Project Final

A REPORT

ON

Design of Brake calliper assembly unit for Bicycles

BY

Name of Student ID No.

Sodisetty V N B Prasad 2010H141033G

P.N.Uday 2010H141029G

M.E (Design)

Prepared in partial fulfilment of the course

Product Design

BIRLA INSTITUTE OF TECHNOLOGY AND SCIENCE, PILANI

November 2011

Table of contents

1. Introduction

2. Mission statement

3. Technical questionnaire

4. Customers need by questionnaire

5. Grouping of customers’ needs

6. List of metrics

7. Black box model

8. Activity diagram

9. Design drivers

10. FAST method

11. SOP Procedure

12. Function tree

13. Technology road map

14. Cost scenario

15. Product life cycle

16. Concept generation

17. Concept screening

18. Conclusion

19. References

Introduction

A bicycle brake is used to slow down or stop a bicycle. The three main types of brakes are: rim brakes, disc

brakes, and drum brakes. Most bicycle brake systems consist of three main components: a mechanism for the

rider to apply the brakes, such as brake levers or pedals; a mechanism for transmitting that signal, such as

Bowden cables, hydraulic hoses, rods, or the bicycle chain; and the brake mechanism itself, a calliper or drum,

to press two or more surfaces together in order to convert, via friction, kinetic energy of the bike and rider into

thermal energy to be dissipated.

Spoon Brake

The spoon brake consists of a pad (often leather) or metal shoe (rubber faced), which is pressed onto the top of

the front tyre. These were always rod-operated by a right-hand lever. It consists of a spring-loaded flap attached

to the back of the fork crown. This is depressed against the front tyre by the rider's foot.

Advantages and disadvantages of spoon brake

Perhaps more so than any other form of bicycle brake, the spoon brake is sensitive to road conditions and

increases tyre wear dramatically.

Duck Brake

The duck brake or Duck Roller Brake used a rod operated by a lever on the handlebar to pull twin friction rollers

(wood or rubber) against the front tyre.Mounted on axles secured by friction washers and set at an angle to

conform to the shape of the tyre, the rollers were forced against their friction washers upon contacting the tyre,

thus braking the front wheel.A tension spring held the rollers away from the tyre except when braking.Braking

power was enhanced by an extra-long brake lever mounted in parallel with and behind the handlebar, which

provided additional leverage when braking (two hands could be used to pull the lever if necessary.

Rim brakes

In this type of brakes, Braking force is applied by friction pads to the rim of the rotating wheel, thus slowing it

and the bicycle. Brake pads can be made of leather, rubber or cork and are mounted in metal "shoes". Rim

brakes are typically actuated by the rider squeezing a lever mounted on the handlebar.

Types of Rim brakes

1) Rod-actuated brakes

The rod brakes also called as stirrup brakes uses a series of rods and pivots, rather than Bowden cables, to

transmit force applied to a hand lever to pull friction pads upwards against the inner surface, which faces the

hub, of the wheel rim. Rod brakes are used with a rim profile known as the Westwood rim, which has a slightly

concave area on the braking surface and lacks the flat outer surface required by brakes that apply the pads on

opposite sides of the rim. The rear linkage mechanism is complicated by the need to allow rotation where the

fork and handlebars attach to the frame.

2) The calliper brakes

The calliper brake is a class of cable-actuated brake in which the brake mounts to a single point above the

wheel, theoretically allowing the arms to auto-centre on the rim. Arms extend around the tyre and end in brake

shoes that press against the rim. While some designs incorporate dual pivot points, the arms pivot on a sub-

frame and the entire assembly still mounts to a single point.

3) Disc Brake

A disc brake consists of a metal disc attached to the wheel hub that rotates with the wheel. Callipers are attached

to the frame or fork along with pads that squeeze together on the disc. As the pads drag against the disc, the

wheel - and thus the bicycle - is slowed as kinetic energy (motion) is transformed into thermal energy (heat). (In

basic operation, disc brakes are identical to rim brakes.) A bicycle disc brake may be mechanically actuated, as

with a Bowden cable, or hydraulically actuated, or a combination of the two.

Types Of Disk Brakes

There are two main types of disc brake: mechanical (cable-actuated) and hydraulic..

Advantage of Hydraulic Brake

Modern hydraulic disc brakes generate more stopping power than mechanically actuated disc brakes.

Advantages Of Mechanical Brakes

The advantages of mechanically actuated disc brakes are in their lower cost, lower maintenance, and lighter

system weight. Additionally, mechanically actuated disc brakes can be used with drop handlebars.

Advantages of disc Brakes

Disc brakes tend to perform equally well in all conditions including water, mud, and snow due to several

factors:

1. The braking surface is farther from the ground and possible contaminants like mud which can coat or freeze

on the rim and pads.

2. Disc brake pads when fully retracted ride much closer to the braking surface than rim brake pads.This better

prevents a build-up of water or debris under the pad.

3. There are holes in the rotor, providing a path for water and debris to get out from under the pads.

Drum brakes

Bicycle drum brakes operate like those of a car, although the bicycle variety use mechanical rather than

hydraulic actuation. Two pads are pressed outward against the braking surface on the inside of the hub shell.

Shell inside diameters on a bicycle drum brake are typically 70 – 120 mm. Drum brakes have been used on front

hubs and hubs with both internal and external freewheels. Both cable- and rod-operated drum brake systems

have been widely produced.

Mission statement: Bicycle brake calliper product

Product Description:Stops a bicycle in the quickest time and also is economically feasible.

Key business or humanitarian goals: 2 months design and development of prototype.

Primary market: General usage for students and common people

Secondary market: Ardent Bikers

Assumptions:Operating cost will be minimal. Quick in action. Long Life, less wear of pads, Less Mechanical

force required.

Avenues for creative design:Ergonomic structure. Different materials for brake pads.

Scope limitations: Reuse of worn out parts. Interchange ability of brake wires.

Technical questioning for the bicycle brake calliper

1) What is the problem really about?

Existing brake callipers wear down quickly and sometimes do not act properly. Replacing worn down parts are

at times higher.

2) What implicit expectation and desires we want?

It should be noiseless, easy to setup and should have quick action.

3) Are stated customer needs, functional requirements and constraints truly appropriate?

The original concept is developed considering the problems faced by the students and customers based on their

interviews. The replacement sometimes becomes a costly affair,

4) What avenues are open for creative design?

Different materials can be used for brake pads and processes can be used to reuse the rubber from the worn out

pads.

5) What avenues are limited or not open for creative design? Limitations and scope:

No reuse of worn out parts. No electrical power

6) What characteristic/ properties must the product have?

It should be easy to install, durable, and have adjustable straddle wire.

7) What aspects of the design task can and should be quantified now?

Customer Needs analysis, development costs to be covered by profits, research estimates should be carried out

to understand competition.

8) What are the technical and technological conflicts inherent in the design task?

Compact size vs. balancing surface area and larger mechanical advantage.

Like/dislike method of data collection form

Customer Data: Brake callipers Customer: Siva sai Kodali Interviewer(s): S V N B Prasad & P.N. Uday Address: V.I.T Date: 27-10-2011 Willing to do follow up? Y Currently uses : Rim brakes Type of user: College student Question Costumer need Interpreted need Importance

Typical uses Stopping a bicycle

Likes Pad wear should be minimal Setup should be made easy Parts should be interchangeable alignment shoes Stops quickly when wet Long life and strength Aesthetically pleasing

Less Pad wear Easy to set up Interchange ability is required Easy to toe shoes Great stopping power Durable and rigid Aesthetic pleasing

Good Should Good Good Should Should Good

Dislikes Noise produced during braking Poor performance when rim is wet Prone to clogging with mud Heavier structure Brake lever is tight Slippage of brakes when centre pivot is not correctly placed

Squealing of brakes to be avoided Strong braking conditions Clearance between ground and callipers Light weight Effective force transmission Adjustment and proper alignment

Should Good Good Good Should Good

Suggested improvements

Disc brake Hydraulic braking system Less wear off Make effective braking area more

Customer needs collected by conducting questionnaires and interviews

Grouping of Customer needs

Customer Need Interviewer : P N Uday & S V N B Prasad Sample size : 12 customers Average customer : Male/Female, age 20-30 Weight Students

1. Usage/Manipulation a) Ease of Setup 4

b) Adjustment & proper alignment 3 c) Interchangeability 2

2. Aesthetics a) Aesthetically pleasing 3

3. Stability a) Long life & strength 4 b) Resistance to corrosion 3

4. Size a) Light Weight 3 b) Compact 4

5. Proper Working a) Less Pad wear 4 b) Strong Braking 3 c) Effective force transmission 3 d) Good response 3 e) Easy replacements of worn out parts 2

6. Cleaning

a) Mud should not clog on calipers 2

7. Cost a) Installation Cost 3 b) Maintenance Cost 4

8. Temperature a) Less heat to be generated 3

List of metrics for brake callipers

Black box model

Activity diagram

Purchase /Get

With Bicycle Install in

the cycle

Disposal

Wash

Return From

Braking

Braking

Prepare to

wash & clean

Prepare to

Brake

Clean The

brake

Return from

washing/cleaning

Home

position

Design drivers

Profitable Operating Condition

Braking Condition

Bowden Cables Callipers

Effort

Braking

Weight

Ease of

setup

Profit

Sales

Manufacturing

Cost

FAST METHOD

C

Hold Pads in

position

Actuate

tension in

brake wire

Hand force

Press pads Generate

friction

Reduce

friction

Generate

friction

Apply brakes Apply force Stop Bicycle Actual force

Convert

mechanical

force to

friction

Reduce noise

Create

aesthetic

appeal

Support

structure

Ergonomic

system

Reduce

friction

Subtract and Operate applied to Brake callipers

Calliper Brake pad Adjusting barrel Brake lever Anchor bolt

No provision for

holding brake pads

No defined way of

stopping

No provision for

lengthening and

shortening of cable

wire

Mechanical

squeezing is not

converted to tension

No way to hold the

cable wire in place

No way of

transmitting force

to rim

No way of holding

against the rim

No way of adjusting

slack when brake

shoes wear down.

No way of pulling

the callipers

Toe-in will not be

achieved

No provision for

reducing impact

noise

Indexing not

possible on geared

shifting cables

Slow forward

motion of bicycle

can be achieved

No prevention of

squeaking

Safety issues will

be failed

Aesthetic

appearance reduced

Difficult to clean

undefined body

Function tree for brake callipers

Stopping Of Bicycle

Hold Provide

Stoppage Apply Brakes Input Signal Input Force

Accept

Force

Convert Force

To friction

Accept

Signal

Transmit

Signal

Contain

vibrations

Support

Assembly

Control Force

Apply

Brakes

Secure

Assembly

Hold force

Transmit

force

Hold

rim

Adjust

position

Control

rotation

Hold

signal

Control

signal

Support

assembly

Dampen

vibrations

Adjust

assembly

Apply Friction

On pads

Generate noise

Reduce noise

Control

tension in

cable

Drag

lever

Release

lever

Technology road map

Time

Time

Spoon

brakes

Brake

type

Duck

brakes

Rim

brakes

Drum

brakes

Disc

brakes

Rim brake

type

Side

pull

Centre

pull

V

brakes

Delta

brakes

Drag

brakes

Brake

levers

Standard pull levers Long pull levers

Operation

type Rod actuated Bowden cable actuated

Pivot

Config.

Single pivot Dual pivot

Actuation

mechanisms Mechanical Hydraulic Dual type

Functional

elements Technologies

Cost scenario

Category Projected cost($) Cost per product($/clipper)

Labour costs Large calliper: Assembly Handling

$300,000 $225,000

$9 $6

Total $525,000 $15 (avg. calliper)

Fabrication costs Large calliper: Materials Parts Tooling

$390,400 $250,300 $10,000

$20 $9 $5

Total $650,700 $34 (avg.calliper)

Installation costs Large calliper: Installation cost

$10,000

$6 (avg. calliper)

Engineering costs

Avg. 10 weeks per product $115,000 $12 (avg. calliper)

Maintenance cost Avg.1 time per week $5,000 $3 (avg. calliper)

Total cost $1305,700 $70 (avg.calliper)

Product life cycle

S-curve

Concept generation

Convert Mechanical

Force To Friction

Accumulate

Energy

Apply Braking

Force to Wheel

Liquid/oil

Water/oil

Bowden Cable

Piston

Single sImp

Liquid/oil

Water/Oil

Bowden Cables

Piston

Piston

Electrical Load

Single Impact

Multiple Impact

Cables Electro Magnet

Convert Mechanical

Force To Friction

Accumulate

Energy

Apply Braking

Force to

Wheel

Liquid/oil

Water/oil

Bowden Cable

Water/Oil

Bowden Cables

Piston

Electrical

Push Brake

Liquid/Oil Piston

Multiple Impact

Cables

Electro Magnet

Concept Screening(Pugh’s Method))))

Selection Criteria Rim Brakes Electro -Magnetic Brakes

Pneumatic Hydraulic Disc Brakes BrakesBrakes

Ease of Setup

0 0 0 - 0

Light Weight

0 - + - 0

Strong Braking

0 + - 0 +

Good Response

0 0 - + +

Compact

0 - 0 - 0

Effective Force Transmission 0 + - + +

Sum +’s 0 2 1 2 3

Sum 0`s 6 1 3 1 1

Sum –‘s 0 2 3 3 0

Net Score 0 0 -2 -1 3

Rank 2 2 4 3 1

Continue? Yes Revise No Combine Yes

Conclusion

We have done design of brake callipers for bicycles using product design techniques. The

customer’s needs, cost scenario, constraints, specifications are taken into consideration.

Through this study we found that Electromagnetic brakes are good prospect, more study is

required in this field to implement them on a full-fledged basis. More experimentation needs

to be done to make them more compact.

References

1) Design Websites

2) Text book on Machine design by V.B.Bhandari.

3) Bicycle brake callipers Wikipedia

4) Manufacturers catalogue of Dawson India Pvt ltd

5) http://engin1000.pbworks.com/w/page/18942694/ElectromagneticBicycleBrake