermosyphon cooling system may be specified.