Nativa, Sinop, v. 9, n. 4, p. 413-418, 2021.
Pesquisas Agrárias e Ambientais
DOI: https://doi.org/10.31413/nativa.v9i4.12493 ISSN: 2318-7670
Noise levels emitted by agricultural tractors with and without
implements activation
Amanda Pereira Assis GOMES1, Gabriel Araújo e Silva FERRAZ2, Diego Bedin MARIN2*,
Fabiano Battemarco da SILVA3, Luana Mendes dos SANTOS2, Patrícia Ferreira Ponciano FERRAZ2
1Federal University of Viçosa, Viçosa, MG, Brazil.
2Federal University of Lavras, Lavras, MG, Brazil.
3Federal Rural University of Rio de Janeiro, Seropédica, RJ, Brazil.
*E-mail: db.marin@hotmail.com
(ORCID: 0000-0002-8912-2690; 0000-0001-6403-2210; 0000-0001-7526-0825; 0000-0002-0623-6941;
0000-0001-8406-2820; 0000-0002-9708-0259)
Recebido em 30/05/2021; Aceito em 10/09/2021; Publicado em 23/09/2021.
ABSTRACT: The noise levels emitted by agricultural machines can be harmful to the worker's health, and it
is sometimes neglected in rural areas. This work aimed to measure the noise level emitted by three agricultural
tractors of different power activating two types of implements to assess whether there were risks to operators'
health and the supporter workers around the tractor. The noise level data were collected using a decibel meter
in ten points on each machine side (forward, rear, left, and right) for a total of 40 points around each tractor.
Three different tractors were evaluated in different scenarios: without any implement, coupling and activating
a spreader, and coupling and activating a rotary hoe. The tractor was parked at the centre of the mash with an
engine speed that ensured 540 rotation per minute (RPM). to the power take-off (PTO) during the entire data
collection. The data were analyzed by charts, linear regression, and hierarchical clustering analysis. The results
indicated that the sound pressure levels in all of the studied situation exceed the standard's limits regulatory
standard 15, making hearing protectors essential during the working day.
Keywords: ergonomics; acoustic comfort; agricultural mechanization; sound pressure level.
Níveis de ruído emitidos por tratores agrícolas com e sem acionamento de
implementos
RESUMO: Os níveis de ruído emitidos pelas máquinas agrícolas podem ser prejudiciais à saúde do trabalhador
e, por vezes, negligenciados no meio rural. Este trabalho teve como objetivo mensurar os níveis de ruído
emitidos por três tratores agrícolas de diferentes potências acionando dois tipos de implementos para avaliar se
havia riscos à saúde dos operadores e trabalhadores de apoio ao redor da operação. Os dados de ruído foram
coletados por decibelímetro em dez pontos de cada lado da máquina (frente, trás, esquerda e direita) para um
total de 40 pontos ao redor de cada trator. Três tratores diferentes foram avaliados em diferentes cenários: sem
implemento, acoplando e acionando uma esparramadora de corretivo e acoplando e acionando uma enxada
giratória. O trator foi estacionado no centro da mistura com uma rotação do motor que garantiu 540 rotações
por minuto (RPM). para a tomada de potência (TDP) durante toda a coleta de dados. Os dados foram analisados
por meio de gráficos, regressão linear e análise de agrupamento hierárquico. Os resultados indicaram que os
níveis de pressão sonora em todas as situações estudadas ultrapassam os limites da norma regulamentadora
(NR) 15, tornando os protetores auditivos indispensáveis durante a jornada de trabalho.
Palavras-chave: ergonomia; conforto acústico; mecanização agrícola; nível de pressão sonora.
1. INTRODUCTION
Rural areas are facing significant social, economic,
demographic, and environmental challenges (BAMBI et al.,
2019). One of these challenges could be highlighted is the
mechanization of the rural operations. The technological
development of the agricultural machinery not only
promotes the increase of agricultural production but also
seeks improvements in the development of activities and the
reduction of time losses during the operations (VIAN et al.,
2013). Parallel to the development of technology, the use of
mechanization processes of agricultural production has
brought about the factors such as noise, vibration, exhaust,
etc., which affect the working environment of users of those
machines (AYBEK et al., 2010).
Agriculture is among the risky industries accompanied by
different process and tasks where each task has the capability
for any kind of risks and harmful effects on farmers
(GHOTBI et al., 2013). Extreme temperature, noise,
mechanical vibration injuries, dust, ultraviolet, and pesticides
are among the harmful effects that farmers are faced with
(KUMAR et al., 2005). Currently, attention has been focused
on the workers' well-being during the labor activities,
focusing mainly on their safety and comfort (YANAGI
JUNIOR et al., 2012). Workers' comfort is directly related to
their performance and efficiency in performing their
activities (BRAVALHERI et al., 2010).
Noise levels emitted by agricultural tractors with and without implements activation
Nativa, Sinop, v. 9, n. 4, p. 413-418, 2021.
414
According to the Brazilian regulatory NR-15
(Occupational Safety and Health Regulatory Standard, 1990)
the noise levels should not exceed 85 dB (A), during the eight
hours workday, to ensure healthy conditions for workers.
This standard also states that levels above 115 dB (A) without
proper protection expose a severe risk to human health.
The study of noise emission by agricultural machines, as
well as its effects, mitigation ways, and prevention, are very
relevant, as they can contribute to the comfort and well-being
of rural workers, and consequently to their health and better
performance. Hence, it is essential to know the conformity
to the level noise of tractors and agricultural implements.
Compare the noise emitted by tractors that are activating
different implements is significant to understand. Thus, this
work aimed to measure the noise levels emitted by three
agricultural tractors with different power and activate
different agricultural implements to assess the operator's
health risk and the supporter workers around the tractor.
2. MATERIAL AND METHODS
The experiment was carried out in Lavras, Minas Gerais
State, Brazil, in an open area of the Engineering Department
(DEG) of the Federal University of Lavras (UFLA). The area
consists of asphalt pavement without the presence of
surrounding buildings, measuring 50 x 60 m. It is located
between the coordinates 21°13'50.74” S and 44°58'30.86” W
of Greenwich.
Three tractors were tested in this experiment. They have
no cabin protection and had different levels of nominal
powers. They were tested in three scenarios: (1) without the
coupling of implements; (2) coupling and activating a
spreader; and (3) coupling and activating a rotary hoe. Table
1 presents the tractors and the implements used in this
experiment, as well as their main features.
Tabel 1. Technical specifications of agricultural machines and implements used in the experiment.
Tabela 1. Especificações técnicas das máquinas e implementos agrícolas utilizados no experimento.
Tractors
Nominal power (kW)
Rated engine speed (rpm)*
Manufacture year
Tractor A
80
.
90
1920
2007
Tractor B
69.87
1890
1996
Tractor C
60.31
1700
1986
Implements
Brand and Model
Rotary Hoe (R)
Lavrale RSFE 50, with a working width of 1.6m e working depth of 0.25m
Spreader (S)
Maschietto CA 2600
27011
*to ensure 540 rpm at PTO
Noise levels were determined using the sound level
meter, Instruterm DEC – 480, in the slow response circuit
and "A" equalization, expressed in dB. The windshield of this
meter was used for all measurements. The noise level
evaluations were performed according to the methodology
described in NBR 9999 (ABNT, 1987), in which the ambient
temperature should be between -5 and 30 ºC, and the air
velocity should be less than 5.0 m s-1. So, the trials were
performed in the early morning (07:00 a.m) and late
afternoon (04:00 p.m), at a temperature of approximately 25
°C, according to the Lavras meteorological station.
The data collection was performed at the average height
of the operator's ear. According to Kroemer and Grandjean
(2005), the average height of a standing man is 1.70 m, from
the floor. At the operator's seat, it was collecting the noise at
0.9 m from the tractor floor, which corresponds to a seated
operator's height in the working position on the tractor
(KROEMER; GRANDJEAN, 2005).
The data were collected at points placed every two meters
on the right, left, forward, and rear sides and at the operator
seat (41 sampling points) (Figure 1) from the agricultural
machine. The center point (0, 0) corresponded to the place
where the tractor remained parked and in rated engine speed
that ensures 540 RPM. to the power take-off (PTO) during
the entire collection. Also, the point (0,0) corresponds to the
operator seat.
The values described by the Brazilian standard NR-15 of
the Ministry of Labor and Employment (Table 2) were used
to identify the worker discomfort according to the noise
level.
Figure 1. Diagram of noise level sampling points.
Figura 1. Diagrama de pontos de amostragem do nível de ruído.
Table 2. Tolerance limits for continuous or intermittent noise (NR-
15).
Tabela 2. Limites de tolerância para ruído contínuo ou intermitente
(NR-15).
Noise level dB (A)
Maximum allowable daily
exposure
85 8 hours
86 7 hours
87 6 hours
88 5 hours
90 4 hours
95 2 hours
100 1 hour
105 30 minutes
110 15 minutes
115 7 minutes
Gomes et al.
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415
A descriptive analysis was used to describe the noise level
emitted by the tractor in three scenarios and on each side of
the machine. In addition to this, the hierarchical clustering
analysis has been made using the R statistical software was
proceeded to identify similarity among the three tractors'
situations, and the side of the noise level sampling.
The hierarchical agglomerative clustering analyses (HCA)
was used to separate objects into groups based on
characteristics of the objects. The basic idea is to put in the
same group objects that are similar according to some
predetermined criterion (LINDEN, 2009). The HCA was
proceeded according to Lau et al. (2009) and Ferraz et al.
(2014). The cluster heat map described the results of this
analysis.
According to Wilkinson; Friendly (2009), the cluster
heatmaps visualize a hierarchically clustered data matrix using
a reordered heatmap with dendrograms in the margin.
According to Yu et al. (2020) the heatmap, a graphical
representation of data with the individual values contained in
a matrix, was represented as grids of colors plus clustering on
both rows and columns. So, these analyses make it possible
to compare the noise level emitted by the rural machinery
tested by this study in different situations.
3. RESULTS AND DISCUSSION
According to NR15, the sound level 85 dB(A) is the
maximum allowed for a daily exposure of eight hours, which
corresponds to the daily working hours of a tractor operator,
without the obligation to use the ear protector device.
However, the maximum values observed during the
experiment points to a maximum daily exposure of
approximately two hours. So, it requires the use of the ear
protector device to protect the operator during the operation.
It is possible to observe in Figure 2 that the highest noise
level measured at the tractor forward was at two meters from
the worker seat for all of the studied scenarios. It was
expected since it is closer to the tractor engine. Noise levels
decreased as the distance between the engine and the
measured point increased. Tractor C presented the minor
critical distance for the workers' health at the tractors
forward. This distance was 3 m without implement and also
when it was activating the rotary hoe, and approximately 5m
when it was activating the spreader. Tractor B presented a
critical distance higher than Tractor C. It is possible to
observe that this critical distance can be 6 m.
Furthermore, it was possible to observe that the noise
level emitted at the front of Tractor B had similar values to
all investigated scenarios. The tractor C, coupled with a rotary
hoe, emitted higher levels at the front than the spreader.
Analyzing Tractor A, even with the activation of implements,
the noise levels did not present significant variations.
The small noise levels variation measured at the tractor
forward among the scenarios of activated implements or
without implement occurred because the implements were
coupled at the backside of the tractor. Therefore, the noise
emitted was directed towards the tractor rear (Fig. 3), and it
did not affect the forward measurements.
All of the investigated tractors presented higher levels of
noise at the rear in all scenarios, which caused an increase of
the critical distance to the worker's presence. Thus, the
implement contributed to the increase of noise levels at the
rear. Even with tractors operating with the spreader and
rotary hoe, the highest noise levels were found at the front of
the tractor, because the engine operation makes a high noise
level, but the coupling of the implements increased the noise
level emitted by the set at the rear.
The safe distance without ear protection observed at the
rear of the tractor was 4 m for Tractor A, 6 m for Tractor B,
and 4 m for Tractor C, all of them occurred when they were
activating the spreader.
Figure 2. Values of the noise levels measured at the tractor A, B, and
C forward (F) at the three studied situations: without implement (0),
with spreader (S) and with a rotary hoe (R).
Figura 2. Valores dos níveis de ruído medidos na frente dos tratores
A, B e C nas três situações estudadas: sem implemento (0), com
esparramadora (S) e com uma enxada rotativa (R).
Figure 3. Values of the noise levels measured at the rear (Re) A, B,
and C of the tractors at the three studied situations: without
implement (0), with spreader (S) and with a rotary hoe (R).
Figure 2. Valores dos níveis de ruído medidos na traseira (Re) A, B
e C dos tratores nas três situações estudadas: sem implemento (0),
com esparramadora (S) e com uma enxada rotativa (R).
Figure 4. Values of noise levels measured on the right side (Ri) of
tractors A, B and C in the three situations studied: without
implement (0), with spreader (S) and with a rotary hoe (R).
Figure 2. Valores dos níveis de ruído medidos no lado direito (Ri)
dos tratores A, B e C nas três situações estudadas: sem implemento
(0), com esparramadora (S) e com uma enxada rotativa (R).
Noise levels emitted by agricultural tractors with and without implements activation
Nativa, Sinop, v. 9, n. 4, p. 413-418, 2021.
416
Through the analysis of Fig. 4 and Fig. 5, it is possible to
observe how the noise levels behave on the left and right
sides, respectively, for tractors A, B, and C with and without
the activation of implements.
Figure 5. Values of the noise levels measured at the tractor A, B, and
C left (L) side at the three studied situations: without implement (0),
with spreader (S) and with a rotary hoe (R).
Figure 2. Valores dos níveis de ruído medidos no lado esquerdo (L)
dos tratores A, B e C nas três situações estudadas: sem implemento
(0), com esparramadora (S) e com uma enxada rotativa (R).
4. DISCUSSION
The observed critical distance to avoid the use of hearing
protection devices at the right side was 4 m for Tractor A, 5
m for Tractor B, and 2 m for Tractor C. For the left side of
the tractors the critical distance was observed at 4 m and 3
m, respectively, for A, B, and C.
Although the noise levels observed on both sides seem
similar, the right side showed slightly higher levels than the
left side, which were caused by some engine components
located on the right side of the tractor's front. Baesso et al.
(2017), studying noise levels observed in several distance
points from comparable tractors of those investigated, found
similar values in the right and left sides, which corroborates
to the results found by this work.
On the right and left sides, it was highlighted that the
critical distance becomes smaller than the front and rear of
the tractor. It was also possible to notice that in the operator's
seat, the noise levels found for the three tractors, with and
without the activation of implements, was higher than 85dB
(A), which makes it obligatory the use of hearing protector
for both operator and assistants which were working within
6 m or less of the tractors tested.
Hierarchical clustering analysis was developed to make a
comparison of all studied scenarios, using average values
(Figure 6). This analysis is used to separate objects into
groups based on the characteristics of the objects (Ferraz et
al., 2014). According to Linden (2009), the basic idea is to put
in the same group objects that are similar according to some
predetermined criterion. So, Figure 6 represents the cluster
heatmap with HCA related to the similarity noise values of
the tractors in the forward, rear, right, and left side, with and
without the activation of implements.
The result showed that tractor C with spreader (C-s) was
grouped with A – 0 and A- s. They ware similar to all studied
side (Figure 6). Similar behaviour was found by Bilski (2013).
Thus, it was noteworthy that newer tractors have a lower
noise emission due to studies and advances in the field of
ergonomics (BILSKI, 2013; LJUNGBERG; NEELY, 2007;
LJUNGBERG et al., 2004).
Tractor B, even without the activation of implements, has
registered the highest noise levels as it is possible to observe
by the red colours in Figure 6. Also, it has been clustered
separately from other tractors. These results reinforced that
technology development was carried about the noise
emissions and consequently about the workers' health.
Tractor A was manufactured 11 years after the tractor B and
presented 11 kW more power than tractor B, and Tractor B
presented the highest level of noise values.
According to Cunha et al. (2012), tractors with higher
horsepower emit higher noise levels. However, technological
advancement allows for better machine quality in terms of
ergonomics, improving operator health, comfort, and
efficiency (Cunha et al., 2012). Tractor A is 11 years newer
than tractor B. This fact may explain why tractor B presented
a higher noise level than A, even it is of lower power than
tractor A.
Between the studied implements, the spreader presented
higher noise levels than the rotary hoe, which means that this
implement requires more caution when related to noise
emissions. Regarding to the machine side, the left and right
were grouped (Figure 6), while the front side and rear were
group into two other different groups.
Figure 6. Dendrogram of the noise levels observed at the forward,
rear, right and left side of tractors A, B, and C to the three studied
situations.
Figure 2. Dendrograma dos níveis de ruído observados à frente,
atrás, lado direito e esquerdo dos tratores A, B e C para as três
situações estudadas.
5. CONCLUSION
The activation of a rotary hoe and also the spreader
activation increase the noise emitted by the studied tractors.
The tractor C presented similar noise emission values to
Tractor A. Tractor B presented the highest noise emissions
values for all studied situations.
It was observed that in all studied scenarios, the operator
was subjected to high noise levels, above the 85 dB (A) limit
for 8 hours of daily exposure, without an ear protector. It was
also highlighted that the activation of the rotary hoe and the
spreader contributed to the increase of noise levels observed,
especially at the tractor rear. The safer distance from the
Gomes et al.
Nativa, Sinop, v. 9, n. 4, p. 413-418, 2021.
417
tractor in all studied scenarios was 5 m for tractor A and C
and 6 m for Tractor B.
6. ACKNOWLEDGEMENTS
The authors thank the Coordination for Improvement of
Higher Education Personnel (CAPES), the National Council
for Scientific and Technological Development (CNPq) and
the Foundation for Research Support of the State of Minas
Gerais (FAPEMIG) and the Federal University of Lavras
(UFLA).
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