new developmentsin agricultural equipment tractors r. t. schuler national agrability project...
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NEW DEVELOPMENTSIN AGRICULTURAL EQUIPMENT TRACTORS
R. T. SchulerNational AgrAbility Project
University of Wisconsin - Madison
November 14 , 2006
Tractors
Guidance and Auto-Steer Global Positioning System Guidance Auto-Steer Autonomous
Transmissions Number of gears/speeds CVT - Continuously Variable
Transmission IVT - Infinitely Variable Transmission
Suspension Tractor Chassis Cab Seat
Global Position Systems
Basic GPSSatellite System Only (3 of 24)Low cost – automobilesError – 100 feet
Satellite Constellation
Global Position Systems
Basic GPSSatellite System Only (3 of 24)Low cost – automobilesError – 100 feet
Satellites plus free beaconIntermediate costError – 2 to 3 feet
Global Position Systems
Basic GPSSatellite System Only (3 of 24)Low cost – automobilesError – 100 feet
Satellites plus free beaconIntermediate costError – 2 to 3 feet
Satellites plus geostationary satelliteMore costlyError – 3 to 5 inches
Global Position Systems
Basic GPSSatellite System Only (3 of 24)Low cost – automobilesError – 100 feet
Satellites plus free beaconIntermediate costError – 2 to 3 feet
Satellites plus geostationary satelliteMore costlyError – 3 to 5 inches
Satellites plus base station nearbyCostly ($18,000 in 2006)One inch or less
Guidance and Automatic Steering Adoption
Most systems use GPS Payback
Improve productivityIncreased forward speedReduced crop inputsReduced operator fatigueAbility to operate longer hours
(darkness) Simple installation – 30 minutes Lower cost in recent years
Example of a Light BarLocated in front of
operator
All lights on in test mode
Green light – acceptable areaYellow light - caution areaRed light - unacceptable
Light Bar
Right most green light is on:Driving to right of center but acceptable(error increment can be adjusted)
Another Display SystemGreen rectangle represents front end of tractorand angle of line indicates error (magnitude of error also displayed)
Track Error
No Error
Another Display System
Green rectangle represents front end of tractorand angle of line indicates error (magnitude of error also displayed)
Track Error Track 2 ft.
No Error Small Error
Audio alarm when error occurs
Another Display SystemGreen rectangle represents front end of tractorand angle of line indicates error (magnitude of error also displayed)
Track Error Track 2 ft. Track 5ft
No Error Small Error Large Error
Audio alarm when error occurs
Transmissions for Mobile Equipment Gear
Speed changes in stepsSingle power transmission pathEfficiency at part loads dependent on the number of
gears Hydrodynamic
Automotive transmission Infinitely variableNot adaptable to high torque
Hydrostatic Infinitely variable Inefficient
Infinitely/continuously variablePower split in the transmissionElectronic control of transmission and engine for most
efficient operation
Background-Gear Transmissions
Early Tractors had one or two forward speeds, one reverse
More forward speeds were added Speed change without clutching-torque
amplifier Synchronized transmission Shifting on the go Infinitely/continuously variable transmission
Tractor Engine and Driveline for Two Wheel DriveSingle path for the flow of power through transmission
Engine
Clutch
Transmission
Differential
Axles
Infinitely/Continuously Variable Transmission
Power is directed into two pathsPlanetary gear systems facilitates thisPower from the two paths are merged
Basic CVT/IVT Transmission
Planetary Gear Set(power split)
Carrier
Sun Fixed path
Ring
2 gears
VariablePathInput
Output
Basic CVT/IVT Transmission
Planetary Gear Set(power merge)
CarrierFixed path Sun
2 gears
VariablePathInput
OutputRing
IVT/CVT Characteristics
• Hand control for forward, reverse, speed changes and stopping
• Smooth, seamless shifting• Unlimited speeds from 0.03 to 26 mph (Deere)• Improved fuel economy at reduced load• Reduced load-maintain forward speed with
changing engine speed• Need for feet only to start the tractor engine • Cost – $9780 (right side), $10,490 (left side)
Suspension System Goals
Improve operator comfort and reduce long term health issuesReduce vibration from traveling over rough terrainReduce vibration due engine and drive train
vibration
Improve tractor performanceReduce the potential for power hop on FWD and
FWA Improve contact between wheels and soil surface
Background on seat suspension
First tractor operators had to standSeats rigidly attached to tractor chassisSpring supported seats-passiveSpring plus shock absorbers -passiveAir suspensions seats-passiveActive suspension seats
Control Valve Assembly
Auxiliary Air Reservoir
Controller
Position Sensor Accelerometer
Actuator
Figure 2. John Deere Active SeatSource: Dufner and Shick, Deere
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
Acceleration, ft/sec-sec
Cab Input Typical AirSuspension
ActiveSuspension
John Deere Active SeatSource: Dufner and Shick, Deere
Tractor chassis suspensionMore beneficial for the higher speedsFront axle suspension – DeereFront and rear axle suspension - Fastrac
Tractor chasis suspensionMore beneficial for the higher speedsFront axle suspension – DeereFront and rear axle suspension - Fastrac Reduces potential for power hopImproved performance with FWA tractor
Concluding remarks
Guidance and auto-steerIVT/CVT
Fuel savingAutomatic shift up-throttle back
Suspension SystemsSeatCabChassis