Design & Fabrication of Reverse Gear Box Design & Fabrication of Reverse Gear Box for Go-Kart & For Handicapped Vehicle Ahmed Ansari 1, Ravi Shanker Kumar 2, Purnend Shukla 3, Jayesh Bane 4, Wasim Khan 5 1,2,3,4,5 Automobile Engineering, Theem College of Engineering Abstract The project is specifically designed and fabricated for the convenience for taking go-kart vehicle in reverse direction during the event of racing. As the racing track of the go-kart is not in a straight line, it has some sharp turn, at that to pull the vehicle on the racing rack or have to take marshal. In above process the time consuming is more, as in racing time is more important parameter, we have implemented the reverse gear box, using this driver just have to pull the shifter lever and the forward drive is converted into reverse drive. Which help the driver to come on the racing track using engine power. We can also implement it in the handicapped person vehicle. As the mobility of physically disabled person is a concerning social issue nowadays. In case of the handicapped people, who drive two wheelers with extra support wheels face much problem to take the vehicle out of the parking by pushing the vehicle with legs. In order to take the vehicle out of the parking, they need to seek others help or they should push it out of the parking. As a help to them, this research paper aims at designing and fabrication a reverse gear mechanism, which will be fitting to the vehicle with little modifications of the existing mechanism. Keywords Gearbox, Reverse gearbox, Go-kart, Handicapped vehicle, Gears. I. INTRODUCTION Gearbox is enclosed system of assembled gears that transmits mechanical energy from a prime mover to an output device. A gearbox can also change the speed, direction, or torque of mechanical energy. Gearbox is a device placed between the clutch and propeller shaft. It allows the engine to run at different speeds relative to road vehicles, so as to maintain its power and regulates the torque. The vehicle requires high torque when climbing hills and when starting, even though they are performed at low speeds. On the other hand, when the vehicles are running at high speeds on the road level, high torque is not required because of momentum. Reverse gearbox, as the name suggest will give the reverse direction movement to vehicle. Reverse gearbox in this project is designed especially for gokart and handicapped person vehicle. Gear is a machine that can change the speed of the vehicle. It has a part having cut teeth, or cogs, that mesh with another toothed part in order to transmit torque. The rotating teeth are the cause of the changing energy from mechanical energy to kinetic energy. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine. Geared devices can change the speed, magnitude, and direction of a power source. The almost common situation is for a gear to mesh with another gear. However a gear can also mesh a non-rotating toothed part, called a rack, thereby producing translation instead of rotation. Continuous variable transmission is a system that makes it possible to vary progressively the transmission ratio. Therefore, it allows selection of an infinite number of transmission ratios between driving and driven shaft. Continuous variable transmission is also an automatic transmission system, which changes the diameter of input shaft and output shaft directly instead of going through several gears to perform gear ratio change. The use of continuous variable transmission can provide gear DOI : 10.23883/IJRTER.2017.3101.HPGXM 401
transmission ratio between two designed values with infinite number of steps. Certain designs can also provide zero and negative values for transmission ratios. Therefore, there is no need for clutch for disengagement and reverse gear for backward movement of vehicle. Such designs are called Infinite Variable transmission (IVT) and are able to provide full speed in reverse also. The time line progress in Continuous variable transmission technology is given below. Year Progress in CVT Innovation 1490 Leanardo da Vinci sketches a stepless CVT 1886 First toroidal CVT patent field 1935 Adiel Dodge receives U.S. patent for toroidal CVT 1939 Fully automatic transmission based on planetary gear system introduced 1958 Daf (of The Netherlands) produces a CVT in a car 1989 Subaru Justy GL is the first U.S.-sold production automobile to offer a CVT 2002 Saturn Vue with c CVT debuts, first Saturn to offer CVT technology 2004 Ford begins offering a CVT II. COMPONENTS AND MATERIAL SELECTION The components needed for the design of reverse gearbox are input shaft and output shaft, idle shaft, gears, selector, bearings, circlips, casing plates. Gears are arranged in constant mesh type in particular manner. The schematic/actual diagrams are shown below.. Software model (Solid works model) of Gears Actual view of Ball Bearing @IJRTER-2017, All Rights Reserved 402
Front and Isometric view of splined Input shaft Front and isometric view of idler shaft Front and isometric view of Output Shaft The material, dimension and quantities of these components are tabulated below: Components Materials Dimensions (in mm) Designations Quantities Input Shaft Carbon steel 40C8 L 175-1 Output Shaft Carbon steel 40C8 L 140-1 Idle Shaft Carbon Steel 40C8 L 110-1 Gear SAE 1045 (H.T) OD 47-2 Gear SAE 1045 (H.T) OD 55-1 Gear SAE 1045 (H.T) OD 50-1 Gear SAE 1045 (H.T) OD 35.5-1 Ball Bearing SAE 52100 15 35 11 6202 3 Ball Bearing SAE 52100 17 35 10 6003 2 Ball Bearing SAE 52100 20 37 9 16404 1 Selector Aluminium - 1 Circlip High Carbon Steel EN-42J ID 15-4 @IJRTER-2017, All Rights Reserved 403
Circlip High Carbon Steel EN-42J ID 17-1 Circlip High Carbon Steel EN-42J ID 20-5 Casing plate Aluminium 170 120 150-6 III. MATHEMATICAL MODELLING OF GEAR RATIO A. Calculations of Pitch Diameter and Module of different gears: Gear 1: Outside diameter of Gear 1 (OD) = 47 mm Number of teeth on Gear 1 (N) = 24 Pitch = (OD N) / N+2 = 47 24 / 24 + 2 = 43.38 mm Module = Pitch Dia / No. Of teeth = 43.38 / 24 = 1.8 Gear 5: Outside diameter of Gear 5 (OD) = 35.5 mm Number of teeth on Gear 5 (N) = 21 Pitch = (OD N) / N+2 = 35.5 21 / 21 + 2 = 37.89 mm Module = Pitch Dia / No. Of teeth = 37.89 / 21 = 1.8 Gear 4: Outside diameter of Gear 4 (OD) = 47 mm Number of teeth on Gear 4 (N) = 24 Pitch = (OD N) / N+2 = 47 24 / 24 + 2 = 43.384 mm Module = Pitch Dia / No. Of teeth = 43.384 / 24 = 1.8 Gear 2: Outside diameter of Gear 2 (OD) = 55 mm Number of teeth on Gear 2 (N) = 29 Pitch = (OD N) / N+2 = 55 29 / 29 + 2 = 51.45 mm Module = Pitch Dia / No. Of teeth = 51.45 / 29 = 1.77 Gear 3: Outside diameter of Gear 3 (OD) = 50 mm Number of teeth on Gear 3 (N) = 26 Pitch = (OD N) / N+2 = (50 26) / 26 + 2 = 46.428 mm Module = Pitch Dia / No. Of teeth = 46.428/26 = 1.77 B. Engine Specifications: Maximum Power output from engine = 5.83 kw @ 7500 rpm Maximum Torque = 8.83 Nm @ 5500 rpm Taking maximum torque, T = Ft Normal force, (Taking pressure angle, ) Resultant force, @IJRTER-2017, All Rights Reserved 404
Pitch line velocity: Face width and Gear: From Eqn no (1), b (Eqn. no. 1) Dimetral pitch = = 14.11 cm = 0.562 inch b (Eqn. no. 1) b b b We have taken, b = 10 mm inch cm Tooth thickness at pitch diameter, For Gear 1, 4 and 5: Tooth thickness, t = For Gear 2 and 3: t = t = 2.82 mm Tooth thickness, t = t = t = 2.78 mm Lewis equation for both bending stress: By similar triangle, Eqn (1) From Eqn (1) and Eqn (2), 4x Eqn (2) Eqn (3) @IJRTER-2017, All Rights Reserved 405
Where y is defined as Lewis form factor From Eqn (3) and Eqn (4), The above equation is in term of circular pitch Eqn (4) Eqn (5) Let, which is known as modified Lewis form factor Now from the table of Lewis factor, Eqn (6) Eqn (7) CAD model (Software model) of assembly of gears in Reverse gearbox @IJRTER-2017, All Rights Reserved 406
Actual view of gear assembly reverse gear box IV. FABRICATION A. Gear ratio calculation: Gear ratio cab be calculated by the following formula Gear ratio = No. of teeth in driver gear / No. of teeth in driven gear B. Forward direction: Impact gear (G1) is meshed with one idler gear (G5) and then idler gear is meshed with the output gear (G4). Input gear G1 has 24 teeth. Output gear G4 has 24 teeth. And the idler gear G5 has 21 teeth. The gear ratio for G1 and G5 is: Gear ratio = 24/21 = 1.142 = 1 The gear ratio for G5 and G4 is Gear ratio = 21/24 = 0.875 = 1 Therefore overall gear ratio = 1.14 0.875 = 0.999 = 1 For every one revolution of the input gear, the output also turns over revolution. C. Reverse Direction: For reverse directions Input gear is G2, Output gear is G3. For reverse direction input gear is literally meshed with output gear G3. Input gear G2 has 29 teeth. Output gear G3 has 26 teeth. The gear ratio for input and output gears The gear ratio = driver/driven = 29/26 = 1.11 = 1.11:1 For every 1 revolution of a input gear the output gear turn 1:1 revolution @IJRTER-2017, All Rights Reserved 407
V. CONCLUSION Reverse gearbox is designed for the mobility of an automobile or motor vehicle in backward direction. The proper design of gears should be there. Material selected should be such that it can overcome all type of stresses which in active condition. Casing of the gearbox must avoid all leakages of oil during performance. REFERENCES 1. P. J. L. FERNANDES, Tooth bending fatigue failures in gears, (IRJET Vol.02 Issue:March 1996) 2. R.Dhanasekaran, Crack Failure of Planetary Gearbox Sun Gear (International J. of Recent Trends in Engineering and Technology, Vol. 3, No. 6, May 2010) 3. Ravmond,J. Drago, The effect of material defects on gear performance A case study, (American Gear ManulllctufulS Association, 7500KIng,Street Suite201, May 1994) 4. Hemanshu D. Joshi, Mode and cause of failure of a Bevel gear-a review (International Journal of Advance Engineering and Research Development (IJAERD) Volume 1 Issue 2, March 2014,) 5. Arvind Yadav, Different types Failure in gears-a Review (International Journal of Science, Engineering and Technology Research (IJSETR) Volume 1, Issue 5 November, 2012) 6. V.S.Panwar, A CASE STUDY ON VARIOUS DEFECTS FOUND IN A GEAR SYSTEM (International Research Journal of Engineering and Technology (IRJET) Volume: 02 Issue: 03 June, 2015) 7. N.Venkatesh, Reverse Gear Mechanism in Two Wheeler for Physically Challenged People (International Journal of Scientific & Engineering Research, Volume 7, Issue 05 May, 2016) 8. Elizabeth L. Krause, Forward vs. Reverse Gear: The Politics of Proliferation and Resistance in the Italian Fascist State (,January 1927) @IJRTER-2017, All Rights Reserved 408