Research in Agricultural Engineering, 2003 (vol. 49), issue 2

Pressure in the hydraulic system of three point hitch of tractor equiped with electrical and mechanical control

I. Petranský, Š. Drabant, J. Ďuďák, A. Žikla, I. Grman, J. Jablonický

Res. Agr. Eng., 2003, 49(2):37-43 | DOI: 10.17221/4950-RAE  

The goal of the measurement of the tractor ZTS 164 45 equipped with digital electrohydraulical control EHR-D BOSCH during ploughing with ploughs KUHN (4 bottoms) and 5 PHX 35 (5 bottoms) was to obtain time dependent states of pressure in the hydraulic system of the three point hitch of tractor. From the point of view of comparison of obtained results testing conditions were determinated with respect to physical and mechanical properties of soil such as soil volume mass, soil humidity, penetration resistance and shear resistance of soil. Beyond these measurements also measurements of operation parameters as a ploughing depth, ploughing width, working...

Comparison of two possibilities for mowing machine material feed rate measurement under laboratory conditions

F. Kumhála, J. Mašek, V. Prošek

Res. Agr. Eng., 2003, 49(2):44-49 | DOI: 10.17221/4951-RAE  

The impact of materials and conditions (parameters) changes on mowing machine material feed rate measurement accuracy were measured under laboratory conditions. The influence of crop variety, crop maturity and moisture, and intensity of conditioning were tested. The impact of the changing parameters in two measurement methods (based on torque-meter and/or on impact plate) was studied. Eight files of torque-meter and/or impact plate measurement were obtained during our experiments. Statistical analysis was used for data evaluation. Two-sample comparisons were used for torque-meter measurement. It is evident from that evaluation that changing crop variety,...

Approximation of bruise spot volume in pears in plots against deformation parameters

J. Blahovec, V. Mareš

Res. Agr. Eng., 2003, 49(2):50-55 | DOI: 10.17221/4952-RAE  

Pears of different varieties were compressed between two flat rigid plates in loading/unloading tests. The bruise spots appearing after room temperature incubation were analysed manually, and bruise spot volumes were determined. The main parts of the paper discuss mathematical approximation of total bruise volume versus two deformation parameters defined in previous papers: hysteresis losses and degree of elasticity. The polynomial of the second order was used for this purpose, but success of this method depends on including some part of not-bruising results in the analysis. Characteristic values of hysteresis losses and degree of elasticity were used...

Determination of elastic parameters of grain with oedometric and acoustic methods

M. Stasiak

Res. Agr. Eng., 2003, 49(2):56-60 | DOI: 10.17221/4953-RAE  

Values of modulus of elasticity E and Poisson's ratio were determined with two methods adopted from geotechnique. First approach used was a method proposed by Sawicki (1994). This type of examination was applied to estimate values of E and v for wheat and rapeseed beddings for five levels of moisture content ranging from 6% to 20%. Modulus of elasticity E of wheat was found to decrease with an increase in moisture content. With the second method values of E were determined based on measurement of shear wave velocity. Tests were performed for bedding of wheat and rapeseed under equilibrium moisture content....

Experimental method for determination of the pressure distribution in granular solids

R. Rusinek

Res. Agr. Eng., 2003, 49(2):61-64 | DOI: 10.17221/4954-RAE  

This paper presents two methods of determination of pressure distribution in rape seeds. The study utilized hydraulic pressure sensors with active rubber face and stress state transducer with six duralumin face sensors. This project utilized methodology well known from soil mechanics for determination stress in plant granular material. The hydraulic pressure sensors has been design to measure normal pressure in granular material. The stress transducer has been designed to measure pressure in six different directions, which orientation enable to calculate the stress state from the pressure measurements. The project enclose to design calibrations procedure....