Express-O Commuter Trike

DESIGN PROJECT PRESENTATION

Department of Mechanical Engineering

Dalhousie University

Halifax, Nova Scotia

Team 4 – Express-O

Supervisor

Dr. A. Warkentin

Dept. of Mechanical Eng.

Dalhousie University

• Patricia Gillis

• Ahad Ahmed

• Matthew Rockwell

• Matthias Eisengruber

• Jayme Whalen

Clients

PROBLEM Increase in Commuter traffic in HRM

Congested Highways

Environmental Pollution

Parking space shortages

SOLUTION

Environmentally Friendly

Reduce traffic congestion

Average business person

Problem Definition

Express-O Design

Steering

Banking

Drive Train Frame

Braking

Frame and Seat

1 3/8” Chromoly Steel Tubing

Re-use rear triangle

Adjustable seat 60o from Horizontal

Rear Triangle

from Bicycle

Drivetrain 80 rpm Comfortable,

Efficient pedal cadence

Gearing 3 X 7 Rear drive train Fixed ratio Front drive

train

DrivetrainHigh Gear 1 : 3.5 Gear Ratio Max Speed @ 80rpm

input: 35 km/h

Low Gear 1 : 0.69 Gear Ratio Max Speed @ 80rpm

input = 6.8 km/h

Front Middle Rear

Chain Routing

Braking Dual Front Disc Brakes

Radical© Brand Mechanical Disc Brakes

Tilting: Theory Shifts Center of Gravity Normal Force on inside wheel is

increased Tipping occurs when Normal force = 0

H

D

F

mg

FFA

yx x

FN

H

yy

Tilting: TheoryTurning Velocity Stability in Turns

Effect of TiltingOn Maximum Turning Velocity

0.000

1.000

2.000

3.000

4.000

5.000

6.000

0 5 10 15 20 25 30

Tilt Angle Beta (deg)

Max

Tu

rnin

g V

elo

cit

y (

m/s

)

0.400

0.450

0.500

0.550

0.600

0.650

Max

Tu

rnin

g v

elo

cit

y (

g)

Tilt Angle vs. Velocity

Tilt Angle vs. G-Force

Tilting: Links Thickness of Link – 1” thick x

1.5” high Holes for bushing and spring

housing

Diamond Plate

Horizontal Tilt Link

Bushing

Steering: Theory

Ackerman Steering

Centre Point Steering

Caster Effect Wheel Camber

Steering: Rider Input Vertical Steering Arms

Connected to L-bracket on bottom of the stub axle

Located at both sides of the rider

Can move forward and backward

Manufacturing• Parts needed for Assembly : Qty 88 Parts

• Tasks:

• Acquisition of Material

• Off the Shelf – 44 parts

• Student built – 32 parts

• Technician Built – 12 parts

• Dimensioning

• Machining

• Welding

• Assembly

Major Design Changes

Tilting System Materials Brakes Drive train

Changes to Tilting System Replaced bearings with bushings

Closer fit More contact surface

Added springs Static stability Return from banking position

Changes to Materials Most parts originally designed to be

fabricated from steel To reduce weight, cost some parts were

fabricated from aluminum These include:

Horizontal tilt links Steering L-brackets Steering arms

Changes to Brakes

Omitted rear V-brake Vehicle now has dual

front disc brakes only Disc brakes provide

sufficient braking power

Simplified the braking system

Changes to Drive Train

Originally designed to have three derailleurs

Now has two derailleurs

Lower gear ratio

Finite Element Analysis

Horizontal Tilt Links Stub Axles

Design Requirements:

Survive: 5Km/H impact with curb 0.16 m drop off curb Safety Factor: 3

Analysis

FEM RESULTS Max Force:

1800 N

Max Stress: 90 MPa

Al 6061 T6 Yield Strength: 276 MPa

Stub Axles Max Force:

1800 N

Max Stress: 200 MPA

1020 Steel Yield Strength: 346 MPa

Future Improvements

Horizontal Tilt Link Mounts Chain Pulley Brackets Spherical Ball Ends Spring and Damper Set Up Seat

Horizontal Tilt Link Mounts

Problem: Cantilevered Bolt acts a

Pivot Bolt bends when forces

act on Links Fix:

Second Diamond Plate

Chain Pulley Brackets Problem:

Cantilevered Bolt Bolt bends when Chain is

under tension Regular Idler Gear not

designed to run on an angle Fix:

Second Adjustable Plate

Spherical Ball Ends

Problem: Inexpensive Rod Ends

with unknown load rating Not quite enough

freedom to move Premature Failure

Fix: Higher Budget to buy

specked out Rod Ends

Spring and Damper Set Up Problem:

Springs need to be adjusted according to rider weight for smooth banking

Banking motion is not continuous

Fix: Adjustable Spring Mounts Light Damper to “smooth

out” banking motion

Seat Problem:

Not enough side support

Makes leaning into corners harder

Fix: Deeper Sling Seat

Design

Accessories

Lexan/Plexiglas Enclosure Lights Flag More Storage Compartments Toolkit Cup holder

Original Scope

Safety Durability Complexity Physical

Specs

Ergonomics Materials Costs

Safety

Safe to operate Visible in traffic Stable Durable Protection of rider

from moving parts

Durability Withstand environmental conditions

This has not been fully tested

Withstand road conditions (i.e. potholes) Seems to ride well on road surfaces Survived speed bumps!

Complexity

Simple & Functional Easy to Manufacture &

Repair Standard “off-the-shelf”

Parts Brakes Wheels Chaining Rear Triangle

Physical Specs Original Dimensions

Width: 1.5m Length: 3m Height: 2m Weight: 50kg

Actual Dimensions Width: 1.12m Length: 2.15m Height: 0.82m Weight: 29kg

Ergonomics Sized comfortably for one adult

Adjustable seat to pedal distance Seat at a comfortable height

Simple to operate Intuitive steering Learning curve to mastering

tilting

Easy to Mount/Dismount Relatively easy – except position

of tilt links

Ergonomics (continued)

Reduced physical power input Relatively easy to pedal

Protection from weather Not included due to time and

money Options for future adaptations

Cargo Space to fit backpack/briefcase Rack over rear wheel Extra space behind seat

Materials Minimize costs and meet

design requirements Recycled Parts Donated Material

Light, durable, easily machined Changed some parts to aluminum Durability issues with the chaining Stub axles were the most

complicated part

Cost Ceiling price of $2000

Total estimated cost $1221.96 ($785.95 with donations) Actual cost $825.15

Keep cost to a minimum Donated Material Recycled Parts Money Donations

Necessary but expensive parts Additional costs for bolts, springs, etc.

Criteria Table

Criteria SatisfiedRoom for

Improvements

Safety Durability Complexity Physical Specs Ergonomics Materials Costs

Testing Performance Goals

Turning Radius Cruising Speed Maximum Speed Stability Stopping Distance Reliability

Cornering / Turning Radius Goal

Capable of maneuvering on city streets

Test Result Acceptable turning

radius of 6m @ 15km/h

Cruising / Max Speed Goal

Comfortable cruising speed of 15km/h

Maximum speed of approximately 50km/h

Test Result 15km/h is easily

attainable Maximum Speed

obtained of 45km/h

Stability Goal

Stable when stationary (i.e. Stoplight) Stable at high speed Stable while cornering

Test Result Stable with the aid of front brakes and

practice Low speed stability is slightly less than

desired High speed stability is as expected

Performs very well at high speeds “Hugs” tight corners at high speeds

Stopping Distance

Goal Maximum stopping

distance of 6m

Test Result At cruising speeds

(~15km/h) : <2m At max speed

(45km/h): 7m

Reliability Goal

1350km/year with minimal maintenance

Test Result Chain tension system on the prototype is not

very reliable Tilting linkage would require frequent

adjustment

Conclusion Performance Size and Weight Cost Safe

FUN

Thank You Angus & Albert Paddy Wong & Zack Gus Reed Sportwheels & Bike Doctor Dr. Warkentin

QUESTIONS?