Makoto Hoki

Tractors and their power units.

1 Development of the Tractor.- Tractor Types.- Some World Variations in Tractors.- Functions of a Farm Tractor.- Sources of Energy.- Energy Conversion Devices.- The Future Engine.- Trends in Tractor Design.- 2 Thermodynamic Principles of Internal-Combustion Engines.- Specific Heat.- Entropy.- Energy Changes.- Constant-Volume Changes.- Constant-Pressure Changes.- Isothermal Changes.- Adiabatic or Constant-Entropy Changes.- General or Polytropic Changes.- Changes in an Adiabatic Expansion of a Perfect Gas.- Determination of the Value of n from an Actual Compression Line.- Equations for Nonflow Processes.- 3 Internal-Combustion Engine Cycles.- Simplifying Assumptions.- The Ideal Air-Standard Otto Cycle.- The Ideal Air-Standard Diesel Cycle.- Actual Cycles and Causes for Deviation from the Ideal.- 4 Fuels and Combustion.- Sources of Fuels.- Chemical Composition of Petroleum.- Petroleum Refining.- Combustion.- Gasoline Tests and Their Significance.- Antiknock Quality.- Factors Affecting the Octane Number Requirement.- Volatility.- Distillation.- Reid Vapor Pressure Test.- Sulfur Content.- Corrosion Test.- Gum Content.- Gravity.- Heating Values.- Gasoline Additives.- Diesel Fuel Tests and Their Significance.- Cetane Number.- Heating Value of Diesel Fuel.- Viscosity.- Carbon Residue.- Flash Point.- Pour Point and Cloud Point.- Ash Content.- Diesel Fuel Additives.- Alternate Fuels.- 5 Engine Design.- Engine Design-General.- Stroke-to-Bore Ratio.- Crankshafts and Firing Orders.- Tractor Engine.- Valve Design.- Valve Materials, Design, and Application.- Valve Timing.- Valve Clearance Adjustment.- Valve Seats.- Valve-Opening Area.- Cams.- Combustion Chamber Design.- Effect of Compression Ratio.- Piston Crank Kinematics.- Inertia Force of Connecting Rod.- Inertia Force of Single-Cylinder Engines.- Crank Effort.- Flywheels.- Balance of Single-Cylinder Engines.- Balance of Multicylinder Engines.- Principles of CI Engine Operation.- Construction of Diesel Engines.- Combustion Chamber Design.- Fuel-Injection Systems.- Fuel Injectors.- Turbochargers.- Matching of Turbocharger to Engine.- Aftercooling.- Engine Noise.- 6 Electrical Systems.- Battery.- Starting Motor.- Electrical Charging.- Battery Ignition System with Breaker Points.- Magneto Ignition System.- Ignition Timing.- Spark Plugs.- Sensors.- Environmental Problems.- 7 Engine Accessories.- Speed Control.- Principles of Centrifugal Governor Action.- Spark Arresters.- Mufflers.- Air Cleaners.- Air Inlet Location.- Precleaners.- Dry-Type Air Cleaner.- Dust Composition.- Air Cleaner Tests.- Engine Cooling Systems.- Cooling Load.- Heat Transfer.- Air Cooling.- Radiator Design.- Radiator Construction.- Temperature Control.- Antifreeze Materials and Coolants.- Corrosion and Radiator Deposits.- Pressure Cooling.- Quantity of Air.- Fans.- Engine Cooling Summary.- 8 Lubrication.- Types of Lubricants.- Properties of Lubricants.- Viscosity.- Classification of Oil by Viscosity.- Classification by Service.- Universal Tractor Oils.- Oil Additives.- Journal Bearing Design.- Oil Contamination.- Oil Filters.- Lubricating Oil Systems.- 9 Human Factors in Tractor Design.- Operator Exposure to Environmental Factors.- Operator Exposure to Noise.- Operator Exposure to Vibration.- The Operator-Machine Interface.- Noise and Vibration Control.- Operator Seating.- Sound Control in Operator Enclosures.- Spatial, Visual, and Control Requirements of the Operator.- Rollover Protection for Wheeled Agricultural Tractors.- Thermal Comfort in Operator Enclosures.- Safety.- 10 Traction.- Traction Mechanics.- Mohr-Coulomb Failure Criteria.- Traction Performance Equations.- Traction Prediction from Dimensional Analysis.- Performance of Four-Wheel, Tandem, and Dual Tires.- Tire Size, Load, and Air Pressure Relationship.- Radial-Ply Construction.- Tread Design.- Effect of Lug Spacing.- Traction Improvement.- Tracks.- Tire Testing.- Traction Devices for Paddy Fields.- 11 Mechanics of the Tractor Chassis.- Simplifying Assumptions.- Equations of Motion.- Static Equilibrium Analysis-Force Analysis.- Static Equilibrium Analysis-Maximum Achievable Drawbar Pull.- Static Equilibrium Analysis-Four-Wheel-Drive.- Longitudinal Stability.- The Tractor as a 2-Degree-of-Freedom Vibratory System.- Transient and Steady-State Handling.- Lateral Stability in a Steady-State Turn.- Three-Dimensional Static Analysis.- Center of Gravity Determination.- Moment of Inertia Determination.- 12 Hydraulic Systems and Controls.- Hydraulic Component Symbols.- Hydraulic Components.- Motor Performance.- Accumulators.- Valves.- Hydraulic Fluids.- Classification of Hydraulic Controls.- Draft Sensing.- Automatic Control.- Complete Hydraulic System.- Power Steering.- Noise in Hydraulic Systems.- Hitches.- Tractor Kinetic Energy.- Integral Hitch Systems.- Three-Point Hitches.- Quick-Attaching Coupler for Three-Point Hitches.- 13 Transmissions and Drive Trains.- Complete Drive Train.- Transmission Types.- Friction Brakes and Clutches.- Spur and Helical Gears.- Bevel Gears.- Gear Design.- Planetary Gear Systems.- Differentials.- Transmission Drive Shafts.- Antifriction Bearings.- Drive Train Speeds and Loads.- Electronic Transmission Controls.- Torsional Vibration.- Computer Simulation.- 14 Tractor Tests and Performance.- Tractor Performance Criteria.- Power Measurement Methods.- Absorption Dynamometers.- Electric Direct Current Dynamometers.- Shop-Type Dynamometers.- Drawbar Dynamometers.- Torsion Dynamometers.- Chassis Dynamometer.- Power Estimating-Field Method.- Air-Supply Measurement.- Engine Pressure Indicators.- Fuel Flow Meter.- The Nebraska Tractor Tests.- Globalization of the Tractor Industry.- Correction for Atmospheric Conditions.- Torque Curves.- Engine Performance.- Efficiency of Tractor Engines.- Actual Power Output and Fuel Consumption.- Tractor Reliability.- Appendixes.- A Standards for Agricultural Tractors.- B Standard Graphical Symbols.- C Agricultural Tractor Tire Loadings, Torque Factors, and Inflation Pressures-SAE J709d.- D Conversion Factors.

Fuels and combustion

Almost all of the fuels commonly used in farm tractors are products of crude petroleum. As fossil fuels become scarce, other fuels will have to be used. There are many factors that must be considered in the selection of an alternate fuel. Some of these factors are cost per unit of work done, availability, compatibility with the engine, safety, storage, management, and convenience. A section at the end of this chapter describes the properties of some of the alternate fuels most likely to be used in the future.

Why does soil not stick to enamel coating

Abstract Recently, a number of investigations into the use of enamel coating for agricultural applications have been carried out. These investigations have revealed that an enamel coating reduces friction, adhesion and draft requirements of agricultural equipment in the soil. It is not known which characteristics of the enamel coating help in the improved performance. Therefore, this study was conducted to look into some physical, chemical and mechanical properties of enamel coating. The investigation included measurement of surface roughness, soil-metal adhesion and friction, hardness, and electrical conductivity, as well as electron scanning microscopy. The properties of the enamel coating studied were compared with the properties of a mild steel surface. These investigations revealed that an enamel coating does possess some special characteristics, different from the mild steel surface, which improve its performance in agricultural applications.

Human Factors in Tractor Design

The design of the modern tractor includes considerations of human factors. These factors, when properly incorporated in design, allow the operator to perform many complex tasks with efficiency, safety, and a minimum of fatigue. In general, human factors include such items as riding comfort, visibility, location and arrangement of controls, ease of operating controls, design for thermal comfort, and sound control. A typical work-space control center for a modern tractor is shown in figure 9–1.

Field testing of a PTO powered disk tiller

Abstract Field testing of a PTO powered disk tiller was conducted in Bangkok clay soil. Tests were conducted at different forward speeds of 1,2,3,4 and 5 km/h and 33, 28 and 23° gang angles. Average PTO speed was 540 rpm and average soil moisture content was 26% during all the tests. The draft requirement was measured by a three point linkage dynamometer. The PTO torque was measured by a slip ring torque transducer. Specific draft, specific torque, power and energy consumption to till a unit volume of soil were calculated for different gang angle settings during passes 1 and 2. Quality of work was assessed in terms of soil cone index. Better tillage performance was observed at 28° gang angle than at 33°. At 23° gang angle the implement did not penetrate well due to the gage wheel remaining on unplowed soil. It was observed that at 28° gang angle setting, the implement consumed less power compared to the 33° gang angle setting at all forward speeds and passes. It consumed as much as 27% more power at 33° gang angle setting than at 28° gang angle setting. The power consumption decreased with higher passes. The energy consumption was higher at 33° gang angle than at 28°. It was also higher at lower forward speed compared to higher forward speed at any given gang angle setting and pass. The work quality in terms of soil cone index at 28° gang angle was better than at 33° gang angle. Disk tiller performance in unpowered mode was also evaluated. It consumed more draft power during unpowered mode compared to powered mode.

Tractor Tests and Performance

The performance of farm tractors can be expressed in many ways. The criterion that best describes the performance depends largely upon the intended use of the tractor.

Mechanics of the Tractor Chassis

An understanding of the statics and dynamics of farm tractors is important in the analysis of tractor performance, stability, ride, and handling. This chapter provides an introduction to these individual areas while attempting to emphasize their interrelationships.

Hydraulic Systems and Controls

This chapter discusses hydraulic systems, their control systems, and some of the principles of tractor hitches.

Transmissions and Drive Trains

The tractor drive train has three functions. It transmits power from the engine to the wheels, pto, hydraulic pump, and other auxiliary drives; changes the torque and speed into the torque and speed required by the particular drive; and provides means for operator control with disconnect clutches and speed ratio selection for the wheel and pto drives. The power transmitted by the drive train is approximately constant, changing only by the amount of the small gear and bearing friction and windage losses that occur.

Development of the Tractor

Mechanization of agriculture has several objectives: 1. To increase the productivity per agricultural worker 2. To change the character of farm work, making it less arduous and more attractive 3. To improve the quality of field operations, providing better soil environment for seed germination and plant growth