Environmental Engineering Reference
In-Depth Information
Coupling
Gear
box
Main
bearing
Main
shaft
Generator
Hub
FIGURE 2.2
The.line.between.the.wind.turbine.blade.and.generator.
Transmissions. include. main. bearing,. main. shaft,. gearbox,. coupling,. and.
generator..Most.modern.gearboxes.are.used.to.increase.torque.while.reduc-
ing.the.speed.of.a.prime.mover.output.shaft.(e.g.,.a.motor.crankshaft)..This.
means.that.the.output.shaft.of.a.gearbox.will.rotate.at.a.slower.rate.than.the.
input.shaft,.and.this.reduction.in.speed.will.produce.a.mechanical.advan-
tage.causing.an.increase.in.torque..A.gearbox.can.be.set.up.to.do.the.opposite.
and.provide.an.increase.in.shaft.speed.with.a.reduction.of.torque..Some.of.
the.simplest.gearboxes.merely.change.the.physical.direction.in.which.power.
is.transmitted.
Many.typical.automobile.transmissions.include.the.ability.to.select.one.of.
several.different.gear.ratios..In.this.case,.most.of.the.gear.ratios.(often.sim-
ply.called. gears ).are.used.to.slow.down.the.output.speed.of.the.engine.and.
increase.torque..However,.the.highest.gears.may.be.“overdrive”.types.that.
increase.the.output.speed.
Gearboxes. have. found. use. in. a. wide. variety. of. different—often. station-
ary—applications,.such.as.wind.turbines.
Transmissions. also. are. used. in. agricultural,. industrial,. construction,.
mining,. and. automotive. equipment.. In. addition. to. ordinary. transmission.
equipped.with.gears,.such.equipment.makes.extensive.use.of.the.hydrostatic.
drive.and.electrical.adjustable-speed.drives.
The.simplest.transmissions,.often.called.gearboxes.to.relect.their.simplic-
ity.(although.complex.systems.are.also.called.gearboxes.in.the.vernacular),.
provide.gear.reduction.(or,.more.rarely,.an.increase.in.speed),.sometimes.in.
conjunction.with.a.right-angle.change.in.direction.of.the.shaft.(typically.in.
helicopters)..These.are.often.used.on.powered.agricultural.equipment,.since.
the.axial.shaft.is.at.odds.with.the.usual.need.for.the.driven.shaft,.which.is.
either. vertical. (as. with. rotary. mowers). or. horizontally. extending. from. one.
side. of. the. implement. to. another. (as. with. manure. spreaders,. lail. mowers,.
and.forage.wagons)..More.complex.equipment,.such.as.silage.choppers.and.
snow.blowers,.have.drives.with.outputs.in.more.than.one.direction.
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