If the machine to be aggregated has been selected, it is only necessary to determine the
operating speed and respective gear.
The operating speed of the tractors during the operation under field conditions is limited
first of all by the quality of the work to be performed. Besides, for traction machines it is lim-
ited by the tractive and hitching capabilities of the tractor and for traction and driven aggre-
gates – by the allowable power of the PTO and hydraulic takeoff as well as by the through-
put capacities of the machine tools.
Checking the correctness of formation of the aggregate according to the rotational
speed of the engine crankshaft. In practice, the operating motion speed of the tractor is
selected based on the tachospeedometer readings. While knowing the range of agroteche-
nically allowable speeds, the tractor gear (motion speed), in which the tractor shall enter this
range is determined.
The normal load on the tractor should be considered such a load, at which the readings
of the crankshaft rotational speed on the tachospeedometer would be lower (by not more
than 6%) than the rated value specified in the manufacturer’s documentation. Drop of the
rotational speed by the value exceeding 6% indicates the engine overloading. The increase
of the rotational speed above the rated one indicates the engine underloading.
The main condition of the optimal aggregation of the MTZ tractor is proper use of the en-
gine power which is characterized by the load factor expressing the degree of use of the
tractor’s rated power for performing the jobs by the aggregated agricultural machines. For
each group of agricultural operations exist objectively the approximate values of the degree
of use of the engine’s rated power.
The correctly selected operating mode of the tractor is understood as such aggregation of
the tractor with observing all the operating rules and limitations, which ensure not only per-
formance of the work in accordance with the agrotechnical requirements for the working op-
eration to be performed, such as engine loading mode, speed mode of the aggregate, al-
lowable skidding mode as well as compliance with all the recommendations for safe use of
the tractor (speed selection, loading modes).
The engine loading degree can be varied by increasing or reducing the number of ma-
chines, varying the grasp width, operating depth as well as motion speed in the process of
the operating motion of the aggregate. If the efficient loading of the engine by varying the
number of machines and operating speed is impossible, the respective partial operating
mode should be chosen by reducing the fuel feed.
The engine loading degree is determined from the crankshaft rotational speed. It is nec-
essary to work at the crankshaft rotational speed exceeding slightly the rated value (indicat-
ed on the tachospeedometer). If the operating speed is below the required value, a lower
gear shall be put in.
Allowable skidding mode. One of the main special requirements consists in observance
of the allowable skidding limits: 16% for wheeled tractors with two driving axles and up to
18% for wheeled tractors with one driving axle. The MTA shall be completed and the speed
mode shall be selected within the limits of allowable skidding. Excessive skidding of the trac-
tor propulsion devices causes the destruction of structural particles of the soil with subse-
quent development of the wind and water erosion.
4. Using the rear mounted attachment and hydraulic system
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