Radoslav Majdan

Effect of Ecological Oils on the Quality of Materials of Hydraulic Pump Components

This paper presents the effect of three oil types on the quality of hydraulic pumps after testing on a special test bench. The quality of material of hydraulic pump components was evaluated on the basis of its wear. In the special test bench, hydraulic pumps were loaded by cyclic pressure with different oil types. There were tested a mineral oil-based liquid HV and two biodegradable types, i.e. a vegetable oil-based liquid HETG and polyalphaolefin oil-based liquid HEPR. The wear level of hydraulic pumps was evaluated on the basis of flow efficiency and the weight and roughness of internal components. Laboratory scales were used to measure the weight of hydraulic pump components. Results of measured roughness and weights have been graphically compared. We noticed the most significant material wear on bearings and slide plates. The highest loss of weight was observed in the hydraulic pump tested with the ecological oil HETG. The highest loss of flow efficiency (7.3 %) was measured with the same oil type. This paper shows differences in the wear of hydraulic pumps after testing with different types of oils on the basis of selected methods of technical diagnostics.

Evaluation of Fuel Consumption in Road Freight Transport

Abstract This paper deals with the importance of fuel economy in road freight transport. It provides the calculation of financial savings for fuel savings of 0.5 l per 100 km. In the subsequent part, some factors that influence the fuel consumption are specified, e.g. aerodynamic resistance, rolling resistance, and tyre inflation pressure. The effect of tyre inflation pressure on fuel economy has been tested on four selected towing vehicles. Based on the results obtained, it can be stated that tyre pressure has a great impact on fuel consumption. A one-bar pressure reduction of tyres can increase the fuel consumption by 0.5 l per 100 km.

THE EFFECT OF DRIVING WHEEL TYPE ON DRAWBAR PULL OF TRACTOR

This paper is focused on the possibility of increasing the drawbar pull of agricultural tractor on the soil and grass-covered surface. From our perspective, we have chosen one available and the cheapest way, i.e. steel boots for tyres of small tractors, and this was compared with a newly developed system of auto-extensible blades next to the wheel. The tractor with steel boots and auto-extensible blades reached a higher drawbar pull on average by 70 % in comparison with tyres.

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

Abstract 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).

Assessing the Technical Condition of Inspected Vehicles in Reporting Period

Abstract Vehicle emissions inspection represents a fast, relatively efective in terms of time and cost, and mainly comprehensive estimation of vehicle emissions. Procedurally, emissions inspection includes those inspection operations that focus not only on analysing exhaust gases but also on detecting the functionality and tightness of other engine components directly afecting the ecological friendliness of inspected vehicle‘s engine. Our study describes the results of vehicles inspected at an emissions inspection station for the reporting period. Based on the analysis of information obtained from the National Transport Authority of the Slovak Republic concerning the evaluation of vehicles according to individual categories, it can be alleged that the technical condition of vehicles of M1 and N1 categories is gradually improving.

Hydraulic Device for Simulation of Pressure Shocks

Abstract This work is focused on the design of a hydraulic device on which simulations of pressure shocks can be performed. The hydraulic device was constructed to allow simulations of pressure shocks transferred directly in operating conditions because simulation programs for hydraulic accumulators have only theoretical values while simulation on the designed hydraulic device enables obtaining specific readings directly in operating conditions that can be set. At the first control measurement on the hydraulic device, there occurred pressure shocks generated by the hydraulic device itself, these pressure shocks being undesirable in hydraulic circuits. In order to eliminate pressure shocks in the circuit, a diaphragm accumulator was added to the hydraulic device and was used to verify the function of simulating pressure shocks and eliminating undesirable pressure shocks. During the second control measurement on the hydraulic device, a reduction of unwanted pressure shocks was shown with the help of added diaphragm accumulator, thus the function of the hydraulic device to simulate pressure shocks was confirmed, which may also refect practical application in hydraulic circuits of mobile machines.

Design and Verification of Tractor Wheels Equipped with Automatically Extensible Blades

Abstract This paper focuses on the possibility of increasing the drawbar pull of an agricultural tractor on the soil and grass-covered surface. We have compared the tractor tyre traction properties with a newly developed system of automatically extensible blades next to the tractor drive wheel tyres. The tractor with wheels equipped with auto-extensible blades reached a higher drawbar pull at an average of 70 % on the soil and 80 % on grass compared to tyres.

Deviations in Fuel Consumption Measurement of Lorries

Abstract Our study focuses on individual methods of measuring the fuel consumption of lorries. We have verified the difference between the consumption calculated from fuelling records and consumption listed by the Infomax information system. Based on obtained results, we can state that the difference between presented consumption measurement methods reached the maximum value of 5 %.