Design and Fabrication of Power Scooter

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December, 2013

Vol 2 Issue 13

ISSN 2278 – 0211 (Online)

Design and Fabrication of Power Scooter Shailesh S. Pachbhai Student, M. Tech (CAD/CAM), Department of Mechanical Engineering G. H. Raisoni College of Engineering, Nagpur, India Laukik P. Raut Assistant Professor, Department of Mechanical Engineering G. H. Raisoni College of Engineering, Nagpur, India Abstract: The concept of model taken from children’s scooter bicycle. The complete body looks like a scooter bicycle in which platform is provided for standing and driving the power scooter. This product is a small power S.I. engine, used for various purposes, equipped with powerful single cylinder, 2 strokes, air cooled engine, utilizing centrifugal friction clutch. It is economical in petrol consumption; scooter can be driven comfortably with the help of streamline design of the body and also provided with front hydraulic shock absorber. It has compact structure and aesthetic shape. Some modification and improvement done in the engine to increase its power and efficiency. At the end, the model is tested by several people and their comments are recorded and performed some efficiency tests. Key words: Power scooter, 2 stroke, engine, efficiency 1. Introduction Scooters are a subclass of motorcycles and are very popular as transportation in urban and rural areas. Some types of scooters that we will find zooming up and down the highways and city streets. The user can tread the pedal of the tread board successively to move the scooter forward. Generally, there are several types of scooter operation. High power scooter usually uses a small engine with gasoline. 1.1. Idea Behind Development A power scooter is an engine-operated one-person capacity vehicle for low mobility. It is specially designed for those who having difficulty in moving or walking frequently from one place to another. A power scooter is different from a wheelchair which is motorized, and is generally used for indoor use and usually costs a great deal more. 1.2. Concept Design Power scooters have 2 wheels powered by a 49.8 cc petrol engine which is fixed at the rear end of the scooter. A power scooter is rear wheel drive get the power from the engine by a pulley and belt drive. This scooter provides all the controls for driving it by the driver. It is provided with simple platform for standing and drives it comfortably. Some people think that power scooter is difficult to operate, so they are less worried about to purchase it. Once a person gets the feel for it, the control console makes it simple. Power scooters are also equipped with advanced brake systems, so stopping is simple, safe and comfortable. Now days, small scooter becomes popular especially during recreation time, relaxing and for human exercise. Most of the power scooters are operated by engine or just using our leg to move scooter like playing skate board. The problem in most of the scooter is that they are not flexible though it is very small. 1.3. Type Of Scooter Different types of scooters are as follows:  Gas Scooter The speed of these scooters can be stepped up to levels that cannot be achieved in case of other types of scooters. These scooters are also available in different sizes and weights depending on the gas tank.

INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH & DEVELOPMENT

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Electric Scooters An electric scooter is a battery-operated one-person capacity vehicle. Usually, it uses DC electric motor for its operation. It may have three wheels or four and also does not create pollution. Mobility Scooter This is a modified version of the electric scooter and is made for special people like the disabled and the aged people. These scooters are extremely stable, as they have more than two wheels. Some even have four wheels. Foldable Scooter This kind of scooter made to be small space storage and easy to bring from one place to another place. Either use electric source or kick power moving. Utility Scooter The utility scooters are extremely handy and are used for a wide range of purposes. This variety serves multiple purposes. Retro Scooter Based on modification from classic scooter like Vespa. It refers to how much a design adheres to the original Vespa. Chopper Scooter Many scooters available come in bodywork that rests on a tubular frame. Because of this, it is relatively easy to modify and give the appearance of small Harley chopper motorcycles. Because of their appearance, it is called chopper scooters.

2. Literature Survey Yefei Li[1] presents methodology on structure design based on human factors, he build a three dimensional parametric model of a scooter for ergonomic analysis. He build a three dimensional digital model of scooter in Pro/Engineer. The modeling and size specification of scooters for different children was given as example to show the whole design process. The development of human factors, computer aided design and anthropometry improves designers and manufacturers provide customer more and more suitable products to satisfy their needs. The actual model shown in Figure.1

Figure 1: Three Dimensional Assembly Model of Scooter Top View, Lateral View and Front View [1] Huijuan[2] discussed the design of transmission and provided a method to modify a CVT to 4- speed manual transmission. The principle design of transmission system is found in the manufacture and experiment of the racing car. According to the design of transmission, the actual manufacture assembly is made. The result of the real vehicle test shows that the fuel economy of the transformed system is better than the original CVT system in theory and actual Performance. At the same time, the extensive use of


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the Computer-aided design in the design greatly reduces unnecessary steps in the actual manufacture process, which makes the real vehicle manufacture and assembly accurate and smooth. The final assembly shown in Figure.2

Figure 2: Final Assembly [2] Fucai HU [3] developed a 3D finite element model of the band brake on anchor windlass is established by using PRO/E software. Temperature distributions of the brake band and the friction linings are analyzed with a finite element analysis software-MSC. Marc. He found that the highest temperature does not appear in the end, but at a certain moment before the end. For brake band, temperature rises slowly at the beginning and rises quickly later. The simplified 3D finite element model is shown in Figure.3.

Figure.3 Finite Element Analysis Model [3] Jianye Guo [4] introduces requirements, structures, working principle and design of the V-belt pulley absorber in the automobile engine. To generate the torsional vibration frequency response characteristics curve of the crankshaft in automobile engine, the formula has been deduced and antivibration effect have been explained by the example that are caused by the physical parameters (including rotor inertia, damping, and torsional rigidity) of rubber ring, outer ring and wheel hub, these three components constituting with the triangle groove, a belt pulley absorber.

Figure 4: The Structure of Belt Pulley Absorber [4] 1. Wheel Hub; 2.Rubber Ring; 3. Outer Ring


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Rohan Dwivedi [5] explained the idea of adaptive suspension system, he designed the actuating suspension system for neutral jerks which are caused by speed breakers and uneven surfaces on the roads. The system designed is reconfigurable and real time. The system should be able to control engine and the braking systems is the main aim of this project. Various kinds of sensors like LASER detector, ultrasonic sensor, force sensor, accelerometer and tachometer will play main part in the Adaptive Suspension System. For controlling the suspensions and one ECU will be involved in actuating the braking and engine system, different electronic control units are also be used. The whole system can be highly useful against jerks and mountainous road where there are more possibilities of bad road conditions. The wear and tear of vehicles other parts also gets reduced due the less exertion of chassis of the vehicle. The sensors present in the vehicle also check the speed of the vehicle which reduces the risk of any accident due to bad road conditions .The system structure is shown in Figure.5

Figure 5: System Structure of Adaptive Suspension System [5] Based on the functional decomposition strategy, He Bin[6] presents a systematic approach to automated conceptual design of multiple input and multiple output mechanical transmission system. He also proposed transmission functional representations, and the integration of motional function matrix with mechanical transmission knowledge base. After the method of single input and single output system is proposed, multiple inputs and single output system, and single input and multiple output system are simplified into single input and single output system. Then by functional decomposition strategy, the multiple inputs and multiple output can be also solved. The mechanical transmission system of a robot is given as an example, which demonstrates that the methodology is obviously helpful for product innovation. This paper presents a new systematic methodology to increase opportunities for product innovation in automated MIMO mechanical transmission system conceptual design. As concerning problems of the current researches on mechanical transmission system conceptual design, a transmission functional model based on feature is built. The process of automated MIMO mechanical transmission functional is discussed in detail. 3. Design of Power Scooter A. PART SPECIFICATION 3.1. Engine The major types of engines are as follows: 3.1.1. Internal Combustion Engine In an internal combustion engine combustion takes place inside a cylinder. You need to mix fuel and air together. This mixing happens in the carburetor. The mixture of fuel and air goes through a valve into the cylinder. In the cylinder fuel and air get compressed by the piston. A spark plug makes a spark and ignites the air and fuel mixture. The explosion pushes the piston down. The piston pushes the connecting rod which turns the crankshaft. The crankshaft turns the flywheel. The spinning fly wheel is used to do some kind of work. The explosion in an internal combustion engine creates a lot of heat. It may be up to 1,200 degrees F. This heat can damage the engine. Internal combustion engines have a radiator. Water in the engine takes heat away from the engine and to the radiator. The radiator cools the water. 3.1.2. Diesel Engines Diesel engines don't use spark plugs to ignite the air and fuel mixture. The air in a diesel engine is compressed more than in a gasoline engine. The injector squirts fuel in the cylinder. When the fuel hits the hot air it ignites the fuel. The diesel engine doesn't need a carburetor or spark plug.


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3.1.3. Steam Engines Steam engines need fuel to make fire. The fire boils water which turns into steam. The steam goes through a valve and then pushes on a piston. The piston goes back and forth and turns the wheels. A connecting rod hooks the piston to a wheel.The main aim of choosing internal combustion engine is that in mobile equipment, internal combustion is advantageous since it can provide high power-toweight ratios together with excellent fuel energy density. Generally using fossil fuel (mainly petroleum), these engines have appeared in transport in almost all vehicles A 49.8 cc engine that delivers a maximum output of 1.67 HP @ 4500 + 500 rpm and torque of maximum 2.9 Nm TECHNICAL SPECIFICATION Bore 38.4 mm Stroke 43 mm Number of cylinders One horizontal Displacement

49.8 cc

Compression ratio

8.0:1 ( + 0.5)

[A]Maximum engine output [B] Maximum engine output Maximum torque

1.25 + 0.06 KW@ 4500 + 500 rpm

Air cleaner Weight of engine

Wire mesh 7.5Kg

1.67HP 2.943 @ 3000 rpm

Table 1: Technical Engine Specification

Figure 6: Engine Block 3.2. Carburettor Types of carburetor There are 3 basic types of carburetors in use today. They are the one barrel, two barrel, and four barrel. Typically, the type of engine and its use will dictate which carburetor is used. In high performance engines multiple carburetors may be used to deliver the amount of fuel required. No matter what type of carburetor your engine uses, National Carburetors is your source for high quality carburetors. The carburetor has several functions:  It combines gasoline and air creating a highly combustible mixture,  It regulates the ratio of air and fuel, and  It controls the engine's speed. When piston moves down the cylinder on intake stroke it draws air from the cylinder and intake manifold. A vacuum is created that draws air from the carburetor. The airflow through the carburetor causes fuel to be drawn from the carburetor through the intake manifold past the intake valves and into the cylinder. The amount of fuel mixed into the air to obtain the required air to fuel ratio is controlled by the venturi or choke. When air flows through the venturi its speed increases and the pressure drops. This causes the fuel


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to be sucked into the air stream from a hole or jet. When the engine is at idle or at rapid acceleration there is not enough air passing through the venturi to draw fuel. To overcome these problems other systems are used.

Figure 7: Carburettor of Power Scooter 3.3. Chassis Since the engine size and power is an essential design selection for the vehicle’s overall performance and we do not want to waste any materials by designing, the overall weight of the vehicle will be crucial. In order to reduce the overall weight of the scooter, objective will be accomplished by designing its steel chassis with advanced, lightweight. To build a light weight scooter chassis we will need to consider a number of different parameters, such as safety, static and dynamic stability, and structural integrity. Chassis of a power scooter, consisting of the frame (on which the body is mounted) with the wheels and machinery. The material used in this scooter is pipe with galvanized steel of 14 gauge and overall length of 40 inches. It has given a clearance of 5 inches from ground level.

Figure 8: Chasis 3.4. Brake Type The main types of brakes are disc brakes, band brakes, drum brakes, air brakes, and vacuum brakes. A brake is an apparatus used to slow or stop a moving vehicle, or, once the vehicle is stopped, to keep it from moving again. Most vehicles have wheel brakes, including automobiles, bicycles, motorcycles, and some airplanes. Wheel brakes are generally friction devices, using resistance and energy lost through heat to slow the vehicle. This is usually accomplished by pressing brake shoes either directly against the wheel or against a rotating piece of the brake attached to the wheel. In regenerative braking, the vehicle keeps this lost energy in the car’s system and reuses it later. The vacuum brake was originally devised for use on trains. These types of brakes works by creating air pressure changes in a compartment called the brake cylinder. Inside the cylinder is a piston, which is a mechanism designed to use the force of incoming air to move a rod. The rod is attached to the brake shoes. When the brake pedal is held down, air is let into the cylinder, which causes the piston to transfer that force onto the brake rod. The brake rod moves and, in turn, the brake shoes are pressed to the side of the wheel to cause friction. The concept behind the selection of band brake is that it is simple, compact, rugged, and can generate high force with a light input force. However, band brakes are prone to grabbing or chatter and loss of brake force when hot. These problems are inherent with the design and thus limit where band brakes are a good solution.


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Figure 9: Band Brake 3.5. Suspension Type Front axle telescopic type. The main advantages of the telescopic fork are that (i) it is simple in design and relatively cheap to manufacture and assemble; (ii) it is lighter than older designs using external components and linkage systems; For smooth out or damp shock impulse, and dissipate kinetic energy, a shock absorber is a mechanical device is designed.

Figure 10: Suspension 3.6. Transmission System A belt is a loop of flexible material used to mechanically connect two or more shafts which is rotated, often they are parallel. Belts may be used as a source of motion, to track relative movement, or to transmit power efficiently. Belts are wrapped over pulleys.

Figure 11: V-Belt Transmission System


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3.6.1. Design of Chassis In this power scooter, mild steel rod of outer diameter 38.0 mm and 8 mm inner diameter is used. It has gauge length of 62 mm & max load carrying capacity is 232 kg. and working load 140 kg. So for detailed analysis, factor of safety and strain energy stored in the body is necessarily to find out. Factor of safety = maximum load /working load = 2.254 KN/ 1.374 KN Factory of safety = 1.64 Volume of a rod is given by Where, d = diameter of rod (mm) r = radius of rod (mm) h = height of rod (mm)

441.786× 103 mm3 Backside idler that is commonly used to help increase the arc of contact on both pulleys. This idler forces a backward bend in the belt, which decreases belt life. The idler puts additional strain on the bottom portion of the belt, which may crack that section, for that purpose it is necessary to find out strain energy in the belt. Strain energy in belt is given by, Where, σ = stress V = volume E= Young's modulus

3.6.2. Design of V – belt V-belts are designed to operate in V-shaped grooves in the sheaves used for power transmission. V-belts have a major advantage over other types of belt friction drives; as the wedging effect of the belt pushing into the sheave results in lower belt take-up tension being required. For the same horsepower, sheave diameter, and sheave speeds, V-belts will operate with lower tension and, therefore, lower bearing load than other friction-type belt drives.

Figure 12: V-Belt Transmission


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Driver pulley

Driven pulley Diameter 60mm 80mm C.O.F 0.3 0.3 Speed 1000 r.p.m 1000r.p.m Power transfer max 1000 watt 1000 watt Angle of wrap 1 radian 1.5 radian Table 2: Dimensional Parameter of V-Belt

T1 – Tension in tight side T2 - Tension in slack side r1 – 30 mm radius in driver pulley Velocity is finding to determine deviations from the traditional calculations carried out with respect to tensions at different drives in a multiple pulley drive system of a conveyor. Velocity of belt is given by, Where, v = Velocity of belt d= diameter of belt N= speed V

The belt moves from the tight side to the slack side and vice-versa, there is some loss of power because the length of belt continuously extends on tight side and contracts on loose side. Thus, there is relative motion between the belt and pulley due to body slip. For this purpose power transmission is to be calculated. Power transmitted is given by,

---------- (I) We know that, 2.3 log (T1 / T2) = Lo (T1 / T2) = 0.13 = 1.348 ---------- (II) From (I) & (II)

As per standards density of rubber ρ = 1140kg/ m Mass of belt is given by, Mass Area × length × density

During rotation of belt drive, the belt is followed by a centrifugal force. The belt has mass and as it rotates along with the pulley it is subjected to centrifugal forces, no power is being transmitted and pulleys are rotating, the centrifugal force will tend to pull the belt.


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Centrifugal tension is given by, (Tc)

When belt drive is transmitting power the total tension on both sides will be given by,

Hence the total tension in the belt is found to be 170.52N which is less than the standard belt tension i.e. 200N. Therefore, It is found that the design of V- belt drive is safe. 3) Design of band brake Typically, the brake band is round; creating a loop that can be tightened or loosened around a shaft. The friction created when the belt is tightened helps to slow and eventually stop the rotation of that shaft. One of the major benefits of a band brake is the simplicity of the design. With fewer moving parts that other types of braking systems, a band brake assembly is easily maintained and can work properly for a number of years with no breakdowns.

Figure 13: Band Brake

Where, d- Diameter of drum N- Speed of shaft l- Band width Angle of contact

rad

We know that --------- (I)


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To find out braking torque, We can use

We also know that

------------ (II) From I & II

A means of lessening the amount of force needed to depress brakes used in vehicles .for this purpose power is calculated. Now taking movement about o

4. Fabrication and Assembly As per the design calculations, the various parts are selected and assembled together to get the final product.

Figure 14: Actual Model of Power Scooter 5. Modifications  Replacing 6v Ignition Coil By 12v By means of replacing 6V ignition coil by 12V, it helps in increase the intensity of spark in combustion chamber. CDI system provides much larger & hotter spark compared to magneto ignition system up to 40000v vs. maximum of 17000v from magneto. It also improves fuel efficiency.  Bore Diameter Bore diameter has been increased by 0.4mm which helped us to increase the power of engine.  Compression Ring Extra compression ring has added on piston in order to increase its compression ratio. Simultaneously, volumetric efficiency of engine also increases.  Reduction In Weight By using light weighted and optimum material results in reducing load ultimately the efficiency of engine increased.


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6. Working Power scooter works on the concept of Otto cycle in which suction, compression, expansion, exhaust strokes carried out and power is developed .It consist of piston, a cylinder block and ahead, which contains the valve train. The piston moves up and down in the cylinder block, driven by explosions of air fuel mixture that has been ignited by the spark. Valves open and close to allow the air fuel mixture to enter the combustion chamber. As the piston moves up and down, they turn a crankshaft which transforms the energy from piston into rotary motion. The rotational force of the crankshaft is transmitted to the rear wheel of power scooter. In this power scooter initially the person will start the scooter with the slight push and decompression lever in pressed position and the engine will start. As the engine starts the decompression lever is released. Once power is developed the pulley start rotating by using v-belt drive which transmit power from pulley to rear axle. Axle rotates the rear wheel and scooter start running. By using accelerator we increase or decrease the speed of power scooter. And to stop the scooter we have provided the band brake on the rear axle. To start and stop the engine a decompression lever is provided on the handle 7. Problem Faced During Design and Fabrication  AXLE At the time of first design of axle, when we apply the brakes the axle get unwound by braking force. Then at the next design, there was a minute ply between the split axle due to which the thread get weared. To overcome this problem, we have released tension and keep the cable relatively straight.  CDI UNIT [Capacitive Discharge Ignition] By means of some problem in starting coil and if some improper connection in the CDI unit, it gets fused. To overcome this problem of burned and worn points provided with a hotter spark because of the faster voltage rise and collapse time in the ignition coil.  BRAKE In the first stage, the disc braking system was selected. But it is very costly and not easily available in the market, so we think about its alternative and use band braking system.  REAR SUSPENSION Due to the compact space and engine mounting problems, we are not able to provide a rear suspension. So , telescopic shock absorber is used.  VIBRATION Vibration occurs in the scooter due to the jamming of centrifugal clutch bell and the belt of the transmission system not tight properly. We overcome this problem by properly tightening of V belt.  SILENCER When we design the silencer, the length is nearly equal to the length of scooter. So we provide the length of silencer as per space requirement 8. Troubleshooting 8.1. The Engine Does Not Start  Check the fuel tank.  Is the correct ratio of petrol plus lubricating oil in the fuel tank?  Make sure choke is in open position.  The fuel may be contaminated with water.  The spark plug may need cleaning or replacement.  The air filter may need cleaning.  The fuel filter may need cleaning.  The engine may be flooded with gasoline. Wait about 15 minutes and try again. 8.2. Engine Runs But Has No Power Or Acceleration  Check if the fuel mixture is within the correct ratio.  The gasoline may be contaminated with water.  The air filter may need cleaning.  The fuel filter may need cleaning.  Adjust fuel flow valve. 8.3. Engine Fails To Run Smoothly  Check if the choke is fully open.  Check if the fuel mixture is within the correct ratio.  The gasoline may be contaminated with water.  The air filter may need cleaning.


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The fuel filter may need cleaning. Adjust fuel flow valve.

8.4. Engine Can Run At High Speed, But Stops When Idling  Check if the choke is fully open, the spark plug may need cleaning or replacement.  Check if the fuel mixture is within the correct ratio.  Check for engine leaks. 8.5. Scooter Moves Forward Even At Idle  Engine speed is to set so fast.  Adjust fuel flow valve. 9. Result After performing some test we find out the following results: Emission test result performed out , it is observed that level of Carbon monoxide was 1.23ppm (Allowable range) and Hydro Carbon was 1445ppm (Allowable range). It is found that level of both was safe under the pollution standards. Engine performance carried out at different levels. It is observed for Load carrying capacity of 230 kg .Scooter’s gross weight is 42 kg and after performing test for milege, it is observed that the Fuel consumption is72 km/lit and has driven with a maximum speed of 40 to 45 km/hr. 10. Conclusion Due to the many problems of congestion, pollution and urban mobility, new modes of transportation, such as “Power scooter” personal transportation devices, increasingly seem to be an alternative to widespread automobile use. The Ergonomic evaluation also demonstrated that power scooter is easy to use in normal use situations, including situations involving obstacles, for a broad cross section of users. The devices also compare favorably with other types of vehicles, particularly in terms of stability, where they seem superior to other vehicles such as bicycles and mopeds. However, Power scooter is designed for a broader segment of the population and is meant to meet a wider variety of mobility requirements in urban communities. Power scooter would also generate transfers to alternative forms of mobility and use for short distances. The performance studies carried out in a closed environment also demonstrated that power scooter is easy to use in normal use situations as well as to get around obstacles. The survey results clearly show that a large majority of test participants found all scooter movements easy to perform. However, this device is targeted more for young people and seems primarily intended for recreational purposes. The evaluation results suggest that power scooter use is appropriate in closed environments, such as major industrial complexes, hospitals, shopping centers and airports. The reliability and safety of this device when used in urban communities; Social acceptance of power scooters help to reduce traffic problem. In future we can use flexible sitting arrangement also we can use advance braking and suspension system. This scooter can be modified according to once interest. Non-conventional fuel system can be adopted as the power source for this scooter. 11. References 1. Yefei Li1, Hui Jiang, Fangyu Li, Yonghui Xing” Research on structure design of scooter for children based on human factors,” IEEE978-1-4244-5268-2/09,2009 2. Huijuan He, Danlei Zhou, Shiqing Peng “Transmission System Design of FSAE Racing Car Based on Computer Technology” IEEE 978-0-7695-4522-6/11 DOI 10.1109/ICM.2011.339,2011. 3. Fucai HU, Beisi XIE, Hulin LI “Finite Element Analysis of Transient Temperature Field of Band Brake”, IEEE978-1-42449171-1/11, 2011 4. Jianye Guo, Lijie Zhao, Yanli Zhang, Jingkui Li, “Design of Belt Pulley Absorber in the Automobile Engine Based on the Dynamic Analysis,” IEEE 978-0-7695-4077-1/10 DOI 10.1109/ICICTA.2010.825,2010. 5. Rohan Dwivedi, Nitin Kandpal, Abhishek Shukla “Adaptive Suspension System”IEEE 978-1-4244-6928-4/10, 2010. 6. He Bin, Lv Hai Feng, Liu Wen Zhen, Han Li Zhi “Automated Conceptual Design of Multiple Input and Multiple Output Mechanical Transmission System, ” IEEE. 978-0-7695-3982-9/10 DOI10.1109/ICCEA.2010.172,2010


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