power train components mjh

8/7/2019 Power Train Components mjh

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Power Train ComponentsPower Train Components


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IntroductionIntroduction Reduction Gears - fast to slow

Lubrication System - overcome friction Shaft components - turbines to the working

medium (ocean)

Propeller - transform rotational energy intothrust


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Reduction GearsReduction Gears Purposes

Allow turbine andpropeller to operateat most efficientspeeds

Combine twoturbines to commonshaft


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Reduction GearsReduction Gears Reduction Process

Pinion (small) geardrives reduction (large)gear

Reduction ratio = turnsof pinion : turns ofreduction gear

DoubleDouble--reductionreduction:reduction in 2 steps(more compact design)

For naval reduction

gears, normally 30:1


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Reduction GearsReduction Gears Locked TrainLocked Train

Two sets of gears andshafts

Torque transmittedequally

Increases ability totransmit torque usingsmaller components

Turbine shaftsconnected to reductiongears by flexiblecouplings to allow for

thermal expansion


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Shaft Turning/Jacking GearShaft Turning/Jacking Gear Electric motor that

rotates reduction gears,turbines, and shaft w/ousing steam

Cool down turbines afteroperation

Prior to startup for evenheating

Position for maintenance Can be used to lock shaft

in place In event of casualty (i.e.,

loss of lube oil)


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Shaft BearingsShaft Bearings Designed to support the

moving parts of: Shaft

Turbines

Thrust bearings Absorb axial forces

Ex: Kingsbury Thrustbearing

Radial (Journal) bearings Absorb radial forces


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Lube Oil SystemLube Oil System Provide lubrication and remove heat generated by

bearings in overcoming friction

Major components: Sump

Pump

Strainer

Cooler

Bearings

Sump

PumpStrainer

Moving Parts

CoolerSW


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Lube Oil SystemLube Oil System Lube oil can be kept in service for a long

time if kept pure (two methods)

Batch Purification In-port only

Uses heated settling tank

Continuous Purification At-sea method

Centrifugal purifier separates oil &contaminants


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Propulsion ShaftPropulsion Shaft Shaft is hollow: reduces weight & increases

resiliency

Consists of four sections

Thrust shaftThrust shaft - from thrust bearing in reductiongears to end of engineroom

Line shaftLine shaft - located in shaft alley (supported byline shaft bearings)

Stern shaftStern shaft - part of shaft which penetrates hull(supported by Stern Tube bearings)

Propeller shaftPropeller shaft - shaft connected to propeller(supported by Strut Bearings)


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Propulsion ShaftPropulsion Shaft Different sections needed for easy

installation, removal, & maintenance


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PropellerPropeller Made of hub and blades & creates the thrust

necessary to propel the ship through the water

Terms:Pitch:Pitch: axialdistance advancedduring onecompleterevolution of screw

Face:Face: the pressureside

Back:Back: the suctionside


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Propeller TypesPropeller Types Constant vs. Variable Pitch

Variable has the twisted look

Adv: more efficient over widerange of speeds

Fixed vs. Controllable Pitch In controllable, blades can

rotate on hub to change pitch

(change direction) Right vs. Left Hand Screw

Viewed from aft of ship

Twin-screw ships have one of

each


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PropellerPropeller Cavitation

Formation and subsequent collapse of bubbles as

propeller turns Occurs at critical speed

Effects High level of underwater noise

Erosion of blades Vibrabtion with subsequent blade failure from

metallic fatigue

Overall loss of propeller efficiency


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Propeller Power vs. Shaft RPMPropeller Power vs. Shaft RPM Flow E RPM; Thrust (head) ERPM2;

Power E RPM3

So, if 10% power yields 100 RPM, howmuch power will produce 200 RPM?

10% x%1003 2003 x = 10 * (200/100)3

= 80% power80% power


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Questions?Questions?

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