Machine DesignCreative Journey

Objective

To design and build a gearbox capable of lifting a minimum of 8kg’s between 0.5m to 1m

Being assessed on the criteria of performance. Making sure that the design is as small as possible as well as efficient and quick.

Brainstorm Of Ideas and Items

Gear Box Options

Planetary Gears Elliptical Gears Compound Gears

Planetary Gears

Pros:• Downgrading of

ratio/speed• Distribution of loads• Efficient

Cons:• Difficult to work with• Lot of stresses within

the system• Frictional losses

Elliptical Gears

Pros:• Applying load when

most necessary• Distribution of loads

Cons:• Difficult to work with• Reduction factors are

hard• Positioning of gears

Compound Gears

Pros:• Easy to work with• Good reductions• Easy to repair• Allows for many

possibilities and designs

Cons:• Not as efficient as Planetary• Stresses not distributed• May take up a lot of room to

get right reduction

Chosen Idea

3 tiered planetary system Planetary gears are very good at conversion of torque and speed Due to the system being compact, there are a lot of stresses that need to be taken into

consideration between the gears 3 or more stages are required to get the correct amount of reduction.

3 carrier planets per tier 3 is the optimal amount of planets, it distributes load across all gears whilst not having to

much stress and does not generate as much friction as a four-gear system does.

Sample Calculations and DesignSun to Carrier:1+R/S

Planet to Ring:1/(1+S/R)

Sun to Ring:-R/S

Therefore it can be seen that by keeping the ring gear fixed and having it as big as possible whilst the sun gear smaller the ratio is much larger.

Thank you for watching

Does anybody have any questions?