Biological Systems Engineering


First Advisor

Santosh K. Pitla

Second Advisor

Roger M. Hoy

Date of this Version



Roeber, J.B.W. (2016). Tractor Measurement and Data Acquisition System for Hydraulic Power, Draft Force, and Power Take-off Torque (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 Santosh K. Pitla & Professor Roger M. Hoy. Lincoln, Nebraska: May, 2016.

Copyright 2016 James B. W. Roeber


Numerous advancements in machinery performance of agricultural tractors have been made in recent years. The Organisation for Economic Co-operation and Development (OECD) tests predetermined points (e.g., maximum power and torque) for drawbar, Power Take-Off (PTO), and hydraulic power as separate tests for tractor performance. Testing methods with the tractor operating at a steady state have been done for years, which were uncharacteristic of agricultural tractor operations in field conditions. As part of this thesis work, field usable data acquisition systems (DAQs) were developed to record implement energy consumption (e.g., drawbar loading, PTO torque, and hydraulic power). The system used LabVIEW software and National Instrument’s compact data acquisition systems (cDAQs) to record data from instrumentation measuring drawbar, PTO, and hydraulic loads. Data were collected and verified in accordance with OECD standards at the Nebraska Tractor Test Lab (NTTL), an official OECD testing facility. Requirements of the systems were: implementation of each system on multiple machines with minor alterations, minimal changes to the tractor, and equivalent data compared to that recorded by the NTTL testing devices and procedures. Manufacturer’s calibration information along with standardized testing equipment used to tune NTTL testing devices were used to verify that the system would provide data in conformance with OECD testing procedures. The hydraulic system was verified with varying hydraulic line curvatures near the sensors that provided data within a 1 percent difference of the actual hydraulic power. Drawbar tests included calibration of a strain gage instrumented drawbar which recorded loads within 0.67 kN of the calibration fixture. Track testing of the drawbar resulted in measured differences of less than 1 kN with the NTTL load car. For PTO measurements, a power take-off calibration was conducted using a commercially available torque transducer. No statistically significant differences were found between the torque values of the PTO transducer and the dynamometer. The differences in torque values ranged from 3 N∙m to 23 N∙m.

Advisor: Santosh K. Pitla and Roger M. Hoy