Search Results

Data envelopment analysis (DEA) is used to examine the efficiency of 74 front wheel assist agricultural tractors from three U.S. manufacturers. The outputs of drawbar horsepower and power takeoff horsepower are modeled in a constant returns-to-scale framework using three productive performance inputs (fuel consumption, slip, and center of gravity), and one price input, namely, retail tractor price. The results suggest that by and large, John Deere tractors are more DEA efficient than their competitor's tractors. However, competitor's tractors that are DEA efficient are most often the top benchmarks for DEA inefficient tractors. These results suggest that while John Deere appears to produce many quality tractors, competitor's like CNH and AGCO produce a few tractors that may be of even higher quality.

An exploratory concept for a chassis suspension system for improving the operator ride comfort of an agricultural tractor is presented in this paper. The first section of the paper describes the criteria and concepts that have been incorporated into the design of a hybrid leading and trailing arm chassis suspension system. The second section of the paper discusses the evaluation of this suspension system and its parameters by simulating nine (9) different tractor and nine (9) different tractor-plow models, derived from the various combination of suspension configurations and operator cab locations. A generalized mechanical system simulation program is utilized to predict the dynamic linear transfer function behavior of each vehicle model. With frequency domain analysis techniques and the Fast Fourier Transform (FFT) algorithm, the dynamic vehicle response to the ISO 5007 Smooth Track excitation is computed.

An analytical study of the dynamic behavior of agricultural tractor-trailer combinations is conducted to investigate the stability and handling characteristics. Equations of motion reflecting the characteristics and parameters of the combination in terms of stability and handling are developed. The influence of changing the combination operating and design parameters on the lateral stability of the system is investigated with an eigenvalue analysis technique and a time-domain integration technique. The simulation results showed that forward speed of the combination and the properties of the trailer substantially affect the lateral stability of the tractor-trailer combination.

A kinematic model for studying the maneuverability of an off-road tractor/double-axle trailer combination has been formulated. The influence of steering inputs from the tractor and the trailer front axles on the system's maneuverability in terms of lateral displacement and rotational motion during the turning process is studied by conducting computer simulations using the LOTUS spreadsheet program. A lane-change problem is presented to demonstrate the computational procedure and to illustrate the application of the kinematic model.

Computer simulation modelling techniques are basic engineering tools to investigate and predict the performance and mobility of agricultural tractors. Analytical methodologies developed by researchers to simulate and evaluate the terrain-operator-agricultural vehicle system and its subsystems are described. The techniques are classified as models and methods describing the subsystem interactions and relationships and the overall tractor-soil-implement system. The subsystem models and methods include: soil mechanics) the soil-wheel interactions, the soil-track interactions, the vehicle mechanics relationships, the soil-implement interactions, and the power train and hitching relationships. These models and methods were developed by various researchers as a means to optimize the tractive performance of the tractor by parameter sensitivity analyses.