Types of Gears - Bearings

1 .GEARS 

2 . Gears • Rugged • Durable • Can transmit power with up to 98% efficiency • Long service life 

3 . Motors • Motors convert electrical energy to mechanical energy. • Mechanical energy moves our robot • Motors drive the gears http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LR9520&P=DS 

4 .– Spur Gears • Flat • Pinion – Bevel • Crown – Worm – Rack and Pinion – Differential www.mathworks.com 

5 . Gears • Toothed wheels fixed to an axle. • Drive gear – connected to the input axle. • Driven gear – connected to the output axle. • Gear train – when an number of gears are connected together. Number of driven teeth (output) Gear Ratio = Number of driver teeth (input) 

6 . Gear and Bearing Assemblies • Use as few views as possible – A full sectional view may be the only view necessary • Dimensions are normally omitted • Typically include balloons correlated with a parts list • May include torque data and lubricant information 

7 .Gear and Bearing Assemblies 

8 . Applications of Gears • Toys and Small Mechanisms – small, low load, low cost kinematic analysis • Appliance gears – long life, low noise & cost, low to moderate load kinematic & some stress analysis • Power transmission – long life, high load and speed kinematic & stress analysis • Aerospace gears – light weight, moderate to high load kinematic & stress analysis • Control gears – long life, low noise, precision gears kinematic & stress analysis 

9 . Spur Gears – Straight teeth mounted on parallel shafts – Many used at once to create very large gear reductions • Flat • Pinion http://en.wikipedia.org/wiki/Gear#Worm_gear 

10 . Types of Gears Gear (large gear) Spur gears – tooth profile is parallel to the axis of rotation, transmits motion between parallel shafts. Internal gears Pinion (small gear) Helical gears – teeth are inclined to the axis of rotation, the angle provides more gradual engagement of the teeth during meshing, transmits motion between parallel shafts. 10 Mechanical Engineering Dept. Ken Youssefi 

11 . Spur Gear Terminology • Teeth are straight and parallel to the gear shaft axis • Establish gear tooth profile using an involute curve • Basic rule: – No fewer than 13 teeth on the running gear and 26 teeth on the mating gear 

12 . Spur Gear Terminology • Pressure angle – 14.5°and 20°are standard • Diametral pitch • Gear accuracy – Maximum tooth-to-tooth tolerances allowed, as specified by the American Gear Manufacturers Association (AGMA) • Several additional formulas and specifications 

13 . Bevel Gears – Gears that mesh at an angle, usually 90° – Changes the direction of rotation http://science.howstuffworks.com/gear4.htm 

14 . Bevel Gears • Shafts of the gear and pinion can intersect at 90°or any desired angle • Provide for a speed change between the gear and pinion, unless designed as miter gears 

15 . Types of Gears Bevel gears – teeth are formed on a Straight conical surface, used to transfer bevel gear motion between non-parallel and intersecting shafts. Spiral bevel gear 15 Mechanical Engineering Dept. Ken Youssefi 

16 . Crown Gears – Special form of bevel gear – Has right angles to the plane of the wheel http://www.plastic-gear-manufacturer.com/industrial-gear.htm 

17 . Worm Gears – Changes the direction of turning motion by 90° – Decreases the speed of turning from screw to gear and increases the force http://blogs.toolbarn.com/brianm/labels/Tool%20Inner%20Workings.html 

18 .Worm Gear Print 

19 . Worm Gears • Use a worm and worm gear • Large speed reduction in a small space • Worm locks in place when not in operation 

20 . Rack and Pinion – Converts rotary motion to back and forth motion http://en.wikipedia.org/wiki/Gear#Worm_gear 

21 . Rack and Pinion • Spur pinion operating on a flat straight bar rack • Converts rotary motion into straight-line motion 

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23 . Differential Gears – Splits torque two ways, allowing each output to spin at a different speed http://nxtasy.org/wp-content/uploads/2006/08/Differential2-00.html 

24 . Spur Gears • Transmit motion and power between parallel shafts • Two basic types: – External spur gears – Internal spur gears • Cluster gears 

25 . Spur Gears • Advantages: – Economical – Simple design – Ease of maintenance • Disadvantages: – Less load capacity – Higher noise levels 

26 . Helical Gears • Teeth cut at an angle – Allows more than one tooth to be in contact 

27 . Crossed Helical Gears • Also known as: – Right angle helical gears – Spiral gears • Low load-carrying capabilities 

28 . Helical Gears • Carry more load than equivalent-sized spur gears • Operate more quietly and smoothly • Develop end thrust – Can be eliminated using double helical gears, such as a herringbone gear 

29 . Gear Assemblies