Gear Box Creative journey

1. Triple M Team
Creative journey
A discussion of Spur and Planetary gear sets

2. Understanding the problem: Performance Equation
Where;
m= Mass to be Lifted (10kg)
g= Acceleration due to gravity
h= Height the weight is lifted (0.5m)
t= Time to lift weight by distance h
V=Motor Voltage
I=Motor Current
D= Maximum Axial length of the gearbox

3. Mindmap

4. High torque Small form
factor
Compatible
with orthogonal
cut
Spur x x
Helical x
Bevel x
Worm x x
Rack and
pinion
x x
Planetary x x x
Possible solutions

5. Planetary gears vs Compound gear discussion
Planetary Compound (Spur)
● High Torque
● A Compact alternative to standard
Compound gearboxes. Which can
produce the same reduction ratio at
a significantly reduced size.
● The Load is evenly distributed
amongst the planetary gears.
Therefore, additional planetary
gears may be added in the case of
high loads.
● High Efficiency
● Complex Design
● High Torque
● Significantly larger in size for an
equal reduction ratio, therefore
more material usage.
● High load at the point of contact,
therefore is prone to tooth wear.
● Loud at high RPM, due to low
Contact Ratio.
● Simple Design, easier maintenance.

6. Required Gear Ratio:
● Assuming a Coefficient of friction of 0.25 was used, a gear ratio of 34:1 is
required in order the lift 10kg a minimum of 0.5m.

7. Our solution the planetary gear set
Why we went with the planetary;
The calculated Data clearly
states that at an equal ratio,
the planetary gear required a
significantly reduced Pitch
Diameter. Therefore, resulting
in a more compact design.

8. Initial Designs
In a planetary gear motor, the input
shaft drives the central (sun) gear,
which then turns the surrounding
(planet) gears. This arrangement allows
each of the planet gears to deliver
torque in perfect synchronization with
the others, which leads to greater
output capacity and takes the pressure
off of each individual gear.
Planetary gearSpur gear

9. What’s wrong with our solution:
Complexity:
The relative complexity of the planetary gear set is a problem with our
solution.
A spur gear set does not need the tolerances to be so tight.
Torque is limited in spur motor gears since each gear bears the whole load.
There are more components in a planetary gear set, therefore a higher risk of
problems in manufacturing errors and human error

10. What is right for our solution:
The planetary gear set has a high power to size ratio.
It therefore should reduce the amount of material needed for manufacture
A planetary gear motor shares the torsional load over several planet gears, so
it works well when a higher torque is required. So there is less worry about
wear and stress, which makes it easier to attain large amounts of power
transfer without harming the gears.

11. Possible applications