Project Final
description
Transcript of 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