Tractor as Source of Mechanical Farm Power (2 hours)
History of development of tractors
Classification of tractors
Essential features of farm tractors
Ranges and availability in the country
Tractor selection criteria
Systems and Controls in Farm Tractors (20 hours)
Types of power transmission: two and four wheeled drive; hydrostatic and hydrodynamic drives; design principles for power transmission
Clutch system: purpose and types; principle of operation; functional requirements; design parameters and procedure
Gear box: purpose and types; principle of operation; functional requirements; design parameters and procedure
Differential and final drive: purpose and types; principle of operation; functional requirements
Steering system: purpose and types; principle of operation; components of mechanical steering; functional requirements; adjustments (camber, caster, toe-in, toe-out, kingpin inclination, tie-rod locking)
Brake system: purpose and types; principle of operation; functional requirements; design parameters and procedures
Hydraulic system: purpose and types; hydraulic circuit symbols; principle of operation; functional requirements; automatic position and draft controls
Auxiliary power transmission and power outlets: power take off (PTO) system, functions and types; belt, pulley and drawbar; special power drives for front and side mounted implements
Traction and Traction Theory (4 hours)
Mechanics of a rigid wheel (traction and towed)
Construction of tractor tyre
Inflation pressure
Theoretical soil thrust on traction device
Rolling resistance and travel reduction
Coefficient of traction and tractive efficiency
Tractive effort, rim pull, drawbar pull
Traction parameters and design of traction device
Traction aids and wheel ballasting: types and selection criteria
Soil compaction in tillage and traction
Mechanics of Tractor Chassis (4 hours)
Static and dynamic forces acting on tractor chassis
Location of center of gravity and moment of inertia
Static equilibrium analysis
Analysis for maximum achievable drawbar pull
Longitudinal stability and stability at turns
Tractor Hitching (3 hours)
Terminology used in tractor hitching
Types: single axis hitching, two-axes hitching, automatic hitching
Weight transfer and stability
Break-away principle and other safety devices
Power Tiller and Mini Tiller (4 hours)
Purpose and types
Range and availability
Control systems of power tillers
Ergonomic Principles in Tractor Design (3 hours)
Human factors in tractor design
Human tolerance to temperature, noise and vibration
Importance of ergonomic principle in tractor seat design, controls and control panel
Tractor Testing (3 hours)
Purpose of testing
Tractor test codes
Engine and drawbar performance at full and part load
Performance data of major makes and models of tractors used in Nepal
Economics of Tractor Use (2 hours)
Practicals
Tutorial (15 hours)
Clutch
Gear box
Brake system
Traction and traction theory
Mechanics of tractor chassis
Economics of tractor
Practical (30 hours)
Dissembling and assembling of clutch system, components involved and maintenance operation
Dissembling and assembling of gear box, components involved and maintenance operation
Dissembling and assembling of differential and final drive, components involved and maintenance operation
Study on steering system: components involved and adjustments of camber, caster, toe-in and toe-out
Dissembling and assembling of brake system, components involved and maintenance operation
Dissembling and assembling of hydraulic system, components involved and maintenance operation
Study on wheel parameters and ballasting in farm tractors
Hitching of mounted, semi-mounted and trailed type farm implements and stability analysis
Study on control systems of power tillers and mini tillers
