Mechanical Measurements Design Project

Gear Trains

By: Justin Del Borrello Sean Brook Brandon Chabala

Motivation

Objectives• To study the speed ratios and directions of simple and

compound gear trains.

• To determine the output torque of simple and compound gear trains.

• To determine if mechanical power is conserved through a gear train system.

Different Gear Ratios

• Small to Large– Decrease Speed but Increase Torque– Gear Ratio >1 (Down Gearing)

• Large to Small– Increase Speed but Decrease Torque– Gear Ratio < 1 (Up Gearing)

Types of Gear Trains• 1. Simple gear train

• 2. Compound gear train

• 3. Reverted gear train

• 4. Epicyclic gear train

Simple Gear Train

• Bicycle Gearing

Simple Gear Train: There is only one gear per shaft

Compound Gear Train

• Simple Transmission

Compound Gear Train: There can be more than one gear per shaft

The Experiment Setup

Materials Used

Experimental Setup

• AC to DC Power Supply

• Scientific Weights• Stroboscope

• DC Motor• Bearings• Shafts• Gears

Ways to Measure Angular Velocity• Tachometer

– Measure rotations of shaft at the tip of meter

• Stroboscope– Uses strobe light to make

objects appear stationary

Ways to Measure Torque

• Dynamometer– Device for measuring

force, torque, power or RPMs

• Prony Brake– Simple Dynamometer

using braking force and an extended load

Analysis

Velocity Analysis

– N= number of Teeth– ω=angular velocity

•  

Torque Analysis

𝑅=𝑁𝑐

𝑁𝐴

=0.5

Experimental Results

Voltage (V)

Power in (Watt)

Power out (Watt)

RPM in RPM out T2 (Nm)

T4 (Nm) Ratio

8 10.2 9.34 404 339 0.24 0.26 1.1112 18.09 16.53 480 412 0.36 0.38 1.1116 24.12 22.41 533 470 0.43 0.45 1.11

Compound Gear Train

Simple Gear Train

Voltage (V)

Power in (Watt)

Power out (Watt)

RPM in RPM out T2 (Nm)

T5 (Nm) T Ratio

8 10.5 9.83 285 135 0.35 0.69 2.1312 16.29 14.31 330 146 0.47 0.93 2.1316 24.12 22.91 440 212 0.52 1.03 2.13

Comparison of Results

T5 (Theo.)

T5 (Exp.)

% Diff.

0.75 0.69 7.29

1.00 0.93 6.91

1.11 1.03 7.56

Angular Velocity (Theo.)

Angular Velocity (Exp.)

% Diff.

13.92 14.13 1.50

16.12 15.28 5.19

21.57 22.20 2.91

Power (Theo.)

Power(Exp.)

% Diff.

10.50 9.83 6.31

16.29 14.31 12.13

24.12 22.91 4.98

Power (Theo.)

Power(Exp.)

% Diff.

10.2 9.34 8.40

18.09 16.53 8.57

24.12 22.41 7.06

Angular Velocity (Theo.)

Angular Velocity (Exp.)

% Diff.

38.07 35.50 6.76

45.23 43.14 4.63

50.23 49.21 2.02

T4 (Theo.)

T4 (Exp.)

% Diff.

0.26 0.26 1.75

0.40 0.38 4.13

0.48 0.45 5.14

Simple Gear Train

Sources of Error• Mass of the Gears was not taken into account• Stroboscope not perfectly accurate• Not perfectly meshed together• Not having Exact Mass Value • Friction between bearings• Motor Efficiency ~75%• Loose Gears

Conclusions• Gear ratio, velocity and torque of different gear trains within desired

range of accuracy were determined • Compound gear trains have a higher gear ratio than simple trains• Direction of angular velocity changes with the addition of the

number of gears for simple and compound gear trains• Mechanical power is conserved throughout the system• Compound conserves space with also gaining more torque or speed

output as well as greater gear ratio possibilities• Increased voltage delivers higher speed & torque

Questions?