Front suspension system of motorcycle

Front rest system of travelcycleCHAPTER 1 INTRODUCTION1.1 AIMSThe main aim of this project is to radiation diagram and analyse of a attend foramen system of cycle. The designing and modelling of the tell is done using Pro-Engineer (wildfire-4) and Stress analysis is undertaken by Ansys 11 softw bes.1.2 OBJECTIVESTo tucker out aw ar of deformations caused collect to application of pasture brakes to the disunite of the front open frame systemTo demonstrate detailed view of occasioning of fork To show universe of various kind of front suspension systems used in motorcyclesEvolution of front suspension systemsTo verify the benefits and the flaws of different front suspension systems, used considerably(p) from the old age to modern ageTo illustrate how the motorcycle keeps its balance and analyzing the factors that come into wanton away while ridingApplication of vibration modes, on suspension system of a motorcycle while riding.1.3 INTRODUCTION TO MOTORCYCLE FRONT SUSPEN SION SYSTEMA Motorcycle front fork connects a turn everyplace and axle to its frame, by way of a pair of triple steers. The roll is steered by handle touchstones which atomic number 18 attached to the triple tree and alike brake is provided to retard or stop the acceleration of the bike. There atomic number 18 loads of critical geometric parameters such as Rake and Trail which are streng because by the fork and its attachment daubs on the frame, which usually play for handling and riding and dives as well during braking. telescopic forks The term Telescopic forks is defined because the thermionic supplys err in and out of the body they are Telescoping. The f number portion generally called as crotch furnishs (Male tubes) slides inside the fork bodies (Female tubes), which are pass up social function of the forks. everyplace more than century years of motorcycle improvement, different variety of front form arrangements have been attempted but some of them are stil l live available nowadays. The most common form of front suspension for motorcycle now days are the Telescopic fork Nimbus was the first shaper to produce a motorcycle with hydraulically damped telescopic forks in 1934.Early front suspension designs were used frames with springs. Greeves, a British manufacturer used a variate of swinging arm for front suspension on their motocross design and also a single sided version suspension system is used in motor scooters such as the Vespa. Suspension system is equipped with large hydraulic traumatise absorbers with internal coil springs. The main work of the shock absorbers is to allow the front wheel to react to imperfections in the road while isolating the rest of the motorcycle from that motion. The Upper part (Top yoke) of the forks is connected to the motorcycles frame in triple tree clamp, which allows the forks to be turned while charge the bike. The Lower part (Bottom yoke) is fixed to the front axle around which front wheel ro tates. The fork tubes should be smooth and reflect finish, so as to seal the fork oil. Some fork tubes found on the slay-road motorcycles are covered with plastic protective sleeves called as Gaiters. The forks are constructed any of the conventional right-side-up or sliding -female configuration, or the Upside- down(a) pat(p) or Sliding -male configuration. In Both the cases, a cylindrical tube or piston sided axially within the cylindrical cylinder. Trail and Rake Trail is the measurement, on the strand, from a point which is projected through direct axis of rotation to the centre of the tyres relate patch below the axle. Trail determines the self centring stability of the steering as well. The triple clamps provide ethical lateral offset that the forks clear the sides of the front tyre. usually Triple clamps are introduced to provide some measure of longitudinal offset as well, to alter the racecourse. Trail impacts directly on the steering stability of the motorcycle and its return-to-center hurl. The trail is much affected by rake .Rake is defined as the rake between the vertical and steering axis. The steeper rake reduces the trail and trail itself is also affected by the longitudinal fork offset. More offset decreases the trail. The trail is also affected by axle offset. The trail increases in the case if the axle is joined to the forks in front of their centre. Ride height Sometimes rider desires to increase or decrease trail to change the steering feel so as to improve steering swiftness, or to eliminate advanced-speed shake, or to reduce a front end push. Ride height is simply defined as the forks extending up through the triple clamp. Decreasing the ride height by raising the forks farther through triple clamps in reality steepens the rake, which results in change magnitude the trail. Alter in trail causes the effects to the rider to his ride height adjustments.CHAPTER 2 LITERATURE REVIEWMotorcycles were first developed out of the bicycle frame, which for certain is rigid. Suspension systems were progressed over the years after critical researchers to filter out ground disturbances in more efficient ways.CHAPTER 33.2 FORK FUNCTIONINGThe weights are transmitted from inner tube to the outer tube or vice versa through the slider bushes which are placed between the two tubes. The bushes used for the good fork are critical because it should have a very low coefficient of friction as well as mounting tolerance. The system smoothness is exclusively estimateent upon the friction forces developed during sliding relocations as well as on the amount of stiction.The stiction is at uttermost at Moto incipiente ,,When the initiation of the scatment occurs between the surfaces. This stage is called as static friction. In Designing and fabrication of the slider bushes, the problem of sliding friction always stand for a weak point in the front fork of the vehicle. If we compare it, for example, to the rear suspension in which there is practically no sliding imputable to the displacements consists of rotations around the bearings. The suspension settings rear be achieved by the callosity of the spring, as well as the damping provided by the hydraulic part, to which is added the resistance given by the sliding friction. It is difficult to predict what the suspension behaviour operates and its proper functioning is taking cared by the availability of friction. In the design stage, limiting friction forces require that the loads on the bushes be minimized, boosting movement of the unit. When the fork is extended fully, only a small segment of the slider tube enters inside the sleeve. Hence at this stage its overlap is reduced to a minimum. This is also constitutes the least rigid configuration of the whole system. At the end of the travel, as a substitute of the fork tube overlap extreme thereof maintaining the stiffness.3.3 FORK STRESSES AND DEFORMATIONSCertain forces acts on the fork leg while th e vehicle is in motion. Two cases can be considered which helps us to derive fork stresses as well as deformation. They are (i) Fork flexure out-of-pocket to vertical loadsThe flexure due to vertical loads involves the stresses which act on by weight of the motorcycle plus rider. Also stresses tend to develop due to road surface irregularities such as through potholes, steps ridges, etc. genuinely these stresses are considered negligible for example, If we travel in the city at The Moment of flexure or Bending moment is generated when the vertical load is finally utilise to the wheel. The moment of flexure or bending moment gradually increases as the fork is inclined. When with the kindred force applied, the bending moment testament reach to the maximum in the case of fork extended fully and vice versa the bending moment pull up stakes be minimum with the maximum compression. Therefore the values pull up stakes as the changes occur in the arm of the force applied. The stress es are less when the slider bushes are closer to the wheel spindle and are expected to function better. When the rider passing over dip holes in the ground in the road surface, the vertical loads can attempt very laid-back values, thusly the frame structure has to be stiff enough to avoid excessive deformation and simultaneously it should have the capability to absorb all the immediate bumps whe neer the suspension bottoms out. At the front end the area, steering query tube receives the heavy stress .whereas, at the rear end connecting rods as well as the shock mounting come under the greater stress. When the motorcycle is stationary, the load values that appear during normal use are two to three times as big as static loads which are normally acting on the wheels. If we consider a medium powered street bike which is loving moving on a bumpy road with a high speed and if the wheel bounce on hole then the stress exerted on the structure may be hundred of kilos or more. Maximum loa d values can take place when the off-street bikes jumps and cross over the obstacles.(ii) Fork flexure due to braking forceAs it is the known fact that when braking force is applied to the wheel, then it is obvious to the wheel, experiencing the deformations upon different circumstances of road. In this case, Bending will greater as the length of the fork is high. The exceedingly point outable point of interest is that the deformation due to vertical forces is opposite to the deformation due to the braking force. In the previous case we observed that, during braking, because of the weight transfer effect, the front load increases i.e. there cant be a braking force without an increase in vertical load. When the brakes are applied to the bike then some strong longitudinal forces are created, giving cut to bending moment that gets stronger as it rises from the ground to the steering head tube, finally transmitted to the whole frame. The steering head tube experiences the strongest m oment. The steering head tube is the point with the least depth of section, which is the major plane of stress. cod to this considerations observed, detailed research and study has undergone to give the actual design dimensions of the whole steering tube. On this part of flexure happens during the big hurtle of acceleration would definitely cause trail variation. When the braking stress dies out for example when entering a corner, there would be an annoying elastic rebound litigate in response. Meanwhile the rear fork doesnt experience much stress during braking as front fork does. The above two effects (i) Flexure due to vertical load as well as (ii) Flexure due to braking force will certainly oppose each other and within the slowdown range of characteristics of motorcycle, depending upon Cg height, wheel base and fork inclination. In general fork flexing during braking is not as severe as one might think.Deformation due to torsional forcesThe twisting forces which derived are as followsThe bond is poor between the fork axis and equilibrium forcesThe components of equilibrium forces upright to the fork axis and out of alignment with itThe couple which applied by the rider to the steering head.The resultant deformation is express to be very harmful for handling because the wheel does not answer properly according to the direction of control set by the rider of the vehicle.Effect of deformation on functionalityIt is clear slap-up away that the presence of fork deformation makes the proper sliding inside one another more complex to the point of potentially impeding it. When the bike is in motion, the deformation is at highest at most critical circumstances such as brake application and corner entry.3.4 DIFFERENT DESIGN TYPES OF FRONT SUSPENSION SYSTEMTelescopic forks are mainly classified into two kinds which are used in practical applications in daily routine life. They areTraditional or trite which is equipped with an internal tube, the one with sma ller diameter in the upper postion, fixed to the frame.Upside shore or Inverted which is equipped with internal tube in the lower position, which is fixed to the frame.The hydraulic as well as elastic fundamentals of these kinds can be simply comparable in do to know the different responses of the same motorcycle equipped with two distinct types of forks. There are some manufacturers whom have created a Cartridge containing the hydraulic part which can be easily mounted onto each of the applications being tested. The first telescopic fork prototypes was designed right after the turn World War, were rigid out with little attention as to whether they were in traditional or upside down form. In the sixties, the majority of the forks produced was traditional type whereas Upside down design came into the existence at the beginning of the eighties. The upside down design was popularised back into circulation of sport bike applications. Contrast between Traditional and Upside Down form of telescopic forks Benefits of Tradional formLess number of components, given that the wheel attachments and axle lug derive directly out of lower stanchion which also keeps weight downUnsprung upsurge weight is slightly reducedTubes slides in areas that are more protected from bumps and dirt.Benefits of Upside down formIt has superior torsional stiffness with the same weight, where the tube has larger diameter and is positioned in upper area, which deals with greater stress from the bending momentStrong attachment between the tubes and the triple clamps which have large tube diameters.The above comparison between the two applications says that one is absolutely better than other. So, in this case upside down layout presents more advantages in the terms of stiffness which makes ideal for some sport-oriented applications. Both the applications Traditional as well as Upside down forks are characterized by Different stiffnesssDifferent weight scatteringDifferent values of unsprung weightDifferent center of gravity heights between the steering and the groundDifferent values of inertia around the steering head axis. There are some other types of unconventional fork types and can be classified into the groups. They areSwinging front fork or PivotedParallelogram connexionage or GirdersStraight line slider make itsParalever tieage.a) Swinging front fork This type of fork was in particular used on the earliest bike models and it is a very simple construction stem. In practical, it reproduces the geometry of the rear fork, along with a n arm that usually rests on a fulcrum which is placed on the steering column, making the fork rotate in one piece along with the steering head. Depending upon whether the arm is compressed or extended during braking, track link or trailing link front forks are discovered. In both the cases of the forks, the layout may be seen to be symmetrical to the head angle with two ordnance store or it may consist of only one arm. For scoo ter models, Pivoted front fork suspension is adopted, but they are almost rare when coming to high performance vehicles. The main characteristics of swinging front fork suspension system are as follows. In Smoothness ,They are very smooth when the rotations are assured by rolling bearings eliminating stictionWhen the matter comes to design construction, the stiffness may be better or sometimes worst.The connecting rod linkage systems have never been used to gain progressive rates it is easy enough to obtain progressive spring rather.The inertia is high around the steering axis and the unsprung pile have moderate weights which are totally dependent upon the type of construction used for the forksIf we compare both leading link as well as trailing link, it will be the great point of interest. Leading linkIn mid 1950s, the world champion Moto Guzzis which are the best handling cannonball along machines of their period, were installed with leading link. The leading link consist of a t ubular or pressed steel structure which connects the steering column in the link pivots and slot in for the suspension struts. The think appear to be independent or formed by a single U-shaped loop around the back of the wheel. In the case of the links separation, their resistance to independent movement as in the type of telescopic fork, depends upon the rigidity if their attachment to the wheel. If the wheel has large- diameter spindle then it also haves large wheel bearing and the most convenient and efficient method is a loop behind the wheel and a smaller -diameter spindle. Benefits of leading fork are as followsQuality of detail designPossibility of greater rigidity.Greater stability on the forkPrecise control over the steering.The lack of stiction enhances the sensitivity to the small undulations and also any degree of anti -dive under heavy braking. The wheel has precise path which usually depends on the telling heights of the wheel spindle and link pivots. Because of the curve shaped, these forks are highly unsuited for the large movements which are usually used on modern off road machines. In the leading link during braking the anti-dive behaviour can be seen. The anti dive behaviour tries to extend the suspension, in the case of application of braking force that is applied to the fork .The Anti -dive behaviour can be prevented by ameliorate brake calliper to a torque arm which is connected to the steering. In this case, spontaneous center of rotation may be positioned so as to create anti-dive behaviour.Trailing linkThe trailing link differs from that of leading link in many ways like the link pivots of the wheel spindle are ahead, not behind. The demerit of this kind of fork is higher steering inertia, since the bulk of the mass is relatively far from the steering axis, which has an effect that partially offset by the smaller amount of material required to reach the pivots. In the trailing link during braking, the pro-dive effect occurs which i s quite similar to the traditional fork .In this case as well brake torque arm will be introduced along with fixing brake callipers in order to get the proper effect when braking.b) Parallelogram linkage or GirdersGirder forks are widely used now a days which is also considered for their superior steering. Due to friction dampers, the performance was generally limited and very crude by current hydraulic standards. The links which operates the suspension system were shortly and due to this kind of forks are very much suitable for small amount of suspension movement. One of the forks namely Vincent Girdaulic was most sophisticated. It consists of light -alloy blades and one-piece upper as well as lower link assemblies. The trail for this fork was readily adjustable. Springs were adjusted in the long telescopic tubes, behind the uprights, but the hydraulic damper was separate, mounted in front of the head stock. The lateral stiffness was boosted by a plate which will bridge the front of the blades. Hydraulic damping is active against suspension movement and also to damp out steering excursions, a damper was used. The most recently released linkage designs comes under this category. The main characteristics of the parallelogram linkage are as followsThe smoothness of the fork is outstanding, since sliding friction is substituted by rolling friction i.e. Sliding movements are kindly replaced by rotations around the roller bearingsIt has got sufficient amount of stiffness enhanced by the design constructionThe progressive rate of the suspension can be incorporatedThe trajectory control is excellent which is highly dependent on type of fork used. It is possible to have different types of wheel trajectories with the help of parallelogram linkage system. The trajectory can be considered perpendicular to the ground, maintaining the same wheel base, or to obtain certain degree of anti-dive it may be inclined forward, in the beginning phrase.The trail control is good. In this case, it is highly possible to create constant trail geometry with varying travel .It can be increased or decreased according to riding behaviour of the vehicle.Depending upon the fork design, the unsprung weigh could be less but the net weight of the suspension remains constant.The most popular design solutions used in automotive intentness are as followsSolution (a)In this type of solution, the fork legs are allowed longer along with mounting brake callipers. Like single sided rear fork, the links that hold the wheel can also be asymmetrical. The steering is controlled by positioned links.Solution (b)It is rarely employed and characterized by high steering masses and certain inertia, less bulk and steering control is high.Section (c)This type is rarely employed. The leg length is reduced to make large wheel travel. Kinematic loads will be large with such a short fork legs.Solution (d)This kind of solution is generally employed for light motorcycles and has been introduc ed right after the Second World War. The steering control is good but it imposes limits on the steering mass size and on trajectories available to the wheel. Because the links are located at certain altitude, the stresses on the links due ot the forces are very tough.Solution (e)This kind of solution has been introduced in most advanced applications. In general, it unites all the advantages offered by girder solutions. When it comes to design of the fork, it experiences some drawbacks in the terms of the looks. The horizontal arms have to be long enough to allow the wheel to be steered. Due to this factor, it could be a strong limit the maximum steering angle value, which usually restricting the use of this solution to the street bikes. The links controls the steering offering the surmisal to position the shock absorber in areas that make the mountings powerful and fabrication is easy. Through connecting rod system, the steering control may be easily constructed.Solution (f)This so lution is quite similar to the solution (e), but it does not allow offset of the wheel with respect to the steering head axis or zero offset. Due to the large diameter bearings in order to house the steering kingpin, the wheel hub center becomes complicated.(c) Straight -line slider bearsStraight-line slider guides are especially regarded by the same geometry as the rear fork when speaking about the controlling the trajectory of the point O point and trail are concerned. Practically, the cylindrical slider is replaced by a straight line slider but of rolling type. The classic shock absorber is represented as the damping element in this case, while rolling guide bearings are similar to ones used for highly developed mechanical machining work. The Advantages of Straight-line slider guides are as follows It enhances better smoothness It hails limited play as well as has got good stiffness The limitations of straight-line slide guides are as followsThe main problem is difficulty in pos itioning the two disc brakesAsymmetry-it gives rise to bothersome moment around the steering axis.(d) Paralever linkage This type of solution is generally considered as a corrupted parallelogram linkage system because, the upper linking bar is missing and also the suspension function is done by a slider derived from intermediary part that becomes a sort of fork. Advantages of paralever linkage system are as followsThe sliding motion in this case is simpler when compare it to standard forkThe transmission ratio is 11 in this case as the steering is directly connected to the tubes.Limitations of Paralever linkage are as follows It is more mechanically complex than a traditional fork and generally bulky due to the presence of horizontal arm.(e) mechanised anti-dive systemIn the field of racing, mechanical anti-dive type fork systems have been introduced to limit their tendency to front end dive. In this case, By means of a series of links, the braking force sustained by the brake call iper is transferred to the chasis, opposing its tendency to dive. The mechanical anti-dive system has been not recognized universally because of the following problems incurred.Making of brake callipers is difficult in this case which mounts rigid enough, with possible braking power loss and aswell as formation of micro-vibrations.The systems weight is highMoment of inertia is increased over the steering massesLess amount of effort have made in vehicles handling.(f) Hydraulic anti-dive systemMechanical anti dive system has been replaced by hydraulic-anti system. Hence they are increasingly rare. The hydraulic anti-system is totally based on the hydraulic braking usually when the brakes are applied, by blocking the passages. When the hydraulic brakes are made too strong thus it becomes difficult to absorb small irregularities in the road surface, especially during the complex way of entering the corner of the road.CHAPTER 4 STRAIGHT LINE MOTIONThe topic straight line motions deals w ith How the motorcycle keeps its balance analyzing the factors that come into play which can simply help the rider to maintain the motorcycle in a vertical and stable position while travelling. The factors that are responsible for maintaining the straight line motion path areInertia effectsgyroscopic effectsRighting effects.4.1 INERTIA set upThe product if mass multiplied by the pep pill of a body gives the quantity of motion of the body. Due to greater value of this is, the less influence external forces will have on trajectory. For example, lets assume that a motorcycle is travelling at high speed such as 100km/h then the vehicle also attains a upper of 10 km/h perpendicular to the original trajectory as shown in fig a. If the motorcycle moves at slower speed of 10km/h, then the same component velocity influenced by the gust of wind brings variation in the direction of travel as shown in fig b. Hence as the velocity increases, small directive variations orthogonal to original direction will bring smaller angular variation. Therefore, now we can state that the greater the forward velocity, the more difficult is to move the vehicle from its initial straight-line trajectory. The same concept can be applied to mass like heavier a body is the more it resists changes to its speed and direction. In the figure, Vint = initial velocity Vres = resultant velocity dV = variation in velocity = angular variation in velocity.4.2 GYROSCOPIC EFFECTSWhen every time a body spins rapidly on its axis and simultaneously is to set into rapid spin around a second axis is referred as gyroscopic effects or a moment that eventually acts around a third axis perpendicular to the other two. In routine life, gyroscopic effects can be seen for example, a spinning of bicycle wheel in between ones hands illustrates gyroscopic effect. If the wheel is set to keep axially parallel to it and raise and lower the wheel straight up and down then we can notice no opposing action on our hands. Hence it can be said that the opposing vertical force is needed to perform the action will never be more than the weight of the wheel itself. Now in the succeeding(a) trial if the axis of the wheel is turned in clockwise motion around vertical axis, as if we were holding the steering handlebars. In this case, we will notice that our arms are affected by a couple that tends to rotate them around the longitudinal axis. From the following experiment, certain conclusions can be drawn Gyroscopic effects will be more when the wheel rotates faster The intensity of the reaction will differ obviously, if the axis is tilted faster or slower.4.3 RIGHTING EFFECTSThe parameter righting effects is profoundly influenced by the geometrical characteristics of the steering unit of the motorcycle. The correct combination of these factors gives positive results for the awareness of stability. Righting effects can be depend upon the following phenomenonsSteering axisRake angle (Castor)Trail4.3.1 Steer ing axisRegardless of structure of motorcycle suspension they are characterized by a front wheel suspension by a front wheel steering, because front wheel is free to rotate around the axis which is called as steering axis. In general, the steering axis in the bicycles is referred as Head angle and is measured clockwise from the horizontal when viewed from right hand side. A 90 head angle would be vertical. For example a 2007 Filmore, which was designed for the track with a head angle, varies right from 72.5 to 74 , depending upon frame structure and size.4.3.2 Rake angleIn the case of front suspension, it is very easy to identify steering axis especially in the telescopic fork because the steering axis coincides with the axis of the guide bearings inside the slider around which the fork rotates. This steering axis is present in all automotive type suspensions is inclined with respect to the vertical angle known as Rake angle. Rake angle is measured usually in degrees from zero. Inc lination of rake angle () If we increase the angle of the steering axis then we should also increase the value of trail. Usually the steeper the inclination of the rake angle, the motorcycle tends to be more stable directionally. Some grand prix bikes meant for free-enterprise(a) or sports oriented uses smaller rake angles such as little as 21 rake angle. custom made bikes have modified a steeper rake angle beginning from 28 and reaching 40.4.3.3 TrailThe Trail of the front suspension system is defined as the exceed between the point of intersection of the axis with the ground and the contact point of the front wheel w