Agricultural Tractors Overview

Agricultural Tractor

• Agricultural tractor is a self-propelled, wheeled vehicle with two axles.
• It's designed for hauling trailers and agricultural machinery.
• Versatile machine for various agricultural tasks.
• It can perform both stationary and mobile jobs.
• It can pull or tow implements through traction or drawbar/PTO drive.

Definition of Tractor

• A self-propelled, wheeled vehicle with two axles, used to carry, pull, or propel agricultural implements and machines.
• Specifically designed to deliver high tractive effort/torque at slow speeds.
• A mobile power source for a wide variety of agricultural tasks.

Functions of Tractors

• Pulling implements behind.
• Pushing implements in front.
• Operating implements attached to it.
• Transmitting power to other machines using the PTO.
• Controlling and adjusting implements with hydraulic power.
• Driving implements with belt power.
• Transmitting power with flexible shaft.
• Providing power for highway transportation and handling.

Classification of Tractors

• Two-Wheel Drive: Power transmitted to rear wheels; small front wheels.
• Four-Wheel Drive: Power transmitted to all wheels.

Types of Steering

• Front wheel steering: Automotive-style control, ideal for row crops and fieldwork.
• Coordinated steering: Coordinates front and rear wheels for sharp turns.
• Crab steering: Counteracts implement drift on slopes, optimizing traction.
• Rear wheel steering: Maneuvers easily around obstacles and for specialized tasks.

Descriptions of Agricultural Tractors

• Compact Tractor: Four-wheel tractor with less than 20 hp. Used for landscaping, gardening.
• Farm Tractor: Four-wheel tractor with at least 20 brake horsepower. Used for heavy-duty agricultural tasks like plowing, seeding, planting.

Special Type Tractors

• Tract-type Tractor: Heavy-duty endless link device for heavy-duty operations (earth moving).
• All-Purpose or Row Crop Tractor: Designed to handle field and belt jobs (planting, inter-tillage).
• Orchard Tractor: Small-medium size for easy operation under trees.
• Industrial Tractor: Various sizes for industrial operations (heavy hauling, hoisting, excavating).

Parts of a Tractor

• The document lists numerous parts of a tractor, such as: canopy, ROPS, signal lights, driver's seat, rear wheel, implement, steering wheel, hood, headlight, ballast, front wheel, muffler, engine, foot throttle, clutch, auxiliary gear shift lever, and more.

Pre-Start Safety Check on a Tractor

• General Checks: Safety guards, loose parts, drawbar/three-point linkage, fluid leaks, tire treads.
• Specific Checks: Brake values, clutch pedal, oil level, cooling system, battery terminals.
• Air Cleaner: Clean (dry type), or replace and/or clean oil bath type.
• Lubrication: Grease fittings per manufacturer's timetable.

Tractor Safety

• Clutch safety: Won't engage starter unless clutch is depressed.
• Implement placement: Ensure implements are as low as possible to reduce overturn risks.
• Ballast/counterweight: Use to balance the tractor.
• PTO shield: Protect clothing and hair from getting entangled in the shaft.
• Roll-over protection structure (ROPS): Essential for safety in case of overturns. Be sure seatbelt is fastened.

Attach and Remove Trailed Implement

• Adjust draft bar and implement. Utilize a jack stand to support weight.
• Ensure tractor position aligns with implement hitch.
• Engage parking brake. Secure implement to drawbar.

Connect Remote Hydraulics

• Position tractor at a level site. Move components to lowered position.
• Disconnect hoses, stow away from dirt and water.
• Inspect connections for cleanliness, replacing caps as needed.
• Ensure hoses aren't kinked when stowed.

Attach and Remove a PTO Shaft

• Engage parking brake; disengage PTO drive. Put tractor in neutral or park
• Attach to implement (three-point link or trailed).
• Connect crossjoint and powershaft.
• Adjust implement for level position and safe operation.

Check the Coupling

• Ensure the power shaft coupling has the correct number of splines (grooves) for the RPM.
• Select appropriate power shaft (e.g. 540 rpm, 1000 rpm)

Check the Powershaft and Spring-Loaded Lock

• Check that the parts will fully extend without problems.
• Make sure sliding parts don't bottom out when compressed.
• Ensure both halves of the PTO shaft are properly locked together.

Three-Point Linkage Implement

• Describes the parts of the three-point linkage system for attaching implements to a tractor (e.g. lift arm, left/right draft links, top link).
• Also explains how to detach the implement.

Additional Readings

• Resources on agricultural tractor controls, specifications, and testing methods.

Tractor Brands & Makes

• List of common tractor brands and makes.

Tractor Terminologies

• Drawbar: Bar for hitching implements to the rear of the tractor.
• Drawbar power: Power output from the drawbar (sustainable over a distance).
• PTO shaft: Shaft providing rotational power to implements.
• PTO output power: Power measured at the PTO shaft.
• ROPS: Roll-over protective structure.
• Three-point linkage: Connects implement to the tractor.
• Ballast: Added weight to balance the tractor.
• Chassis: Tractor frame and supporting structure.
• Fast Hitch/Quick Hitch: System to quickly connect implements to the tractor 3-point hitch.

Tractor Power

• Power can be conveyed via drive wheels (pulling) or PTO shaft/belt pulley.
• Hydraulics can also power implements.

Power Performance

• Provides the relationships between various tractor power measures:
  • Drawbar, PTO, Transmission, Axle.

Power Train of a Wheel-Drive Tractor

• Diagram showing the flow of power from engine through various components to the wheels.

Functions of Power Transmission

• The transmission is critical for converting engine power. It facilitates changing torque and speed to match the implement's needs.

Clutch

• Device used to connect or disconnect the engine from the power train (or to engage/disengage the tractor drive). Enables shifting gears without shutting down the engine.

Differential

• Gear arrangement enabling one wheel to rotate faster or slower than the other (e.g., during turns).

Final Drive

• Gear reduction mechanism transmitting engine power from the differential to the axle and wheels. The output power has high torque and is at a low speed.

Power Take-Off Shaft (PTO)

• Shaft used for driving agricultural implements. Includes standard specifications for coupling and spline shaft diameters.

Drawbar Pull

• An important factor in tractor performance. Determined by wheel slip, engine power and factors like ground conditions, tractor weight, and implementation type.

Tractor Size Determination

• Tractor size depends on its capabilities (e.g., weight, horsepower). Tractor size determination is generally based on the amount of force an implement requires. Specific implementation resistance values are used in the calculation. This information is based on the soil type (dry/moist clay/silt loam).

Use of Specific Implement Resistance

• Tables outlining specific resistance values for various agricultural implements.

Classifications of Hitch System and Controls

• Discusses different hitch types (drawbar, semi-mounted, direct-mounted, direct-connected) for connecting implements to the tractor.