Seven thrust bearing assemblies are available, matching
pump power ratings from 18 kW (25hp) to 740 kW (992hp).
These units are fitted to both Axial Flow and Turbine pumps, The
smallest bearing, No.1, is air cooled, while all larger sizes have water cooled housings,
for which pressurised cooling water is tapped from and recirculated to the discharge head.
Sizes, power ratings and replacement parts are listed in the table at the foot of this page.
This photo represents thrust bearing sizes 2,3,4,5 & 6.
(The heavy duty model, size 6, has two tapered roller bearings, some models contain three or four bearings in tandem, as indicated in the table.)
A pump shaft, not shown, passes up through the Bearing Carrier, where a single drive key engages keyways in the shaft, the carrier and the drive coupling (or pulley).
The protruding upper end of of the pump shaft is threaded for a Top Nut, which transfers pump thrust down onto the carrier and thence to the lower bearing.
The top bearing supports radial loads from pulleys, drive shafts etcetera.
|Smallest in the range, No. 1 Thrust Bearing, is air cooled, with two MFCG type bearings in a cast iron housing. It has a similar bearing carrier to that seen above, distributing thrust to both bearings.|
|SIZE SELECTION is determined by power rating of the pump, see table below.|
|HOUSING IDENTIFICATION An existing thrust housing may be identified by reference to shaft size, as listed in the table. Housings 4 & 5, which share a common shaft size, have bearing model stamped next to the grease nipple or on the end face of the Bearing Carrier.|
Bearings should be greased with Shell Alvania EP2, or equivalent.
No. 1 Thrust Bearing: Apply one pump form a grease gun, to each of the two MFCG bearings, per month for continuous running or one pump every three months for intermittent running.
Bearings 2,3,4,5, 6, 7; in constant use: Apply two pumps from a grease gun, to the single nipple at top of the housing, every month.
Bearings 2,3,4,5, 6, 7; intermittent use: Apply two pumps every three months.
BEARING LIFE WILL BE SHORTENED by over greasing, indicated
by excessive accumulation of grease and dust beyond the seals.
REPACKING BEARINGS After replacing bearings and seals (water cooled housings), fully re-pack each bearing with grease and fill one-third of the cavity between the bearings.
ABOVE FLOOD LEVEL Standard thrust bearings must always be kept above flood
level. When a discharge head is
to be located below flood level, an extended drive column will allow motor
and thrust bearing to be kept above high water. This applies to
both vertical and angle application pumps.
If there will be insufficient pressure for cooling water to reach an elevated housing, a special air-cooled housing or a separate thermo-siphon water cooling system should be used. Please consult Batescrew Technical Services Department for details.
|SPECIAL SUBMERSIBLE HOUSINGS Special housings, with mechanical seals, are made to order, for applications such as fully submerged, hydraulically driven pumps.|
CONSTRUCTION Standard housings, sizes 1, 2& 3, are of Cast Iron;
sizes 4, 5& 6, are Mild Steel fabrications. Bronze castings or Stainless Steel fabrications may be specified for water cooled housings used in marine or corrosive applications.
|DISMANTLING from PUMP|
locking screw from Top Nut.
2) Remove Top Nut and Drive Key
3) Remove flange bolts. (The entire bearing assembly can now be 'jacked off', if it is found to be frozen to the pump shaft.)
4) To remove a frozen housing, rotate it beyond the bolt holes, then screw over-size bolts into the threaded flange holes (indicated in photo above), jacking against the top of the discharge head or other mounting flange.
5) After removing the top Cover Plate, the two bearings and carrier may be pushed out of the housing, by screwing bolts into two threaded holes in the bottom of the housing. (These holes are plugged with Allen screws.)
|TOP NUT ADJUSTMENT|
|As well as
transferring thrust to the Bearing Carrier, the Top Nut raises or lowers
the pump shaft and impellers. Incorrect clearance above or below
impellers may result in loss of performance, overloading, seizing or serious damage.
Two entirely different methods are used for setting impeller height, via the Top Nut, depending on the type of pump - Axial Flow or Turbine.
1) AXIAL FLOW PUMPS Gently screw the Top Nut down, to the limit of its travel (raising impellers to the top of their housings), then back-off the nut two full turns. Lock the Top Nut by means of the grub screw, in whichever of the two tapped holes in the nut is closest to the keyway, slightly adjusting nut position so that the grub screw is seated in the bottom of the keyway.
2) TURBINE PUMPS The
vertical position of turbine impellers is more critical, requiring
impellers to be raised a specified distance from their lowest position
(Top Nut screwed clear of Bearing Carrier).
|Model||Power||Shaft Size||Top Bearing||Bottom Bearing||Seals|
|1||18.7 kW (25hp)||31.75mm||1.25in||1.75in MFCG||1.75in MFCG||n/a|
|2||44.8 kW (60hp)||38.1mm||1.5in||4310||7310||TC50728 (2 only)|
|3||93.3 kW (125hp)||44.45mm||1.75in||4312||7312||TC60808 (2 only)|
|4||139.3 kW (250hp)||50.8mm||2in||6315 (2 only)||7315||TC75951 (2 only)|
|5||298.6 kW (400hp)||50.8mm||2in||6315 (2 only)||7315 (2 only)||TC75951 (2 only)|
|6||447.9 kW (600hp)||69.85mm||2.75in|| Cup
|6"x5"x0.5" (2 only)|