Drawbar Parameters of Tractor with Prototypes of Driving Wheels and Standard Tyres

The paper presents the main drawbar parameters of tractor (drawbar pull, drawbar power and wheels slip) operating in a grass plot and evaluates the utilization of specially modified tyres with spikes. These prototypes of driving wheels were designed at the Department of Transport and Handling of the Slovak University of Agriculture in Nitra. The designed mechanism with spikes is mounted on standard tractor tyres, in which grooves were made. Spikes are hidden in grooves during transportation on a route. On the grassy landscape or soil, the spikes are ejected in order to improve the drawbar parameters. During operation, the drawbar pull and the rotation speeds of wheels were measured, whereupon the wheel slip was calculated. Results show the highest increase in tractor speed at the second gear and high load in utilized prototypes of the driving wheels (1.89 km·h-1) in comparison to standard tyres (1.10 km·h-1). Measurements also demonstrate the highest improvement of drawbar power under the aforementioned conditions in case of tractor with prototypes of driving wheels (1,719.87 W) in comparison with tractor using the standard tyres (1,061.57 W).

Methane/Gasoline Bi-fuel Engines as a Power Source for Standard Agriculture Tractors: Development and Testing Activities

Promoting energy efficiency in agriculture means supporting economic growth by reducing both pollution and greenhouse gas (GHG) emissions while minimizing waste and the inefficient use of natural resources. Biomethane presents an interesting option given its possibility to be produced from livestock waste or other organic residues, with GHG emission savings ranging from 84% to 86% (wet or dry manure). Moreover, experiences with methane-fueled engines are widely available, thus leading to considering the possibility of using such a fuel in the agricultural sector as well. The aim of this research was to develop a first-generation tractor prototype provided with a commercially available bi-fuel engine adapted for the purpose and tested both in laboratory and field conditions. The main design aspects are depicted while the performance results show similar values of engine power and torque (87 kW maximum power for the diesel fuel tractor and 88 kW for the methane-fueled version; 1172 Nm maximum torque at 550 min-1 for the methane and 1155 Nm at 400 min-1 for the diesel tractor) with an autonomy of the methane prototype which is, at present, 40% of a comparable standard tractor. The possible role in farm fleet is also presented. Keywords: Agricultural machinery, CNG, Gaseous bio-fuels, Renewable fuels.

A Robotic Prototype for Spraying and Pollinating Date Palm Trees

Spraying and pollinating date palm trees is currently done manually by a team of three workers from a platform lifted 18 meters or more above the ground. This method is extremely unsafe and many accidents have happened due to lack of stability when the platform is in a lifted position. Alternatively, date clusters are occasionally sprayed by a large pressurized sprayer directly from the ground, a method that is highly unselective and environmentally harmful. In this paper we present the concept of an automatic apparatus that can effectively and accurately spray and pollinate date clusters from a robotic apparatus mounted to a standard tractor operated by a single driver. The apparatus consists of a robotic arm and computer controlled sprayer, guided by a computer vision system that detects and localizes date clusters with a camera. This system will minimize risk of injury, significantly save manpower (from three to one person per team), and deliver the spray with maximum accuracy thereby reducing chemical disposure. A small scaled prototype has been built and is currently under preliminary experiments.

Influence of tractor—trailer interaction on assessment of road damaging performance

The influence of dynamic interaction between tractor and trailer on the assessment of the road damaging performance of heavy goods vehicles is investigated using simple mathematical models. Tractor and trailer damage indices are used to quantify the ‘in-service’ road damaging performance of a simulated fleet of vehicles with parametric variations typical of highway traffic in the United Kingdom. Simulated results of assessment tests on individual tractor—trailer combinations are correlated with the performance of the simulated vehicle fleet. The main aim is to establish the characteristics of a ‘standard’ semi-trailer to be used in the assessment of tractors, and a ‘standard’ tractor for testing semi-trailers. It is found that measurement of suspension ‘frequency’ gives the poorest correlation with the damage indices, while the ‘dynamic aggregate force coefficient’ gives the best correlation. Correlation achieved when assessing trailers is higher than when assessing tractors. Optimum specifications for standard test tractors and trailers to maximize test accuracy are determined.

Review Paper: Assessing ‘road-friendliness’: A review

This paper is concerned with assessing the dynamic tyre forces generated by articulated heavy goods vehicles for road damaging potential. Various factors are discussed, including: (a) general testing methodologies; (b) road damage issues such as ‘spatial repeatability’ of dynamic tyre forces and road damage criteria; (c) vehicle response issues, such as test duration and sampling details, road roughness, testing speed, wheel-base filtering, tractor—trailer interaction, suspension maintenance and ‘indirect’ testing methods; and (d) implementation issues. It is concluded that the most practical method of assessment testing would be to use a ‘type approval’ test to measure the vehicle's peformance when coupled to a standard trailer or tractor unit, combined with anual inspections of hydraulic damper integrity. The type approval procedure should use simple single-axle laboratory tests to estimate the parameters of a generic mathematical model of each vehicle unit. Numerical simulations of the tractor and standard trailer (or trailer and standard tractor) should be used to determine the vehicle's response to a variety of typical road input conditions. These responses should than be assessed using realistic road damage criteria to determine an ‘in-service’ road damage index.

Effect of Light during Cultivation on Weed Emergence

This experiment was conducted to determine whether light conditions during cultivation affect the number or species composition of emerging weeds. Plots were cultivated on 31 May 1996 under the following light conditions: 1) Ambient nighttime light (full moon) plus tractor headlights, 2) ambient nighttime light plus tractor headlights covered by transparent green film (green tractor lights), 3) ambient nighttime light with no tractor headlights, 4) ambient mid-day light. A fifth treatment was not cultivated at all, but was treated with glyphosate on 31 May to kill emerged plants. Results discussed below are based on weed densities determined 3 weeks after cultivation. Cultivated plots had more broadleaf weeds than uncultivated plots (119/m2 vs. 40/m2). Annual grass populations were the same in cultivated and uncultivated plots (20/m2). Common lambsquarters (Chenopodium album) and carpetweed (Mollugo verticillata) were the most common annual broadleaf weeds, representing more than 80% of the annual broadleaf population in cultivated plots. Light conditions during cultivation did not influence the total number of broadleaves, number of annual grasses, or total number of weeds emerging. Lambsquarters emerged in greater numbers after daytime or night cultivation using green tractor lights (48/m2) than after night cultivation using standard tractor headlights (32/m2). These results suggest no practical benefit to night cultivation for reducing overall weed density. A similar study in 1995 led to a similar conclusion. Although measurable effects of light conditions on weed emergence were observed in both years, the magnitude and consistency of the effects were not enough to suggest changes in cultivation practices without further research.