Off-Road Equipment Management TSM 262: Spring 2016 LECTURE 6: Tractor Performance III Off-Road Equipment Engineering Dept of Agricultural and Biological Engineering achansen@illinois.edu

Homework and Lab

Class Objectives Students should be able to: Calculate the draft force and drawbar power for an implement Understand the scope and meaning of the information provided in a Nebraska tractor test report

Draft Force for Implements ASAE D497.7 - Section 4 Draft data reported as force in horizontal direction of travel Functional draft (soil and crop resistance) and draft required to overcome rolling resistance of implement included (one exception) Draft for implements operating at shallow depths is primarily function of implement width and speed Draft for tillage tools operating at greater depths also dependent on soil texture, depth and geometry of tool

Calculation of Draft Force D=Implement draft, N F=dimensionless soil texture adjustment (table 1 ASAE D497.7) i=1 for fine, 2 for medium, 3 for coarse textured soils A, B, and C= machine-specific parameters S=field speed, km/h W=Machine width, m or number of rows or tools T=Tillage depth, cm, 1 for minor tillage tools and seeding implements

Calculation of Draft Force A, B, C function of tillage tool design A – function of soil strength B and C – related to soil bulk density Soil categories Fine – high in clay content Medium – loamy soils Coarse – sandy soils Note: expected range of variation (±%) given in table 1 D497.7 due to differences in machine design, machine adjustment, machine age, and site-specific conditions including soil moisture and residue cover

Calculation of Drawbar Power Power = Force x velocity Pdb = (D x v)/3.6 D=implement draft, kN v = travel speed, km/h (refer to Table 3, D497.7)

Class Problem A farmer is using a field cultivator for secondary tillage in a loamy soil. The number of tools is 72, the travel speed is 12 km/h, and the tillage depth is 5 cm. Estimate Implement draft Drawbar power Equivalent PTO power from the MFWD tractor

Class Problem-Solution Implement Draft Drawbar Power

Class Problem - Solution Equivalent PTO power for MFWD tractor

Tractor Performance Where can we find information about tractor performance? Nebraska tractor test reports http://tractortestlab.unl.edu/ Refer to example

What is in a Nebraska test report ? PTO performance Max power and fuel consumption Drawbar performance Ballasted Unballasted Tractor sound level in cab and bystander in high gear Three point hitch performance / Hydraulic power performance Hitch dimensions Reports in English and SI units Picture of the test tractor N, rev/min Pb, kW Max. power Gov. max (rated)

Machine data + test conditions Test location and date Tractor manufacturer Fuel, Oil and operating duration Engine specs Engine operating parameters Chassis Repairs and adjustments Notes and remarks

Use of Nebraska test data PTO test direct usable power (~90% engine power) Weather conditions can give 8% change Drawbar tests on concrete, horizontal for fair comparison among tractors How to translate that to a soil condition, integral/semi-mounted/towed implement ?

Drawbar Tests in Selected Gears How do they control drawbar load during a test?

Basic Tire Design Tire Size 34.00 - R25, 8 Ply Rating Nominal Section Width, bni Nominal Rim Diameter, dnri Radial

Tire Specification: JD 9620 Tire Pressure psi Six 480/80R46;***;12(85) Tire Pressure kPa No. of Tires Radial Nominal Section Width, mm Aspect Ratio Ht/width % Nominal Rim Diameter, in Index of Radial tire strength

Tire Construction Bias ply – diagonal belts Radial ply – belts go straight across Belts included to provide increased rigidity for better tread life

Class Exercise