Biological Systems Engineering


First Advisor

Roger Hoy

Date of this Version

Spring 5-2016


Melotz, G.W. (2016). AN EVALUATION OF AGRICULTURAL TRACTORS HYDRAULIC LIFT PERFORMANCE (Master’s thesis). University of Nebraska-Lincoln, Lincoln, NE


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Agricultural and Biological Systems Engineering, Under the Supervision of Professor Roger Hoy. Lincoln, Nebraska: May, 2016

Copyright (c) 2016 Grant W. Melotz


The current OECD Code 2 detailing the procedures for the hydraulic lift test of agricultural tractors, section 4.3, published lift values that were sometimes unattainable. The static weight of 2WD, two wheel drive, and MFWD, mechanical front wheel drive, tractors and the amount of lifting force have increased at a greater rate than the amount of static weight on the front axle. This increase in lifting force has led to a decrease in the percent of weight as the upward support force on the front axle of a tractor. Many of the 2WD and MFWD unballasted tractors tested at the Nebraska Tractor Test Laboratory (NTTL) since 1995 were discovered to have lift forces sufficient to raise the front axle off of the ground given the current maximum achievable lifting capacity measured during testing.

Equations for calculating the maximum realistic achievable lifting capacity of tractors were developed based on maintaining a minimum amount of upward support force on the front axle. A test to determine how much upward support force at the front axle was sufficient to maintain adequate steering control of tractors was developed. Operator feedback from this test determined that 20% of the total tractor weight as the upward support force on the front axle had significantly greater steering control when compared to 15%. A sample proposal was drafted to be sent to OECD to update the hydraulic lift test in Code 2 requiring limiting the maximum lifting force published such that a minimum of 0% of the total unballasted tractor weight as the upward support force on the front axle for 2-track tractors, and 20% for 2WD and MFWD, and 4WD tractors.

This proposal utilized a series of equations based on several different tractor characteristics to determine the maximum realistic achievable lifting capacity of agricultural tractors that were tested at OECD accredited test facilities. Ballasted weight configurations were also incorporated for maximum realistic achievable lifting capacity of tractors under this new proposal. A sample of what future publications with these changes could resemble was prepared for the John Deere 6150M tractor.

Advisor: Roger Hoy