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Studies on Deflection of Main Frame Members of a Row Crop Cultivator

M. A. Mazed
Head of Division
Bangladesh Agricultural Research Institute, Gazipur.

Abstract/ Executive Summary:

The function of a row crop cultivator depends greatly upon the extent of the deflection of its major frame members. An experimental investigation was made to determine the deflections of front and rear tool bars of a standard row crop cultivator under the simulated field conditions. The values of experimental deflections were compared with that of theroretical deflections determined using classical theories of elasticity.

Keywords: Crop, Main frame,

Location: Bangladesh Agricultural Research Institute.

Start Date:

End Date:

Program Area: Farm Mechanization

Commodity: Performance evaluation

Objectives:

1. Determination of elastic deflection of the front and rear tool bar of a cultivator frame in horizontal and vertical direction by applying the forces equal or proportional to normal maximum service load on the front and rear row of tines under simulated field conditions.

2. Comparison of experimental deflection with that obtained using classical theories of elasticity.

Methodology:

The cultivators are usually linked with a tractor through three point hitch system. From theoretically calculated normal maximum service loads, the force acting at hitch points were calculated at the National College of Agricultural Engineering at Silsoe, England. On the basis of the magnitude of forces the members of the rig assembly were calculated from the British Standard structures. The rig was constructed from 50.8 mm x 50.8 mm x 4 mm hollow box section. A device was designed such that it would simulate the field conditions. Actually in the field, the force on each tine seldom remains constant. The magnitude, direction and point of action of the force depends upon the uniformity of soil surface, homogenity of the soil body, rigidity of the cultivator frame and interference of one tine on the path of another. The normal maximum service load at spring release was 3 kN on each of front tines and 1.825 kN on each of rear tines. The point of action and direction at force on each tine of the rear row were determined for the case of maximum loading. The normal maximum service load at spring release was 3 kN on each of front tines and 1.825 kN on each of rear tines. The point of action and direction of force on each tine of the front and rear row were determined for the case of maximum loading. So it was decided to apply force on each tine by passing a thin steel wire rope around each tine. A solid bar of rectangular section was placed on two 1-beams perpendicular to its length. Then fixing small pulley on the solid bar the wire rope was passed around the pulley and the tines. The distance a of each solid bar from each row of tines was such that the angle of inclination of the rope should be 23° which was the inclination of the resultant soil force on the tine. The force was applied by pulling the wire rope from both ends of the solid bar. The force was measured with the help of statimeter.

For experimental purpose the tool bars were designated. The deflection measuring device was placed on the frame and the dial indicators at different points to measure the deflections in different directions were set correctly. At outset, the dial indicators were used to define the unloaded location of the tool bar. The forces of 200 N at the front row of tines and 122 N at the rear row of tines were applied through the wire rope system, the effect of friction on the rope being eliminated by vibration of the assembly. The effects on dial indicators due to loading were noted. The above procedure was repeated at the loads of 400 N, 600 N and 800 N at the front and correspondingly 244 N, 366 N and 486 N at the rear row of tines. The whole experiment was replicated three times.

Source of Information: Bangladesh Journal of Agriculture, Vol-3, No-1, June-1978,Page:265-270

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

From the results obtained it was revealed that the values of deflections obtained experimentally were less than the theoretical values calculated previously. The percentage difference was observed to vary from point to point, direction to direction and from position to position of the tool bars. The range of difference varied from 2.56% to 2.67% for direction and 2.67% to 7.6% for the position of the tool bars. The differences, however, may be analyzed in the light of certain unavoidable circumstances coming into play during both the theoretical calculation and experimental investigation. The values of bending deflections of the cultivator tool bars were found very low during experimental investigation and it may also be concluded that the bent stems should not run wide and chop out plants during operation as indicated.

Knowledge Management: Journal