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Gearbox Design Project

Kirk Stanwix Tajinder SinghGai Ayuel Gai

MEE30003 – MACHINE DESIGN2017 SEMESTER 1

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Types of gears

• Spur Gears• Helical Gears• Worm Gears• Planetary Gears

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Spur Gears

• Pros Reduce speed and increase torque Change rotational direction Simple in operation Reliable at low speeds

• ConsCant handle large amounts of torqueNoisy at high speedsRequires many gears for large reductions

Figure 1 – Spur Gear

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Helical Gears

• ProsCheap to manufactureSimple in operationGood Torque and noise properties

• ConsMore Complex and generally more expensive compare to

spur gearsLess noise than spur gears at high speedsRequire many gears for large reductions

Figure 2 – Helical Gear

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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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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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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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Table of Gear RatiosGear Input Output Stationary CalculationA 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•

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Force Analysis

Figure 5 – FBD of weight and ramp

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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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Power

• Power produced by the planetary gears can then be determined by the following equations:1. (W)2. (N)

3. (W)

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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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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