The objective of the paper was to determine the level of circumferential stress in a wall of an open milk tank and to assess the tank wall degree of utilization according to the FKM Guideline calculation algorithm − Analytical Strength Assessment of Components, Made of Steel Cast Iron and Aluminium Materials in Mechanical Engineering. (German: FKM – Forschungskuratorium für Maschinenbau). The stress level in the tank wall was determined based on analytical calculations and numerical method using the FEA – Finite Elements Analysis. Numerical calculations were made in FEMAP with NX NASTRAN Solver (NASTRAN – NASA Structure Analysis). Similar stress values were found using two independent calculation methods. The difference between obtained stress values does not exceed 2%. Based on the FKM algorithm, the safety factor jges = 1.4 and static capacity of the tank wall ask = 19.7% were calculated.
The objective of the paper was to determine the impact of the shearing speed and cultivator tines flexibility on the vertical forces value. The study was carried out in field conditions in sandy clay soil and the average moisture of 11.2%. The vertical forces acting on four “s” tines with flexibility of 0.0061; 0.0711; 0.0953 and 0.1406 m∙kN−1 were measured. Tines were ended with a cultivator point with the curvature radius of 0.17 m. Measurements were made for four shearing speeds (1.0; 1.7; 2.4 and 3.0 m·s−1) and the shearing depth of 11 cm. A stand for measurement of forces acting on soil shearing farm tools in field conditions was used. It was concluded that the shearing speed caused a linear increase of the vertical force but the growth gradient does not depend on the tines flexibility. It was also concluded that the increase in flexibility causes an initial increase and then decrease of the vertical force, which was described with the second degree parabola equation. Flexibilities, at which extremes of courses occur, grow along with the reduction of the shearing speed.
The research concern selected traction properties of Massey Ferguson 7475 wheeled tractor, which were carried out on various deformable surfaces i.e. soil: after ploughing, sodded and with rye fore crop. The impact of driving speed on tractive power and force with 2WD and 4WD drive was investigated. Physical and chemical properties of soil during testing were characterised by moisture, compactness and maximum shearing stresses. Studies on traction properties were carried out with the use of two tractors: Massey Ferguson 7475 and New Holland 5040. During measurements, tractors were connected with a tow rod, where a strain force transducer was mounted. The stand enabled also measurement of theoretical speed. As a result of analyses of the obtained results, characteristics of tractive force and towing power as a function of slip were made. The tests confirmed that the use of four-wheel drive is unjustified because it improves these tractive parameters of a tractor. It was reported that the maximum force and towing power are generated for the lowest values of slip which is equal to 0.1 on the sodded surface. However, value of this power is the lowest in comparison to other surfaces. The highest value of the adhesion coefficient was reported on soil with rye fore crop.
The paper presents research results on the effect of cutting depth and speed on the resultant force tilt angle and location of its application point on a flexible tine ended with a cultivator point. The studies were carried out in field conditions in sandy clay with the gravimetric moisture of 11.2% and volumetric density of 1470 kg·m−3. Tines whose flexibility coefficient was 0.0061; 0.0711; 0.0953 and 0.1406 m·kN−1 were used. It was found out that that the resultant force tilt angle raises at the increase of the cutting speed and drops at the increase of depth but this angle and its gradient at the increase of the cutting depth grow along with the decrease of the flexibility coefficient of tines. The increase of the cutting speed and depth causes the decrease of both the distance of the resultant force application point on the tool from the bottom of a furrow and a proportion of this parameter to the cutting depth. The courses of the distance of the resultant force application point on the tool from the bottom of a furrow and courses of proportion of this parameter to the cutting depth as the function of cutting do not differ significantly for tines with higher flexibility coefficients while for the most rigid tine values of these parameters and their gradients are higher. All obtained courses of the analysed values as a function of depth and cutting speed were described with regression equations.
The paper presents the outcomes of the research on the impact of shearing depth and flexibility of cultivator tines with cultivator points on the value of vertical forces acting thereon. The object of the research consisted in “S” tines with the flexibility coefficient of 0.0061; 0.0711; 0.0953 and 0.1406 m∙kN−1. The investigations were carried out in field conditions in sandy clay soil with moisture of 11.2%. The forces were measured for the assumed shearing depths which were 5, 9 and 13 cm at the shearing speed of 3 m∙s−1. A stand for measurement of forces acting on soil shearing tools in the field conditions was used. It was found out that the increase of the shearing depth causes a linear increase of the vertical force, but the force gradient decreases with the growth of the tine flexibility. Moreover, it was found out that the increase of the tine flexibility at the beginning causes the increase and then the decrease of the vertical force regardless the shearing depth. The impact of flexibility on the vertical force value was described with the parabola equation. The tines flexibility, at which the highest value of vertical force may be expected, grows with the reduction of the shearing depth.
A liner is the only part of the milking unit which has a direct contact with a cow’s teat. It ensures a correct circulation of body liquids in a teat with its suitable massage and creates conditions for a teat to open and milk to flow out and maintains a milking cup on a teat. The result of the last task is generation of a suction force that sucks a teat into a liner. During milking, when a cup is placed on a teat, counter forces are generated that try to remove a liner from a teat and forces that cause that a teat moves up to a liner producing a phenomenon of “a climbing cup”. Forces that tend to separate a teat from a liner depend on the mass of a milking cup set and the value of the friction force. A counter force that tends to suck a teat into a liner is proportional to the level of negative pressure in a liner and the surface of cross-section of a teat that is subjected to negative pressure. We should also assume that also the structure of a liner will influence this force. The paper presents results of the laboratory tests on the impact of the shape of the cross-section of a rubber core and construction solutions of liners on the vacuum force of a liner when a teat is sucked into a teat chamber. Eight liners, popular in milking machines used in our country were used in the tests. Various penetrations of a teat (50, 62, 75 and 100 mm), working pressure (25-55 kPa) and a working stage of the milking cup were additional variables. In order to determine whether and what is the degree of the impact of variability sources on shaping the suction forces of a liner, a static processing of results was carried out using a multi-variance analysis. It was proved that at the significance level of α=0.05, the source of variability assumed in the experiment in the form of the liner shape, negative pressure and penetration affected the analysed sizes, i.e. Average values of suction forces in the suction phase (Fws) and massage phase (Fwm). The investigation of the impact of the rubber core part on the determined values of the suction force in the function of variable negative pressure proved that at teat penetration of 50 and 62 mm (the most popular lengths of teats in milked cows), the lowest suction force was observed in case of a liner with a triangular cross-section, slightly bigger with a square cross-section and the highest suction force is generated by round and oval liners.