A Project on Pressure and temperature analysis of tilted pad thrust bearing using Teflon pads
“PRESSURE AND TEMPERATURE ANALYSIS OF
TILTED PAD THRUST BEARING WITH THE USE OF
TEFLON AS PAD MATERIAL”
Presented by Group No.07
DUDHANE SWAPNIL BHAIRAVNATH (2011BME015)
KABADAGI RAHUL SHIVKUMAR (2011BME024)
MANGURE AZHAR AYUB (2011BME035)
PATEL JUNED YUNUS (2011BME039)
CHAVAN KARANSINH JITENDRA (2012BME202)
The term Sliding bearing refers to a type of bearing where two conformal surfaces
usually the stationary bearing and a moving shaft slide relative to one another with load
distributed directly across the interface. A suitable lubricant may be employed to reduce
the friction between these two surfaces. In fluid film bearings, this lubricant builds up a
layer of sufficient thickness such that the two surfaces are completely separated.
Tilted Pad Thrust Bearing are designed to transfer high axial load from rotating shaft
with minimum power loss. Bearing consist of circumferential pads & each pad is free to
tilt to create self lubricating hydrodynamic film .
The number of parameters which affect the bearing are categorized as operating
parameter and performance parameters.
Speed of rotation, applied load, surface curvature & type of lubrication are the operating
parameter while max. pressure generated ,temperature of bearing , oil viscosity
,minimum film thickness, surface wear are performance parameters.
Tilting pad thrust bearing is an assembly of number of tilted pads, Runner, lubricating
oil, cooling coils and casing.
Bearing pads are individual plates which are free to tilt about their individual pivots.
usually three or more pads are used .
Pads are made up of two layers of materials .Face layer of pad is Babbit or PTFE
(Polytetrafluoroethylene) with 2- 3 mm thickness. This layer is supported by MS pad
called as backing.
Lubricating oil is provided in housing as a bath or fed either to centre of housing near
shaft or to the leading edge of pad with external aid.
Depending upon the method of lubrication, it is also differentiated as Flooded
lubrication or Directed lubrication.
Runner of bearing is attached to rotating shaft whose thrust need to support by bearing.
In Titling pad thrust bearing, Runner and pads are separated by an oil film during
When the runner is stationary ,the pads are in direct contact with pad .As shaft with
runner rotates form an oil film between the pad and runner.
Each Pad will tilt to the some angle which forms converging wedge. The flow
constriction due to wedge acts as a bottleneck, which causes slowing down the flow
rate across the pad from the inlet edge towards the trailing edge.
The gradual reduction of oil volume in the gap leads to rise in pressure of the oil film
which lifts the shaft.
To acquire detailed understanding of the current system.
To modify old cooling system.
To replace lubricating Oil in the test Rig
To replace defective Direction Control Valve
To develop pressure sensor for pressure measurement
To develop temperature sensor for temperature measurement
To demonstrate the test rig for sake of pressure and temperature readings with
different load conditions
To measure frictional power losses
To analyze the obtained readings
To conclude on the basis of observations and readings taken.
DESCRIPTION OF TEST RIG:
It mainly consists of four distinct parts:
1) Driving motor along with driving pulley :
A.C induction motor.
Capacity 7.5 HP
Rated speed 1430 rpm
2) Oil Sump and Runner along with Driven Pulley:
Oil sump is a casting body . Inside this a pocket is fitted. Pocket has eight
equally placed radial slots and dowel pins. There are eight pads which tilt about an axis
passing through its geometric center along a radial slot.
Tilting of each pad about the pivot causes formation of wedge shaped oil
film along the sliding direction of runner. This wedge shape oil film in turn causes self
acting pumping action of oil. The combination of squeeze, stretch and wedge effect
generates pressure within oil film. Due to this pressure, load of runner is sustained.
3) Hydraulic power pack and loading system:
Loading system consists of lever, loading piece, brackets, with their base plate.
Hydraulic cylinder which is mounted on loading frame provides the load as per
requirement through loading lever beam. Loading frame consists of two vertical I
columns with four I beams welded together. Loading member is supported in brackets at
one end and loaded by hydraulic cylinder at other end.
4) Cooling System :
Copper tubing of 1 inch diameter is provided. One end of this copper tubing is
connected to a reservoir of water and other end is drained.
The cooling effect is provided by circulating water around the oil sump. For better
and effective cooling, the rate of water flow is increased by placing reservoir tank at a
height of 10 feet from setup foundation.
DEVELOPMENTS IN CURRENT PROJECT SET-UP:
The following developments are done :
DC valve replacement.
Modified calibration fixture.
JUSTIFICATION FOR SELECTION OF PTFE AS PAD MATERIAL:
Available Grades :
15% Peek PTFE
15 To 25% Glass Filled PTFE
25 To 35% Carbon Filled PTFE
15% Graphite Filled PTFE
40 to 60% Bronzed Filled PTFE
5 to 15% Aluminum Oxide Filled PTFE
5 to 10% Stainless Steel Filled PTFE
5 to 10% Mica Filled PTFE
55% + 5% Bronzed + Molybdenum Disulphide Filled PTFE
15% + 5% Glass + MOS2 Filled PTFE
INHERENT TEFLON PROPERTIES:
PTFE against steel has one of the lowest coefficients of friction
The load bearing capacity of the PTFE sheet is in the range of 130-140Kg/sq.cm
The PV values are found to be in excess of 10,000
Pressure (P) is the load placed on a bearing assembly. Velocity (V) is the
surface speed at which an object, such as a shaft, moves. P-V is defined as the
combination effect of the pressure of the object and the velocity at which it
moves on the bearing surface.
Service temperatures of -250 to +250°C are possible.
CALIBRATION OF DIAPHARGMS:
The material of diaphragm is Brass. Strain gauges are stacked on diaphragm
and such a diaphragms are mounted in a fixture for pressure measurement.
Diaphragm specification – 2 mm thick and 16 mm dia.
Procedure Of Calibration :
1) The strain gauges to be used for calibration is fitted in a fixture and mounted
on dead weight calibration apparatus.
2) The strain gauge connecting wires are attached to strain guage indicator.
3) The pressure variation is done by varying the dead weights.
4) For different loads the indicator gives different reading and these
readings are noted down.
INSTRUMENTATION FOR EFFECTIVE
For effective temperature measurement, locations for mounting of temperature
sensors are very necessary.
It is found that following methods are used for temperature measurement
1) Temperature Grid.
2) T 50/75 or 75/75
3) Oil Film Tapping.
From the above methods mentioned, temperature grid method is used.
It gives variation of temperature over pad surface
It gives temperature grid on pad surface.
It is best for laboratory testing.
INSTRUMENTATION FOR EFFECTIVE PRESSURE
Pressure on pad varies along length and width of pad.
We are interested to know maximum pressure carried by pad.
According to previous studies following locations were chosen for pressure
edge of pad
Centre of bearing
1 Pp1 14.07 133.10
2 Pp2 38.20 120.5
3 Pp3 34.30 105.76
• Point 1 is near leading edge and at upper
side of pad
• Point 2 is near 75/75 location. Maximum
pressure varies nearby this point.
• Point 3 is near trailing edge and at lower
side of pad.
175 1055 1936 2641
29.1 29.57 30 30.1
34.1 36.8 39.8 42.4
5 7.23 9.8 12.3
32.4 33.2 30.7 30.9
38.5 41.6 41.7 44
6.1 8.4 11 13.1
RATE OF WATER
3.25 X 10-
3.25 X 10-
3.25 X 10-
3.25 X 10-
HEAT GAINED BY
0.68 0.98 1.33 1.67
By referring to graph no.1, it can be concluded that pressure
carried by pad increases as load on pad increases
By referring to graph no.2, it can be concluded that temperature
of pad increases as load on pad increases.
Maximum temperature of pad is observed at 75/75 location.
By referring to graph no.3, it can be concluded that frictional loss
increases as load on pad increases
Maximum pressure on pad is observed near 75/75 location.
Maximum pressure on pad is observed near to maximum
LEG trademark coined by KINGSBURY
LEG slim-line low profile bearings
Each pad equally loaded
Leveling plates on back of pad
Leveling plates located in carrier ring ensures equal loading.
Effects of different surface coatings on wear resistance of sector
shaped pads and bearing performance can be studied.
Use of various pivot position rather than central pivot and its
effect on performance.
Implementation of various pad materials and assuring their
Use of different lubricating oil. E.g. Bio-lubricants.
Use of different pad profiles can be implemented