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SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.
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Transcript of SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.
SUMMER INSTITUTE - ROBOTICS
THE OHIO STATE UNIVERSITY
Drivetrains
GEARS!!!!
A gear is a wheel with teeth along its rim. It is used to transmit effort from one shaft
to another.
Gear Train!?!?!?
Combination of two or more meshed gears. Used to change:
the rate of rotation the direction of rotation the amount of torque.
Gear Ratio (Oh no! Not MATH!)
Gear ratio is also called “Mechanical Advantage”
Gear ratio Number of Driver Teeth
Number of Driven Teeth
Who lifts buckets these days? Let’s talk about CARS!!!
Your good ‘ol run of the mill transmission. sort of.
1st: 3.08:12nd: 1.93:13rd: 1.34:1 4th: 1.0:1
Types of Gears
• Spur gears
• Worm gear
• Rack and pinion
• Bevel gears
Worm Gears
Used to change speed and direction of rotation.
High gear ratios.Higher load capacity (TORQUE).
What is the gear ratio?
Rack and Pinion
Used to convert rotational motion into linear motion, or vice-versa.
Bevel Gears
Used for intersecting shafts. Most transmissions occur at right angles but
shaft angles can be any value.
Chains and Pulleys – sort of like gears…
Like gears, but pinions don’t meshTransfers motion longer distancesGear ratio equation works the sameSome pulleys don’t
have teeth, can slip
Caterpillar skid steerdrive system
The Task:
Develop a drive train to pull as much weight as possible up a ramp as quickly as possible.
You will have to make a tradeoff between TORQUE and SPEED (there’s that gear ratio again).
Here’s some math to help you out (what engineers do before they build things)…
P. 12
WWN
WII
P
FI
Sum of Forces parallel to plane = 0 P - WII - FI = 0
7
3
Check the length and height of the ramp
Static (Const. Velocity) Analysis
P. 13
P - WII - FI = 0 WII = W sin (slope angle) slope angle = atan(3/7) = ~23 degrees WII = 5 lbs (sin(23)) = 1.97 lb P = 1.97 lb + 0.5 lb = 2.47 lb Torque = P x Radius of Wheel = 2.47 x 0.875 = 2.16 lb-in = 34.6 oz - in
Torque
Speed
Stall
No Load Speed
Usable performance
Static (Const. Velocity) Analysis
OK! Any questions????