Gears & Drives

8/14/2019 Gears & Drives

1/50

Gears & Drives

MEC1010Design and Manufacturing 1

Dr. Simon Smith


2/50

Gears & Drives

Massive subject, for your wind turbines

consider:

How to transmit the turbine power to the

generator

Gearing (speed / torque changes) to match

the speed of the turbine to the speed required

at the generator

Friction losing power between the turbine and

the generator


3/50

Gears & Drives

Transmission of power from source to load


4/50

Gears & Drives

Power source should match load

Engine size to weight of vehicle / performance

required

Turbine size to generator

Consider power losses (friction)

Drive system should be sized appropriately

Clutches, drive shafts, belts

Power / torque / speed


5/50

GEARBOX

GEARBOX

PROP SHAFT

DRIVE SHAFTS

DRIVE SHAFT

DRIVE SHAFT

UNIVERSAL JOINTS


6/50

Transmissions

In British English the term transmission refers

to the whole drive train

Gearbox, clutch, prop shaft, differential, drive

shafts, universal joints, belts, chains, etc

In American English the term transmission

refers only to the gearbox


7/50

Commercial Wind Turbine


8/50

Spur Gears

Simplest of gears

Teeth parallel to

shaft

Rotate on two

parallel shafts


9/50

Direction of Rotation Changes


10/50

Gearing

Ratio of teeth

10:28

speed reducing

28:10

speed increasing

Fixed ratio


11/50

Gears

Can vary in:

Diameter

Width

No. of teeth Material

Tooth form

Gear form


12/50

Where have you seen spur gears?


13/50

Where have you seen spur gears?


14/50

Multiple designs this year

will probably use small spur gears


15/50

Bevel Gears

Allows angle of drive

to be changed

Gearing ratio can bechanged, although

this is 1:1


16/50

Where have you seen bevel gears?


17/50

Where have you seen bevel gears?


18/50

And some designs this year

will probably use bevel gears


19/50

Linear (Rack & Pinion) Gears

Rack can moverelative to shaft

Steering on a car

Shaft can movealong rack

Positional changes

Some swing bridges

Pinion

Rack


20/50

Internal / External Gears

Relative positionchanges

Gearing

Rotation Example might be a

food mixer


21/50

Worm Gears

Screw

Worm wheel

Large gear ratio Often non-reversible & self-locking


22/50

Helical Gears

Teeth set at an angle toaxis of rotation

Advantages

Smoother

Quieter

High speed

Large power transmission

Direction change possible

Disadvantages

Expense

More sliding friction

Axial thrust


23/50

Belt Drives

Simple

Quiet

Smooth

Can tolerate load

changes

No lubrication

required


24/50

Belt Drives

Cheap

Can cope with

misalignment

Can be veryefficient 95%

Can be very

inefficient too!

Can provide

gearing


25/50

Belt must be tensioned correctly


26/50

Belt must be tensioned correctly


27/50

Minimize misalignment


28/50

Widely varying applications


29/50

Can be used as a clutch


30/50

Belt Types


31/50

Timing Belt / Cambelt

Toothed belt

High speed

Reliable

Cheap

Accurate timing


32/50

Some designs this year

will probably use belt drives


33/50

Chain Drive

Strong

Less prone to slipping

Flexible

Usually narrower than a

belt for same power

transmission

Many applications, butoften used in transport

& vehicles


34/50

Chain Drive

Can be cheap

Can provide gearing

Can cope with some

misalignment

As with belt drives -

Tension correctly

Align correctly


35/50

Chain Drive


36/50

Chain drive in biscuit manufacture


37/50

This year we will

probably see chain drives


38/50

Flexible Drives

Power can be

transmitted through

large angles

Minimal assembly

Can be low friction

Can accommodate load

changes


39/50

Flexible Couplings

Allow power transmission

Allow for misalignment

Absorb shock loads

Can protect against

overloads

Can be torque limiting in

some cases


40/50

Flexible Couplings


41/50

Your Design WILL have at least 1

FLEXIBLE COUPLING


42/50

Examples of drive systems

Petrol engine

Shaft drive

Bevel gear

Cutting head


43/50

Many Ways to Transmit Power

Straight shaft drive Bent shaft drive


44/50

Wind Turbines

Straight shaft connection

Gearing is 1:1Should be low friction

Wind shadow?


45/50

Wind Turbines

Parallel shaft connection

Gearing could now be altered

Probably more friction


46/50

Wind Turbines

Perpendicular shafts

Gearing could be altered

Friction likely to increase

Alignment an issue


47/50

Commercial Wind Turbine


48/50

Commercial Wind Turbines


49/50

What WILL Your Design Have?

Blades

Drive system

Bearings

Flexible coupling

Generator


50/50

What Might Your Design Have?

Rigid coupling(s)

More bearings

Another flexible coupling

Gearing

Belt, Chain, Spur, Bevel, etc.

Gears & Drives

Documents

Transcript of Gears & Drives