Kirk Stanwix Tajinder Singh Gai Ayuel Gai

1. Gearbox Design Project
Kirk Stanwix
Tajinder Singh
Gai Ayuel Gai
MEE30003 – MACHINE DESIGN
2017 SEMESTER 1
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2. Types of gears
• Spur Gears
• Helical Gears
• Worm Gears
• Planetary Gears
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3. Spur Gears
• Pros
 Reduce speed and increase torque
 Change rotational direction
 Simple in operation
 Reliable at low speeds
• Cons
Cant handle large amounts of torque
Noisy at high speeds
Requires many gears for large reductions
Figure 1 – Spur Gear
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4. Helical Gears
• Pros
Cheap to manufacture
Simple in operation
Good Torque and noise properties
• Cons
More Complex and generally more expensive
compare to spur gears
Less noise than spur gears at high speeds
Require many gears for large reductions
Figure 2 – Helical Gear
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5. Worm Gears
• Pros
 Can handle extremely large reductions
 Simple in operation and easy to maintain
 Large torque capabilities
 Good toque and noise properties
 Can be used in breaking systems
• Cons
 Low efficiency
 Not available or suitable for high speed rotation
 Output shaft is generally fixed at a fight angle to the motor output
shaft
 The worm can creep, if the load is large enough
Figure 3 – Worm Gear
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6. Planetary Gears
• Pros
 Can handle extremely large reductions
 Good load distribution
 Very large torque capability
 High efficiency (loss of 3% per train)
 Can be small in size
• Cons
 High strees on the output shaft bearings
 Can be noisy at high speeds
 Generally expensive to manufacture
Figure 4 – Planetary Gear
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7. Planetary Gears
Reasons for selection:
• Capable of producing large torques
• Can be relatively small in size
• Can increase torque by a factor of 10:1
• More planetary gears results in greater load
capacity while also reducing stress on the
shaft bearings
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8. Table of Gear Ratios
Gear Input Output Stationary Calculation
A Planet Carrier (C) Ring (R) Sun (S) 1/(1+S/R)
B Sun (S) Planet Carrier (C) Ring (R) 1+(R/S)
C Sun (S) Ring (R) Planet Carrier (C) -R/S
Table 1 – Table for gear ratio formulae in relation to 3 main components of
a planetary gear
• The first gear is an overdrive
• The second is a reduction
• The last is also a reduction in reverse
• 𝑁 𝑠 𝜔 𝑠 + 𝑁𝑟𝜔 𝑟 = 𝑁 𝑠 + 𝑁𝑟 𝜔 𝑐
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9. Force Analysis
Figure 5 – FBD of weight and ramp
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10. Force Analysis
Material Kinetic (μ) Static (μ) Force(N)
Wood on Wood 0.3 0.42 99.50033076
Steel on Steel 0.57 0.74 121.1215352
Copper on Steel 0.36 0.53 106.9326198
Ice on Ice 0.03 0.1 77.87912637
Metal on Metal
(Lubricated) 0.06 0.15 81.2574396
Table 2 – Force analysis of minimum force required to
overcome static friction on ramp
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11. Power
• Power produced by the planetary gears can
then be determined by the following
equations:
1. 𝑃 = 𝐹𝑣 (W)
2. 𝐹 =
𝑇
𝑟
(N)
3. 𝑣 =
2𝜋𝑟𝜔
60
(m/s)
4. 𝑃 =
𝑇
𝑟
𝜋𝑟𝜔
30
(W)
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12. Working With Acrylic
• Pros
 Strong and lightweight
 Can easily be restored to original shape
 Sturdy and somewhat unbreakable
 Highly transparent
 Lower manufacturing costs compared to metals
• Cons
 Output shaft is generally fixed at a fight angle to the motor output shaft
 Requires a lot of care and maintenance
 Not very strong, compared to other synthetics
 Subject to cracking under stress
 Low continuous service temperature
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13. What’s next
• Explore how altering the number of planetary
gears affects torque density and stress on
shaft bearings
• Determine how all gears will be mounted into
one system
• Play around with ratios to optimize
performance
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