Bicycle Braking Systems

hertz Braking Systems Year 11 engineering Studies Merewether High initiate Nathan Dunshea 29/06/2012 Abstract In this report a relation of triad Braking transcriptions mensurate, Drum and platter leave alone be do on a variety of aras including * * Effectiveness * Performance * Features * Materials * frictional Components * Difference from comparable to(predicate) railcar brasss An Orthogonal and Pictorial drawing will also be r decisionerd on a selected section of one of the braking governance of ruless being compargond. Introduction Bicycle Braking governances atomic number 18 a means of which we ar able to halt the movement of a cycle through the expulsion of kinetic cipher.The Kinetic potential energy that is present in a travel oscillation is converted in to 3 contrastive forms of energy mania, sound and light. This is come ine through the subway system of a wheel to move when a pasture pasture halt applies a encounteral advertise against the spinning movement of a wheel. Three different types of halt be gener tot all(prenominal)yy practice on bicycles today the measure out, Drum and phonograph record systems. These ternion popular braking systems book their profess unique set of advantages and disadvantages that pack the population to purchase them. 2 mensurate stop diagram Calliper brake Diagram 3 disk Brake Diagram 3 track record Brake Diagram 4 Drum Brake Diagram 4 Drum Brake Diagram Procedure I use the Internet to research pictures, articles and suppliers of Braking systems in nine to access the appropriate tuition needed for this report. Results Effectiveness, Performance, Features Comparison Effectiveness 10 Cross-Section of a bicycle beat up brake 10 Cross-Section of a bicycle get brake The effectiveness of these Braking systems will be a measure of their qualification to answer over a period of time.It is necessary for these brake non to just perform intumescehead once, but over legi on(predicate) instances, including moments of firmly excessive braking. In todays modern bicycle, m any(prenominal) things will affect the braking systems dexterity to be effective. The weather, shake up and tear over some(prenominal) uses, as well as the type of braking taking place endure all squander untoward effects on brake. Drum stop are non the well-nigh popular style of brake for a bicycle. This could be accredited to their effectiveness over time compared to both mensurate halt and track record brake system. Drum stop are typically truly heavy, complicated to perform sustainment on and are a lot playing range to brake fading.Break fading sack up be defined as the expiration of braking force able to be exerted by the braking system at any point, and this often happens due to over conflagrateing as a result of concordant hard braking. Drum brakes are unable to dissipate light up anywhere near as efficiently as disk brakes as the frictional forces tha t turn kinetic energy into heat are all enclosed in spite of appearance the arise itself, which is often housed at the hub of the wheel. In fact, many companies have been forced to put warning labels on their hubs to collide with sure children arent unaware of the heat generated, and subsequently burn themselves.This makes them specially susceptible to brake fading, roundthing that both disk and mensurate brakes dont have a great problem with. In adverse weather conditions, the beat brake can show of its unique plus both the phonograph recording and measure brake does not have. The Drum brake is fully enclosed, and therefore is not affected by rain, mud and separate substances that may impede the frictional force exerted on the wheel. 12 phonograph record brake to be fitted to a Mountain Bike 12 track record brake to be fitted to a Mountain Bike Disc Brakes are precise popular on Mountain Bikes, which require cryptic wheels and are often subject to muddy terrain.Bec ause the disc brake is attach to the hub, a certain clearance from the ground is maintained at all times, mainly keeping mud from obstructing the pads and disc. If water is to get stuck on a crusheder floor a disc brakes pad, there are generally holes through which it can quickly escape so to not compromise the friction produced in the system. Touring bikes have been cognize to prefer disc brakes to types of calliper brakes, as the big journeys and significant use of brakes would not wear out the rim as they do using a calliper brakes system.The typical Disc Brake system is a in truth adaptable structure as it can perform divulge than Calliper Brakes in the mud, rain and snow as the coefficient of friction isnt as at risk of contaminants disturbing the system. Disc brakes are also little prone to brake fading when subject to long periods of braking pressure, as they are actually good at cooling protrude compared to drum and calliper brakes. A disk brake is also slight lik ely to cause a popped tyre, with the heat not being dissipated directly into the tyre as in calliper brakes. 14 Shimano Bicycle Caliper Brake 14 Shimano Bicycle Caliper BrakeCalliper Brakes are generally the most mutual of the braking system for the everyday bicycle. Excluding the original be after quality of the equipment and strongs, calliper brakes are often affected in general by the moisture that is on the rim, as that will significantly kibosh the ability to stop. Tyre thickness can also pose a problem to the calliper braking system, as the arms will be under greater flexion, thus lessening brake effectiveness. However, the Calliper brake system is effective on the average road bike and is the simplest and easiest to perform maintenance on of all three originations.This system also has a very big mechanical advantage, meaning very little motility has to be put in by the sit aroundr in order to properly apply the brakes. Calliper brakes are also by far the ligh render and least expensive, making them popular among non-competitive riders, with most road bikes lock up come fitted with this system. Performance The performance of a braking system is based on the raw filet forefinger and ability for one maven use. This comparison will be based purely on lemniscus advocator and performance, disregarding things much(prenominal) as * Weight of system * Weather/Terrain Brake Fading * Heat Dissipation The Disc Brake is said to have the grea stress tenia power, and therefore rears least fillet distance, of all three systems. This means they are often fitted to competitive riders bikes, because they are often handout a higher cannonball along and therefore need the greater stopping power that the disc brake provides compared to that of the drum and calliper braking system. In a report By Guy Kesteven for UK organisation What Mountain Bike, a variety of disc brakes were tried and true from many different manufacturers to test the power of each system.The test was performed as follows All the brakes were tested with a 180mm rotor and a 50Nm force on the prise (1N is the meat of force required to accelerate 1kg at 1m/s2), with the stock pads. To fully hunch forward in the rotors and pads, the brakes were given 60 one-second pulls at 15km/h, followed by 30 two-second pulls at 20km/h. After a 30-second cooling-down period, the testing began. With the wheel spinning at 30km/h, each brake was applied for three seconds and then left to retrieve for 10 seconds. This cycle was repeated 15 times. The results were then averaged out to provide a single power rating. Guy Kesteven What Mountain Bike. After the test had been completed, the Formula R0 disc braking system had the superior power of all 33 separate tested. It was found to have a power of 124 Nm when stopping, which is follow to 12. 645 kilogram-force meters. Calliper Brakes have one of the best designs in wrong of their Mechanical Advantage. Very little effort has to be put in by the user to have the brakes perform as well as possible. Disc Brakes have an boilersuit stopping power advantage over the general calliper brake, however some versions of the calliper brake have a greater stopping power than the drum brake design.With the huge variety of designs in the field of Calliper Brakes, stopping power can range from quite poor to very high. An pillow slip of this stopping power is the test carried out by Matt Pacocha in the June 2009 edition of Velo bran-news. A group of Bicycle Calliper brakes were to be tested to measure their stopping power This test was performed on a flat, windless road. For each brake, the rider accelerated to 40km/hr then grabbed the brakes hard on a pre-determined mark and recorded stopping distance.This test was performed 10 times for each brake, and the stopping distances were averaged. Matt Pacocha Velonews. At the end of the test, the Shimano 7900 dual pivot calliper brake was found to have the greatest braki ng force, with the shortest stopping distance of 7. 18 metres. It was also found that the average slowing of the bicycle was 8. 59 m/s2, whilst the greatest deceleration was recorded at 10. 35 m/s2 (Over 1 G-force). Drum Brakes are less powerful than the disc brake, and therefore have a greater stopping distance in normal, controlled conditions.Compared to Calliper brakes it is not clear-cut which has a better stopping distance, as there are many different versions of each type of brake to choose from. However, it is said that the modern drum brake is able to provide a much smoother, more trusty deceleration than the majority of calliper brake systems. Features Each of these braking systems have their own features which help to enhance the ability to stop the movement of a bicycle. Whilst some of these advantages are purely performance based, others may have features that are efficient or maintenance friendly.One of the most meaning(a) features in the success of the disc brake i s its ability to dissipate the heat generated from the frictional forces. Disc brakes are out in the open air with a adult surface area, meaning the cooling process happens more quickly and efficiently. other important, yet by chance underestimated feature of the disc brake is its positioning. Disc brakes are well away from the tyres and ground, thus creating distance mingled with the braking system and mud, dirt and other potential environmental interferences.Drum brakes however, are certainly the best in resisting those environmental factors. As the braking mechanism itself is housed within a shell of sorts, no amount of weather can have an adverse effect on the ability of the drum brake to perform its task. Once storeed, drum brake system is also very low maintenance, and often doesnt have to be managed again until a new wheel is needed. despite this, Drum Brakes can be a hassle if maintenance must occur, as they can be difficult to access because of the shell it is housed in. Calliper Brakes are generally the cheapest of the three designs available.As they are often mounted to the bicycle at one single point, accessing the brake pads and cables is made much easier than the other systems. Another feature that is helpful on the majority of road bikes with calliper brake systems is the quick stretch out mechanism. This feature is designed as to loosen the brake system nice so the wheel can be removed without having to mess close to with loosening brake cables as well. Materials used for construction and frictional components Brake Pads are perhaps the most important part of both the Disc and Calliper braking systems.The brake pad is generally made from a product that possesses a moderately high coefficient of friction, but also depends on the materials ability to absorb and dissipate the heat produced in the process of braking. If these criteria can be met without having a negative impact on overall braking performance, an appropriate material has been found. In years gone by, an asbestos based compound was the most common material from which brake pads would be made, however because of the toxic nature of asbestos that work no longer allowed. The modern bicycle Brake Pad is enerally made from rubber compound. The rims on bicycles directly affect the performance of the Calliper braking Systems. more or less bike rims today are made from an aluminium alloy, which provide a coefficient of friction when in contact with the rubber involved of the brake pads of approximately 0. 4. Other materials, such as various Carbon vanes, have tardily become more popular as they are light and aerodynamic. However, they do not provide a very good frictional force between the everyday brake pad, and so other materials are often preferred by the everyday cyclist.Calliper brake systems also have brake cables that transfer the motion actuated by the rider from the brake lever to the braking system itself. These brake cables are made from th in wire blade that has been braided in concert to improve its tensile strength and ability to perform. The Disc in the Disk brake system is an integral part of the bicycles stopping power. The Brake pad (rubber composite) must have a high plenty coefficient of friction when applied to the disc to halt movement with damaging the surface.To provide this, the disc is made from surface, with stainless steel being popular among hole bikes. A brake drum has an outer shell in which the braking system itself is contained. This outer shell is subject to weathering from the outside and heat from within. With this in mid, cast iron is generally the material chosen as it can cope with these two burdens other materials could falter under. The shoes of the Drum brake are the move that push outwards to produce the frictional forces needed in the brake design.These brake shoes are generally made when two pieces of planer steel are welded together. After they are welded together, the frictional material known as brake lining is connected on to the sheet steel with either adhesive resin or other means such as a rivet. It is also important to remember that the rubber composite of bicycle tyres also has frictional forces acting from the material it is rolling on. For instance, if a cyclist was locomote along a concrete surface, the coefficient of friction would be 0. 8, much higher than that of rubber or brake lining to metal (0. ). Thankfully, the relatively light weight of the human body compared to the force exerted by our mechanical braking systems allows us to still move along these surfaces. (FF = ? RN) How they differ from comparable car systems On most bicycles, the braking systems installed will often be very simplistic and just there to do the job. Most will have the same type of brake on both calculate and certify wheel, with the braking of the bike mostly relying on human action with levers and cables, as well as the mechanical advantage some of these design s provide.However, when upgrading these systems to work on a much heavier vehicle such as a car, many things can assortment. It is not uncommon to have different types of brakes on the summit and back set of wheels, and hydraulics become a very important part of stopping your car. In todays modern designs, at least one set Disk Brakes are fitted to close to every car on the road. Disk Brakes are the most effective type of braking system that we could fit to our cars, however, it is still common for the front brakes to be disk, but the rear to be drum brakes.Drum brakes can be used as the parking brake, and by adapted them to the rear of the car, companies can save money by not having to install another braking system. The Disc Brake in a car is simply in a much larger scale than that of a bicycle. Despite this, the two systems are very similar in the basic design concept. Strength of this part however, must be much greater when installed in an Automobile. Winnard & Sons Ltd, a company based in the UK that deals with commercial vehicle braking components, has a guideline to the tensile strength on the brake contact surfaces of their products. signpost tensile strength on test pieces machined from brake drum/disc contact faces 241 N/mm2 European prerequisite minimum 35,000 psi Amercian Requirement minimum Winnard & Sons Ltd Brake Disc and Brake Drum Material precondition The materials used in the brake pads of both the disk and calliper brakes are different when they are made for cars. When halting the momentum of a car, the brake pad is put under a much greater force than when stopping a bicycle. This is due to a number of things, including the speed at which the car is travelling and the mass of the vehicle, both of which are generally higher in cars.The metals used are usually steel, copper or brass fibres, as well as a mixture of many different composites including graphite, iron oxide, glass fibres, phosphate and rubber that are bonded together with a resin of phenol formaldehyde. The metals that are added help to increase conduct span by improving the ability of the compound to dissipate heat at high speeds. The complexity of all three designs is greatly heightened when moving from bicycle to motor vehicle. One asp viperect of Motor Vehicle braking that creates duplication pressure is the hydraulic action of the brakes.Hydraulics rely on brake fluid, typically containing ethylene glycol, to transfer pressure from the controlling unit to the brake mechanism. In a motor vehicle, drum brakes often serve a detail purpose that they would be useless for when installed on a bicycle the park brake. As I stated earlier, these Drum brakes are fitted to the rear wheels and can save companies significant amounts of money by not having to install a completely separate parking brake. As this asset of an emergency brake is vital to a larger system, not only are they more common in cars, but they must also be bigger and exert a grea ter force.These three types of braking systems predominate the same principles when applied to a greater size vehicle in a motor car, however many things must change to prevail these increased forces. Conclusion Each of these three braking systems are often used by a specific type of bicycle with a specific need. An example of this is Disc brakes being preferred by those who ride either Mountain or Touring bikes. As shown by the two field tests referenced in this report, completed by Velonews and What Mountain Bike, both Calliper brakes and disc brakes both have a very big potential to have immense stopping power.But to have that stopping power, the proper materials with appropriate frictional forces would have had to been in place. At the irresponsible top of the line models, every little detail is considered, i. e. * * Weight * Frictional Forces * Materials * Angle * Type of System It was also discovered that as we musical passage from bicycle to car braking systems, many thi ngs must be neutered. Although the basic engineering science principles are often the same, there are many variables that are altered to improve to braking systems to cope with the extra forces exerted by a motor vehicle.For example, the change in materials of brake pads to accommodate the much more intense levels of heat being produced when heavy braking is taking place. I believe this report reveals that the braking system you own can make a big difference on effectiveness and performance. The features, materials used and frictional forces in play can all be positive or negative depending on the type of riding taking place. Recommendations I recommend selecting one of these three types of braking systems based on what their use in the long run will be.If you plan to use the bike for competitive purposes when increased stopping power is necessary, I would conjure up purchasing a Disc brake system. However, if the bike is simply for leisure, perhaps the more cost effective Callip er Brake system would better suit. If you are planning to ride in muddy areas where the possibility of substances interfering with the frictional forces throughout the braking system, the fully enclosed drum brake system could be the appropriate option. However, if you wish to simply have the greatest overall stopping power, I would recommend a Disk Brake system be installed. The most mportant thing to remember is that every situation is unique, and to do research in order to attain the correct brake for your needs. 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