Tripod Steering for Better Maneuverability of Quad-Bike

Tripod Steering for Better Maneuverability of Quad-Bike

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  International Research Journalof Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 04 Issue: 12 | Dec-2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 6.171 | ISO 9001:2008 Certified Journal | Page 1462 Tripod Steering For Better Maneuverability of Quad-Bike Prajval Vaskar1, Gaurav Kadam2, Mohit kamble3, Prathamesh Sangelkar4 1,2,3,4 Department of Mechanical Engineering, SAOE Kondhwa. ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract – All terrain vehicles, as the name suggest, are designed to fulfill needs in rough terrain regions such as Hills, farms, borders etc, where on road vehicles can’t perform well. Steering mechanism must be designedconsideringtheoff-road conditions and should give better stability, maneuverability& minimum possible turning radius. Human comfort as well as steering effort is important parameter that should be considered while designing steering system. The objective of this paper is to use ‘Tripod Steering Mechanism’ (Bell Crank lever Steering Mechanism) for a quad bike .Rack & pinion is not suitable due to limiting steering ratio and use of handle bars over steering wheel. Bell crank lever is easy to design, manufacture and has comparatively less production cost. Key Words: Quad-Bike, Steering ratio, Creo, Ansys, Tripod plate. 1. INTRODUCTION Steering system is one of most important part of an automobile that is used to give directional stability to the vehicle. The basic aim of steering is to ensure thatthewheels are pointing in the desired directions. This is typically achieved by a series of linkages, rods, pivots and gears. [1] Ackerman Steering Mechanism is generally used in all vehicles. The significance of Ackermann geometry is to avoid the need for tires to slip sideways when following the path around a curve. The geometrical solution to this is for all wheels to have their axlesarranged asradii ofcircleswith a common centre point. As the rear wheels are fixed, this centre point must be on a line extended from the rear axle. Intersecting the axes of the front wheels on this line as well requires that the inside front wheel is turned, whensteering, through a greater angle than the outside wheel. [2] Among rack and pinion mechanism, steering box mechanism and tripod steering mechanism, tripod steering is suitable for quad bike because of the limiting steering ratio. The design was finalized using CREO 3.0 and tripod plates were analyzed in ANSYS 14.5. 2. DESIGN OF STEERING SYSTEM 2.1. Ackerman Principle Fig -1: Schematic diagram of Ackerman Steering Mechanism Ackerman principle states that all wheels should be rotated at one point. From the fig all the wheel have differentturning radius, this conclude that all 4 wheel will have different angular velocity. If vehicle is taking left turn the front right wheel will have highest angular velocity than othersasithas to cover larger distance & therefore its speed will be high. The left rear wheel will have lowest angular velocity so its speed will be low as compared to others. 2.2. Selection of parameters  Wheelbase : 44 inches  Front track width: 42 inches  Steering ratio :1  Steering effort : 20.66N  Kingpin offset : 70 mm  Kingpin inclination: 8°  Castor angle : 6°  Tire width : 5 inches Wheelbase and track width are selected consideringthe suspension geometry, handling & stability. As in quad bike handle bars are used instead of steering wheels, the steering ratio required is 1. Steering effort can be calculated analytically. The kingpin offset and inclination was decided by considering the packaging of wheel assembly inside the rim and scrub radius. Tire width is one of the important factors affecting steering effort. It should have enough contact patch and minimum steering effort. Castor angle is
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  International Research Journalof Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 04 Issue: 12 | Dec-2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 6.171 | ISO 9001:2008 Certified Journal | Page 1463 selected such a way that it gives optimum self alignment torque for better handling. 2.3. Tripod Dimensions Iterations were done on steering armlengthandthe dimensions of tripod plate. The best suitable result wasthen selected considering maximum Ackermann percentage. Fig-2: Iteration for finding percentage Ackerman Fig -3: Tripod dimension Steering geometry Ackermann Geometry Steering mechanism Tripod mechanism Ackermann angle 22.52° Steering arm length 90 Tie rod length 424.63 mm Inner wheel lock angle 40.89 Outer wheel lock angle 23.16 Percent Ackermann 70.14° Table-1: Design Values from iteration From above iteration, Percentage Ackerman = (1170.60- 334.14)/1170.60 *100 = 70.14% 2.4. Calculations Parameters Values Wheel Base 44” Front Track Width (l) 42” Track (b) 926.8 mm Tyre width (w) 127 mm Front axle load 90 kg Load on each tire 45 kg Scrub radius (e) 26.12 mm Kingpin Offset 70 mm Steering arm length 90 mm Turning radius of C.G of vehicle(considered for calculation purpose)R 3 m Turning radius of inner wheel Ri 3 - 0.5334 = 2.4656 Turning radius of outer wheel Ro 3 + 0.5334 = 3.5334 Coefficient of friction for dry road 0.7 Length of steering handle 700 mm Turning velocity of vehicle 4.53 m/s Height of C.G. of vehicle 17.35” Mechanical trail 46.54 mm Table-2: Input parameters 2.4.1. Static Calculations: Ackermann angle = tan-1(b/2l) = tan-1 (926.8/2*44*25.4) = 22.52 Radius of gyration (k) = w2/8 = 1272/8 = 2016.125 mm Effective torque arm length (h) = sq. root (k+e2) = (2016.125+26.122) = 51.94mm Moment at kingpin = g*W*h*µ = 9.81*45*51.94*0.7 = 16050.239 N-mm Force at tie rod ends = moment at kingpin/ steering arm Length = 16050.239 /90 =178.335 N Force at Tripod = 178.335 /0.9
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  International Research Journalof Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 04 Issue: 12 | Dec-2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 6.171 | ISO 9001:2008 Certified Journal | Page 1464 =198.151 N Moment at tripod = Force at tri pod*Arm of tri pod =198.151*73 =14465.03 N-mm Moment at tripod = moment at steering handle 14465.03= Steering effort / handle length Steering effort =14465.03/700 Steering effort = 20.664 N 2.4.2. Dynamic Calculations: Consider vehicle taking left turn, Cornering ‘g’ force = v2/Rg = 4.532/3*9.81 =0.697 N Weight transferred on right tire during cornering = ( g- force*height of C.G.* front axle load)/track width = 0.697*13.27*90/42 = 19.819 kg Weight on right tire (Wr) = W + weight transferred during cornering =45+19.819 =64.81 kg Weight on left tire (Wl) = W - weight transferred during cornering =45-19.819 =25.181 kg Lateral force on left tire = Wl*v2/Ri =25.181 *4.532/2.4656 =209.578 N Lateral force on right tire = Wr*v2/Ro =64.81 *4.532/3.5334 =376.39 N Total lateral force = lateral force on left tire + lateral forceon right tire = 209.578 +376.39 = 585.97 N Moment at kingpin = total lateral force*mechanical trail = 585.97 *46.54 = 27271.255 N-mm Self aligning torque = lateral force*contact patch/6 = 585.97 *127/6 =12403.03 N-mm Total torque = moment at kingpin + self-aligning torque =27271.255+12403.03 = 39674.286 N-mm Force at tie rod = total torque/steering arm length = 39674.286/90 =440.825 N Force at inner tie rod end = 2*force on tie rod = 2*440.825 = 881.65 N Moment at steering shaft = force at inner tie rod end * tripod length = 881.65*73 =64360.509 N-mm Theoretical steering effort = Moment at steering shaft / (Steering handle length) =64360.509/700 =91.943 N-mm 3.0 ANALYSIS USING ANSYS The steering system is designed in CREO 3.0 and analysis is done in ANSYS for maximum deformation & maximums stresses. Fig-4: Maximum Deformation Fig-5: Maximum Stress (Von-Mises theory) Sr. No Parameter Values obtained 1 Maximum deformation 0.0095mm 2 Maximum stress 14.93Mpa Table-3: Results of analysis
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  International Research Journalof Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 04 Issue: 12 | Dec-2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 6.171 | ISO 9001:2008 Certified Journal | Page 1465 4. IMPLEMENTATION OF TRIPOD MECHANISM The designed steering system is manufactured and assembled in quad bike as shown in figure below & Quad- Bike is tested in various off-road conditions. Fig-6: Assembly of Tripod steering Fig-7: Quad bike 5. CONCLUSION Tripod steering was installed on a quad bike and was tested on the various rough terrains. The results were better stability and minimum steering effort. Althoughithas limitation of having comparatively less Ackermann percentage, its best suited for the quad bikesdue to steering ratio. The Ackermann percentage obtained was 70.14%and steering effort was 20.664N in static loading. REFERENCES [1] William F. Milliken and Douglas L. Milliken, “Race Car Vehicle Dynamics”; ISBN 1-56091-526-9. [2] Carroll Smith, “Tune to Win”. [3] V B Bhandari, “Design Of Machine Elements”.