Theoretical research into the stability of motion of the ploughing tractor-implement unit operating on the ‘push-pull’ principle
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Kuupäev
2017
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Abstrakt
The reduction of power consumption in the ploughing operations can be achieved by
way of improving the grip properties of the implement-carrying tractors, which is facilitated by
setting up ploughing units for operation on the ‘push-pull’ principle. The aim of the current
research is to substantiate the set-up and parameters of the ploughing unit with a front-mounted
plough basing on the theoretical investigation of the stability of its motion in the horizontal plane.
The methods of research include obtaining the amplitude- and phase-frequency response
characteristics of the dynamic system in order to analyse the stability of its motion under the
action of external statistically random perturbations. Also, the methods of software development
and PC-based numerical computation are applied. The results of the study prove that the increase
of the ploughing unit’s travel speed results in the considerable rise of the gain of the amplitude
of the tractor’s heading angle oscillation in response to the oscillation of the angular displacement
of the front-mounted plough in the horizontal plane. The phase-frequency response displays the
same behaviour, changing substantially together with the unit’s travel speed. Raising the
coefficient of resistance to tyre slip of the tractor’s rear wheels from 100 to 130 kPa and the front
wheels from 140 to 175 kPa results in a minor decrease of the amplitude of oscillation of the
tractor’s heading angle φ. The ploughing unit has the best response to the input effect, i.e. the
oscillation of the front-mounted plough’s angular displacement βp, when it operates using the
1+5 combination. The increase of the number of front-mounted plough bodies from 1 to 3 results
in the substantial growth of the tractor’s heading angle oscillation amplitude. Taking into account
the way, in which the ploughing unit as a dynamic system responds to the input perturbance, the
increase of its travel speed can be restricted not by the condition of its motion stability, but solely
by the agrotechnical requirements applied to such a process operation as ploughing. The
ploughing unit’s motion stability substantially improves in case of higher air pressure in the tyres
on the tractor’s front and rear wheels. This effect is especially pronounced in the perturbance
oscillation frequency range (0...1.5 s
–1
) that covers the main part of its dispersion.
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Article
Märksõnad
tractor, plough, push–pull, dynamic system, stability of motion, articles