buletinul institutului politehnic din iaşi - Universitatea Tehnică ...

256 Iona Ţenu et al.
parts and wheels’ working parameters leading to soil degradation and
compaction. In this context, correlations must be established between the
wheels’ working parameters, soil compaction and the degradation level
(Căproiu et al.,1973; Drăgan,1969; Neculăiasa,1971; Şandru et al.,1983), as
well as the evaluation of the impact of the active parts on soil physical
degradation indices.
In order to solve the above-mentioned problems, a laboratory rig with soil
bin was built in order to study the interaction of the active parts and wheels with
the ground.
2. Material and Method
The test rig (Fig. 1) consists of the frame of the soil bin (1), the soil bin
(2) and the carriage (3), on which the tillage active part (6), the tyre wheel (7)
and the compacting roller (8) are mounted; and at the end of the soil bin frame
an electric cable drum is attached, in order to tow the carriage by the means of
the cable (5).
The electric cable drum consists of an electric motor (9), a cylindrical
gear drive and a drum (10); the latter one operates the cable (5), which is towing
the carriage (3). The towing cable ends (5) are connected to the carriage frame
by the means of two strain gauge load cells (4), allowing the measurement of
the traction force needed to displace the carriage or to drive the tyre wheel.
An electric motor (12) is mounted on the carriage and also a cylindrical
gear for driving the tyre wheel (7). The lifting screw mechanisms (13) are used
in order to adjust the working depth of the active part (6). The screw
mechanism (14) allows the adjustment of the wheel’s vertical position; the
vertical position of the compacting roller is adjusted by means of the screw
mechanism (15).
The carriage levelling-compacting roller (8) is used in order to achieve a
certain level of soil compaction before the operation of the tillage active part or
before testing the tyre wheel.
When the carriage is towed by the means of the cable and the electric
motor (9), the tyre wheel (7) has a free rotation movement due to its interaction
with the soil and allows the modelling of the wheel-ground interaction process
for a driven tractor wheel. When the carriage is not towed by the means of the
cable, movement is achieved due to the tyre wheel (7), which is driving the
carraige: the wheel is driven by electric motor (12) through a cylindrical gear
and a trapezoidal belt drive. This latter situation allows modelling the wheelground
interaction for tractor driving wheels.
The force measuring system positioned in the front of the carriage is used
to measure the resistance force developed by the active part at the interaction
interface of the agricultural equipment active part-ground. The force
measuring system located at the rear of the carriage allows the measurement of
the driving force developed by the driving tyre wheel.