SUBSTANTIATION THE EFFICIENT WAGONS OF TRACTOR TRAIN IN TRANSPORTATION OF AGRICULTURAL CARGOES

ABSTRACT

The results of research on traction resistance of a tractor train consisting of an Axos 340 tractor and Joskin trailers, depending on number of trailers, the weight of cargo loaded on them, and movement velocity are specified in the article.

АННОТАЦИЯ

В статье приведены результаты исследования тягового сопротивления тракторного поезда, состоящего из трактора Axos 340 и прицепов Joskin, в зависимости от количества прицепов, массы загружаемого на них груза и скорости движения.

Keywords: tractor train, cargo, slope angle of road, coefficient of resistance to rolling, resistance force, velocity, traction force on the hitch.

Ключевые слова: тракторный поезд, груз, угол наклона дороги, коэффициент сопротивления качению, сила сопротивления, скорость, сила тяги на крюке.

Introduction

It is known that main function of the tractor train is to transport goods from one destination to another in a short period of time and at low cost. 40-50 percent of expenses for agriculture is the share of vehicles, including tractor trains [1, 2, 3].     In last years, there was possibility increase the gross agricultural products in the republic by 6.6%. As a result, about 3 mln. tons of raw cotton, 8.3 mln. tons of wheat, more than 21 mln. tons of fruits and vegetables, including 3 mln. tons of potatoes, 11.3 mln. tons of fruits, 2 mln. tons of cucurbits, 1.7 mln. more than tons of grapes, 3 mln. tons of fruits and berries were grown and harvested. These cultivated areas contains 3.298 mln. hectares. Considering that 12 transport tractors correspond to every 1000 ha of land according to established standards, at least 39.600 units of transport tractors and 79.200 units of tractor trailers are required to transport the cultivated agricultural products and other goods [1].

In previous years, 2PTS-4-793 trailers with a load capacity of 4 tons were used on tractors of the 0.9 and 1.4 classes in agriculture, but now two-axle TTZ-8525 and Joskin trailers with load capacity of 6 and 8 tons are being manufactured by series fabrication, and they are the following: TTZ-100K10, MTZ -82 and modern 1.4 and 2.0 class Belarus 80.1, Belarus 82.1, Belarus 1221, Axos 340 having capacity 80-120 hp. (horse power) is being aggregated into tractors [3, 4].

Therefore, in order to effectively using the load-carrying capacity of trailers and power of transport tractors, it is advisable to widely use modern tractors and tractor trains consisting of two-axle trailers with cargo load capacity of 8 tons. Traction resistance of tractor train increases with the number of trailers, the weight of cargo loaded on them, and movement velocity [1, 3]. It is possible to increase the efficiency of agricultural transport by justifying the efficient wagons of tractor trains consisting of tractors and trailers.

Increasing the efficiency of tractor trains with a large carrying capacity and efficient wagons is a matter of scientific and practical importance.

Materials and research methods

Studies in effort to substantiate the traction force of tractor hitch and efficient trailers of train wagons were implemented.

Let’s use the following formula to determine value of force of the tractor hitch  in researching the efficient wagons of tractor train by aggregating the Joskin trailer with a load capacity of 8 tons to the currently widely used modern tractor Axos 340 (4K4) [2, 3, 4, 5, 6, 7]:

,                                     (1)

in this case – trailer mass, kg; – accelaration run of free fall ( m/s²);
 – slope angle of supporting level land, °; – accelaration run of trailer, m/s²;
 – resistance to movement of the tractor train, N.

Let’s consider movement velocity of the tractor trains as  for calculations (movement velocity of trailers is stable). Thus, acceleration run  inertia force   (in this case – resistance coefficient of wheel rolling, – weight of trailer, N).

In that event

                                      (2)

Number of trailers formula (2) for  is in place.

In the event if number of trailers is :

In the event if number of trailers is :

In the event if number of trailers is :

                                     (3)

Out of (3) the formula for determination the number will be formulated [1, 8]:

                                        (4)

Values of  will be calculated as in the following. For two-wheel drive 4K2 formula tractors [5, 9, 10, 11, 12] having operating mass greater than 2600 kg:

, (N).          (5)

in this case – operational weight of tractor, N; – design mass of tractor, kg;

For tractors of 4K4 formula having operating mass of more than 2600 kg, driving four wheels [1, 9, 10]:

(N).                   (6)

in this case  and – design and operational masses of tractor, kg.

Using the formulas given above, calculation the values of force at the tractor hitch and number of trailers at tractor train will be available. In road-soil conditions of Uzbekistan, 70% of the roads from cotton farms to reception points are paved with asphalt, and 30% are hard ground roads within farm, and in researching the efficient wagons of the tractor trains, it is recommended to accept the slope angle of the base plane determines the value of the rolling resistance coefficient of the wheels for ground pavement  and for asphalt pavement  [10].

1-option    Design mass of the tractor is  kg, operational mass is kg, due to that kg>2600kg let’s determine  value by means of formula (6):

 kN.

From (4):

2-option:    In this case  kN, kN and  remains as it (unchanged). From (4):

3-option:    From (4):

From obtained figures one can see, that the number  of trailers containing at tractor train increases with increasing values of the force  at tractor hitch, while the weight  of single trailer remains unchanged, and on contrary, it decreases with increasing values of slope angle of the supporting level land and coefficient of rolling resistance  of wheels.

Weight of a single trailer increases with increasing values of force on the tractor hitches while remaining unchanged, but decreases with increasing values of the slope angle of the support plane and the coefficient of rolling resistance of the wheels.

Values of traction resistance of trains consisting of AXOS 340 tractor and Joskin trailers and those trailers aggregated to it are shown in tables and graphs.

Research results

Experimental studies were carried out on tractor trains consisting of AXOS 340 tractor and Joskin trailers with assembly of the load capacity of 8 tons in accordance with requirements of the state standards for testing practice [1, 8, 10, 11]. Trials were carried out separately in transmission of each velocity of the tractor on road having length of 3000 m. Cargo (cotton) was loaded onto trailers after each run and arrival of tractor train. In this way, values of traction resistance were increased. Each trial was carried out in sequence of forward movements of the train with the same loading.

Values of traction resistance of trains consisting of AXOS 340 tractor and Joskin trailers and trailers aggregated to it are shown in table.

Table 1.

Values of traction force at hitch of train consisting of AXOS 340 tractor and Joskin trailers with assembly of load capacity of 8 tons (design mass of each trailer is 24.3 kN)

Discussion of results

From results of the study, one can seen that AXOS 340 tractor of 1.4-class with 75 kW (102 h.p.) and load capacity of assembled to it was 8 tons; 2 out of Joskin trailers (design mass of each trailer is 24.3 kN) when moving on the flat road (total trailer load capacity 12 tons) only 13 percent of tractor's pulling force is used [1, 10, 11].

Tractors with 75 kW (102 h.p.) can pull 6 trailers with a load capacity of 8 tons (total loading 48 tons) when moving on flat road.

In comparing with acting 2PTS-4-793A trailer with the 4-tons capacity, transportation expenditures are reduced to 47 percent by using 8-ton Joskin trailer.

Summary

Traction resistance of tractor train increases by increasing the number of trailers, weight of cargo loaded on them and the velocity of movement.

Traction resistance of tractor train consisting of an Axos 340 tractor and Joskin trailers increases with the number of trailers as the load weight loaded to them and movement velocity rises up. In Axos 340 tractor and 2 units of Joskin tractor train, the utilization rate of maximum traction force on tractor hitch is 7%.

When the movement velocity of the train reaches 35 km/h the value of traction force at hitch will be  N and it can pull 6 trailers.

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