Practical Study for the Effect of Speed, Direction of Acceleration and Type of Machine on Vibrations Transferred to the Steering Wheel Horticulture Tractor Type (Goldoni)

Field an experiment was carried out in the farms of Agriculture and forestry academy at University in Nineveh. The research was conducted to investigate a practical study for the effect of four forward speeds (1.9, 2.6, 3.8 and 4.7 km/hr.) and three acceleration direction of axes lateral, longitudinal and vertical, and two types machines control (Mower and Rotovators) on the vibrations transferred to the steering wheel horticulture tractor type (Goldoni). The vibration points on the handgrip were calculated and tested. Root mean square acceleration (RMS), given in m/sec, was calculated. Results showed increased acceleration vibration of the three directions (longitudinal, lateral and vertical) transferred to the steering wheel tractor by increased forward speed. The Mower score recorded the highest acceleration vibration for the three directions of Rotovators. The levels of vibration emitted from tractor to hand an operator during the experiment was high comparing with standard mechanical vibration. Handgrip vibration intensity in the vertical direction is bigger than the lateral and longitudinal direction. The total vibration evaluating was denoted as the square root mean of the three sum value (lateral, longitudinal and vertical) directions. The paper purpose was measuring and analyzing vibration level transferred to the steering wheel and reduces the machine vibration. This paper is helpful for design in order to increase the develop safety systems in easy and economical way.


Introduction
Workers often suffer in heavy, especially those who are using. The equipment with the nature of the seismic events of significant health problems was encouraged to study and analyze and measure the vibration of workers in this area, which is one of the most interesting engineering applications. This physical factor that acts on the human body is vibration which transmits the mechanical energy from sources of oscillation [1]. Vibration can effect in different way to the operators; machine operators are always meeting two different types of vibration: vibrations effect to the whole-body produce through seat or floor and feet, and vibration which produced by the hand-grip. Both forms of vibration can effect on the operator which reduce on his job performance and health [2].
Farm tractors and other earth-moving equipment contribute to some of the most common, prolonged, and severe occupational exposures of vehicle vibration among equipment operators [3]. Disturbances in finger blood flow, and in neurological and motor functions of the hand and arm can produce by excessive exposure to hand-transmitted vibration. It has been estimated that 1.7% -3.6% of the American and European workers are exposed to potentially harmful hand transmitted vibration [4]. The European list of recognized occupational diseases inserted these disorders [5]. The term "handarm vibration syndrome" (HAVS) is a case resulting with the exposure of machincal vibrating transmitted through hand and arm that affect in disorders vascular, neurologic, and musculoskeletal.
Although that are a very important issue and serious in many nation, small concern are paid to that. Nearly any user of agricultural tools is exposed to "whole body vibration "or" hand arm vibration". Even people on work that seems simple careers such as cutting the grass in the garden by the machine or driving the tractor in the orchards can be exposed to sudden vibration; especially vibration resulted from the handle to the driver's hands. This vibration was known as a trouble [6]. Vibration in tractor depends on many factors velocity of tractor, topography of field, tractor condition and design tractor and configuration which is by dynamic response [7]. Vibration power resulting to use a lot of different types of agriculture's tools can cause hand vibration in the tractor driver, and used density of these tools can affect the nervous system such as changes in tendons, tissue diseases, muscles, bones and the vascular injury which also results lower blood flow that is the most common complication of this type of vibration which can produce white fingers [8]. The vibration entering to the operator hand not only causes health problems, but also lowers the driver working skills and sensation; using this type of tractors is very common in small and medium orchards and vegetable farms; these tractors considered easy to use and the cheapness, and these types known as small size tractor or single-axle tractor can be used in many agricultural operations like harvesting, plant protection, irrigation, threshing, and transportation [9]. Human exposure to mechanical vibration may represent a significant risk factor for exposed workers in the agricultural sector, with particular reference to the operators driving tractors [10].

Material and Methods
A field experiment was conducted at experimental field of agriculture and Forestry College at the University of Mosul in the north west of the city of Mosul.

Tasted Tractor
The implementation of the horticulture Goldoni tractor search type is shown in Table 1.
Used two types control machines (Mower) width work 120 cm and (Rotovators) width work 85 cm as shown in (Figure 1).

Soil
Soil type was clay-silt as shown in (Table 2).

The Experiment
Used vibration meter type (Adash4900-vabrio M) to measure the vibration force  The quantity used to describe the magnitude of vibration shall be the frequency weighted acceleration in meters per second squared (m/s 2 ), expressed as a rootmean-square. As, it is important that for additional purposes frequency spectra must be acquire, the frequency weighted acceleration can get using ISO 5008: where: ɑ h.w frequency weighted acceleration in the direction i (i = x, y or z), ɑ wj is the acceleration acquired (m/sec 2 ) and W j is dimensionless weighting factor as given in (Figure 3) (Figure 4).
It is also important vibration measure location shall be as close together as possible that significantly affect the measured value.
In consensus with the indicated ISO standards, the three directions of an orthogonal coordinate system, in which the vibration accelerations should be accounted, were as follows: z-axis, x-axis and y-axis.
In accordance with ISO 5349 the assessment of vibration exposure depends on a quantity that combines all three axes. This is weighted acceleration sum or vibration total value it is defined as the root-mean-square of the three constituent values: where: T is the total daily duration of the exposure (sec), and T 0 is the reference duration of 8 h.
When total daily vibration exposure contains many process, with various vibration magnitudes, the daily vibration exposure, A (8 hours) shall be calculates using: ( ) where ɑ hvi is the vibration gross rate for i the process, n is number of single exposures, and T i is the period of i the process.  Table 3 and Table 4.

Results and Discussion
Note from Figure 5 and Figure  respectively. These results agree with [11] who found the vibration acceleration increase as the forward speeds of the tractor increases.
As indicated in Figure 7          As indicated in Table 5

Conclusions
• The velocity of the tractor had the strongest effect on the vibration transmitted from the steering wheel to the hands of the driver from all axis. • Hand-arm vibration intensity is greater in the vertical direction than the lateral and longitudinal direction. • Like these value acceleration (rms) effects on driver and caused discomfort, will produce finger blanching, tired, and less performance and not completely control operation to the tractor by driver, and also appear the type of machine influence on the vibration.