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SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains
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SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.

Dec 19, 2015

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Page 1: SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.

SUMMER INSTITUTE - ROBOTICS

THE OHIO STATE UNIVERSITY

Drivetrains

Page 2: 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.

Page 3: SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.

Gear Train!?!?!?

Combination of two or more meshed gears. Used to change:

the rate of rotation the direction of rotation the amount of torque.

Page 4: SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.

Gear Ratio (Oh no! Not MATH!)

Gear ratio is also called “Mechanical Advantage”

Gear ratio Number of Driver Teeth

Number of Driven Teeth

Page 5: SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.

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

Page 6: SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.

Types of Gears

• Spur gears

• Worm gear

• Rack and pinion

• Bevel gears

Page 7: SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.

Worm Gears

Used to change speed and direction of rotation.

High gear ratios.Higher load capacity (TORQUE).

What is the gear ratio?

Page 8: SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.

Rack and Pinion

Used to convert rotational motion into linear motion, or vice-versa.

Page 9: SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.

Bevel Gears

Used for intersecting shafts. Most transmissions occur at right angles but

shaft angles can be any value.

Page 10: SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.

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

Page 11: SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.

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)…

Page 12: SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.

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

Page 13: SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.

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

Page 14: SUMMER INSTITUTE - ROBOTICS THE OHIO STATE UNIVERSITY Drivetrains.

OK! Any questions????