Michael F. Kocher

PREDICTING TRACTOR FUEL CONSUMPTION

Reports from the Nebraska Tractor Test Laboratory (NTTL) show improved fuel efficiency during the past 20 years. A 4.8% decrease in average annual specific volumetric fuel consumption for the data used in theASAE Standards was shown. Using fuel consumption and power data from the NTTL reports, new equations for fuel consumption were established that predict fuel consumption for diesel engines during full and partial loads and under conditions when engine speeds are reduced from full throttle.

LABORATORY AND FIELD TESTING OF SEED SPACING UNIFORMITY FOR SUGARBEET PLANTERS

Five planter configurations were evaluated for seed spacing uniformity at three field speeds using a seed location method in the field and a laboratory method involving an opto-electronic sensor system. Planter seed spacing uniformity was described using the Coefficient of Precision (CP3) measure. Results showed that CP3 measures determined using the laboratory test method were significantly different from those determined using the field test method. This indicated the laboratory test method cannot be used to predict planter seed spacing uniformity in the field. Seed spacing uniformity determined in laboratory tests was higher than, or equal to, seed spacing uniformity determined in field tests. This indicated the laboratory test method may be useful to screen out planters or planter units with poor uniformity of seed metering. Field testing of the planters that perform well in laboratory tests must be conducted to adequately determine the seed spacing uniformity of those planters in the field. Results from laboratory and field tests could be useful in determining areas for improvement of planters or planter units.

OPTO-ELECTRONIC SENSOR SYSTEM FOR RAPID EVALUATION OF PLANTER SEED SPACING UNIFORMITY

An opto-electronic seed spacing evaluation system that measured time intervals between seeds and detected frontto- back location of seed drop events relative to the planter was used to rapidly determine planter seed spacing uniformity in the laboratory. The seed detection sensor for the opto-electronic system consisted of a rectangular photogate with 24 phototransistors receiving light beams from 24 LEDs opposite to them. The system also included circuitry to interface the photogate with a digital I/O board in a personal computer. The opto-electronic system was tested with three planter configurations. During the tests, the photogate was positioned beneath the seed drop tube in a position representing the bottom of the furrow, and directly above the belt of a grease belt test stand. Seed spacings obtained with the opto-electronic system were compared with measurements of the same seed spacings obtained from the grease belt test stand. The information on the front-to-back location of seed drop events relative to the planter significantly improved the electronic seed spacing measurements in all cases. Seed spacing measurements obtained using the opto-electronic system determining time intervals between seeds and front-to-back locations of seed drop events relative to the planter were strongly correlated (average r = 0.951) with the same seed spacing measurements obtained using the grease belt test stand. The opto-electronic system can be used instead of a grease belt test stand to rapidly obtain quantitative evaluations of planter seed spacing uniformity in the laboratory.

FIELD EFFICIENCY DETERMINATION USING TRAFFIC PATTERN INDICES

Field efficiency is an important criterion for determining field capacity during field operations and, indirectly, for making important machinery management decisions. Geographic location data gathered with a yield monitor during harvest and a data logger during planting were used to provide time-motion studies of equipment and operator productivity. This study used these spatial and temporal data to quantify field performance of a combine and a planter. Seven Nebraska fields were used to compare results from soybean and corn production systems. Fields that were relatively flat with straight rows were contrasted with contoured fields with slopes of 3% to 5%. Two unique traffic patterns in fields with a center pivot were compared. Four traffic pattern indices were developed and averaged across each field to indicate the steering behavior (or adjustments) made during field operations. Geo-referenced data were used to predict field efficiency for various traffic patterns. Of the four indices compared, the average steering angle (.) and its standard deviation had the strongest association with field efficiency with Pearson correlation coefficients of -0.654 and -0.664, respectively. The average steering angle for contoured traffic patterns were two to four times in magnitude that of straight- and gently curved-row traffic patterns. The steering angle index gave valuable information about field operating conditions but differences in data recording methods and operational characteristics imposed limitations on statistically appropriate comparison analyses.

Development of an Instrumented Deep−Tillage Implement for Sensing of Soil Mechanical Resistance

Variable-depth tillage has the potential for economic and environmental benefits to modern crop production. Varying tillage depth according to local soil conditions prevents the waste of energy and preserves soil ecology. A prototype instrumentation system was developed based on a conventional implement for deep tillage. It was equipped with two load cells and two sets of strain gauges for sensing the load applied to the implement during tillage. Two linear pressure distribution models (full and redundant) were used to describe the change of soil mechanical resistance with depth. These models were then used to compare estimates of soil mechanical resistance applied to the point of the deep-tillage implement based on predicted and measured values. Field evaluation was conducted to illustrate the system’s performance in two experimental sites. In both cases, instrument predictions corresponded with soil profile measurements obtained using a standard cone penetrometer. The developed system may become a part of variable-depth tillage equipment after an algorithm for a closed-loop tillage depth control is developed.

TESTING FUEL EFFICIENCY OF A TRACTOR WITH A CONTINUOUSLY VARIABLE TRANSMISSION

A John Deere 8530 IVT tractor (Waterloo, Iowa) with a continuously variable transmission (CVT) that could be operated in automatic (CVT) or manual (fixed gear ratio) mode was tested for fuel consumption at a setpoint travel speed of 9 km·h-1 with 17 different drawbar loads. Linear regression analysis results showed that with the throttle set to maximum in both transmission modes, operating the tractor with the transmission in the automatic mode was more fuel efficient than operating with the transmission in the manual mode when the drawbar power was approximately 78%, or less, of maximum power. When load transition portions of the data were filtered out, there was no significant effect of load sequencing in the remaining data. On the other hand, there was a noticeable effect of travel direction which could occur due to a minor slope of the test track in the direction of travel. Testing of more tractor models from different manufacturers and at different travel speeds is needed to determine if these results can be applied to different tractor models produced by the same and/or other manufacturers.

Testing Fuel Efficiency of Tractors with both Continuously Variable and Standard Geared Transmissions

A John Deere 8295R IVT tractor with a continuously variable transmission (CVT) and a John Deere 8295R PowerShift (PST) tractor (Waterloo, Iowa) with a standard geared transmission (GT) were tested for fuel consumption at three different travel speeds with six different load levels applied per speed. The JD 8295R PST tractor was tested both at full throttle (FT) and shifted up two gears and throttled back (SUTB) to achieve the same travel speed as at full throttle conditions. For each travel speed with each transmission mode, fuel consumption was determined to be linearly related to drawbar power. Linear regression results showed that the tractor with the CVT was more fuel efficient than the tractor with the GT at FT when the power was below 76% to 81% of maximum drawbar power depending on the travel speed. The results also showed that above 37% to 52% of maximum drawbar power, the GT at SUTB was more fuel efficient than the CVT equipped tractor. As travel speed increased, the percent of maximum power below which the CVT was significantly more fuel efficient than the GT at FT decreased slightly. Likewise, the percent of maximum power above which the GT at SUTB was more fuel efficient than the CVT decreased as speed increased. In order to determine differences in fuel consumption between the tractor transmission operating modes, testing with at least three loads and at least three travel speeds is recommended. Additional testing is needed on other models of tractors from other manufacturers to determine whether the trends found in this study pertain to all CVT equipped tractors or if they are specific to this tractor model and manufacturer.

FIELD SLOPE EFFECTS ON UNIFORMITY OF CORN SEED SPACING FOR THREE PRECISION PLANTER METERING SYSTEMS

The effects of field slope on planter seed spacing uniformity were evaluated for three different seed metering units (cell plate, finger pick-up, and flat plate) operating with medium round corn seed in a laboratory using the University of Nebraska planter test stand with an opto-electronic seed spacing sensor system. The metering units included a John Deere MaxEmerge™ Plus VacuMeter row unit with the standard cell corn plate, a John Deere MaxEmerge™ Plus VacuMeter row unit with the flat plate, and a John Deere MaxEmerge™ Plus row unit with the finger pick-up metering system. Planter seed spacing uniformity was measured using three parameters: ISO Miss index, ISO Multiples index, and Coefficient of Precision (CP3). Six replications for nine field slope treatments were conducted for each metering unit. The field slope treatments included: front-up (front of planter unit), front-down, right-up (right side of planter unit), and left-up each at field slope levels of 10% and 20%, and level.

Wide Tires, Narrow Tires

Tractive performance comparisons among five different size tires were made on two different surface conditions, a wheat stubble field and a tilled wheat stubble field. Radial 18.4R46, 20.8R42 and 710/70R38 radial tires; and bias 750/65-38 and 850/55-42 tires were used. Instrumentation to evaluate tractive performance was installed on a two-wheel drive and a mechanical front wheel drive agricultural tractor. Axle torques, drawbar pull, travel speed, and engine rpm were recorded for a series of drawbar pulls on the two soil surfaces. Tractive performance evaluations among the tires were made by comparing the relationships of dynamic traction ratio to slip, tractive efficiency to slip, and tractive efficiency to dynamic traction ratio. In general, narrower tires exhibited performance advantages over wider tires.

Granular particle linear flow velocity measurement using an electronic linear image sensor

Abstract A metal-oxide semiconductor (MOS) linear image sensor consisting of an array of 128 self-scanning, linear photodiodes was used to measure the velocity of falling grain. The sensor was used to obtain an image of the falling grain, wait a known time interval, and then obtain a second image. Comparison of the two images permitted determination of the position displacement experienced by the grain. Optical relationships were used to convert the image displacement to grain displacement. Grain displacement divided by the time interval yielded grain velocity. This paper addresses the sensor and data acquisition hardware, the digital signal processing software, calibration of the sensor, and velocity measurement. Average grain flow velocities ranging from 1 to 7 m/s were measured with less than 7% error. The sensor can also be used to measure the flow velocity of similar granular material such as pelleted feed or fertilizer.