ME 205: Tribology & Power Transmission...
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ME205 1 ME 205: Tribology & Power Transmission Elements Clutches Asanga Ratnaweera Dept of Mechanical Engineering 13 December 2006 Asanga Ratnaweera, Department of Mechanical Engineering 2 Clutches Cutch is a device to connect driving and driven shafts of a machine, where the driven shaft can be disconnected almost instantaneously from the driving shaft as desired by the operator or driver. Driving shaft Driven shaft Clutch
Transcript of ME 205: Tribology & Power Transmission...
ME205
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ME 205: Tribology & Power Transmission Elements
ClutchesAsanga Ratnaweera
Dept of Mechanical Engineering
13 December 2006 Asanga Ratnaweera, Department of Mechanical Engineering
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ClutchesCutch is a device to connect driving and driven shafts of a machine, where the driven shaft can be disconnected almost instantaneously from the driving shaft as desired by the operator or driver.
Driving shaft Driven shaft
Clutch
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Classification of clutchesClutches
Jaw Clutches Friction Clutches Hydraulic Clutches
Plate Clutches Cone Clutches Centrifugal Clutches
Single Plate
Multi-plate
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Single plate clutchFlywheel
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Single plate clutch
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Single plate clutchClutch plate
Torsional damper springs
Friction lining
Splined hub
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Single plate clutchPressure plate
Splined hub
Pressure plate
Release levers
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Single plate clutch
Collar bearingPlate clutch
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Recall- Flat Collar BearingsFrictional Torque
The total frictional torque T:Considering uniform pressure (for new bearing)
Considering uniform wear (for old bearing)
⎥⎦
⎤⎢⎣
⎡
−
−= 2
22
1
32
31
32
rrrr
WT µ
[ ]2121 rrWT += µ
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The total frictional torque T :Considering uniform pressure (for new bearing)
Considering uniform wear (for old bearing)
Single plate clutch
⎥⎦
⎤⎢⎣
⎡
−−
= 22
21
32
31
322
rrrrWT µ
[ ]21212 rrWT += µ
Cutch plate has two friction surfaces
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Single plate clutchThe total frictional torque T :
R – mean radiusn– number of friction surfaces
For uniform pressure (for new clutches)
For uniform wear (for old clutches)
WRnT µ=
[ ]2
21 rrR +=
⎥⎦
⎤⎢⎣
⎡
−−
= 22
21
32
31
32
rrrrR
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Multi-plate clutch
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Multi-plate clutch
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Multi-plate clutchThe total frictional torque T :
R – mean radiusn– number of friction surfacesn = n1+ n2-1where;n1 – number of discs on the driving shaft n2 – number of discs on the driven shaft
For uniform pressure (for new clutches)
For uniform wear (for old clutches)
WRnT µ=
[ ]2
21 rrR +=
⎥⎦
⎤⎢⎣
⎡
−−
= 22
21
32
31
32
rrrrR
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Cone clutch
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Comparison: Single plate clutch
Cone clutchPlate clutch
W and p are normal to the friction surface dl =drcosecα and pn are normal to the friction surface
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Cone clutchThe total frictional torque T :
R – mean radius
For uniform pressure (for new clutches)
For uniform wear (for old clutches)
WRT µ=
[ ] αecrrR cos2
21 +=
αecrrrrR cos
32
22
21
32
31 ⎥
⎦
⎤⎢⎣
⎡
−−
=
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Cone clutchEngagement
Axial force required for engaging the clutch
For free disengagement
αµ cosne WWW +=
)cos(sin αµα += ne WW
)cos(sin αµα −= ne WW
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Centrifugal clutch
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Centrifugal clutch
RnPPT sc )( −= µ2ωmrPc =2
1ωmrPs =
m – mass of each shoen – number of shoesr - Distance to the centre of gravity of the shoe from the centre of the spiderR – inside radius of pulley rimω – angular speed of the pulley in rad/sω1 – angular speed at the beginning of the engagementµ- coefficient of friction
The total frictional torque
