operating forces on agricultural machinery analysis and measurement of manual operating forces...
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Operating forces on agricultural machinery
Analysis and measurement of manual operating forces
International Conference “Women’s health and work”
Katharina von Rymon Lipinski (KAN) and André Klußmann (ASER) Brussels, 2015-03-05
Who is KAN?
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KAN is the Commission for Occupational Health and Safety and Standardization (in Germany)
KAN itself is not a standardization body, however!
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Presenting: KAN
Tasks• monitor standardization work from the OSH perspective
and to ensure OSH interests are reflected in standardization.
• “pools” the opinions of OSH stakeholders(based on a broad consensus betweenall parties) and supplies the resulting position as input, in the form of comments,on current and planned standardization projects or existing standards
Not enough knowledge? KAN study
How we can support you
• We formulate consensus-based OSH-positions on key standardization issues
• We asses standards to determine if they meet OSH requirements (from the German point of view)
• We exert influence on standardization programmes and mandates
• We initiate new standards if necessary from the OSH point of view
• We distribute information on standardization work for OSH experts
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Why a KAN study on actuating forces?
KAN study on agricultural machinery 2008:• standards were checked if they fullfil the essential
health and safety requirements of the Machinery Directive
National process of revision of standards
But: one problem left
How to deal with actuating forces on agricultural machinery?
And how to verify data given in standards on a certain machine?
Operating forces on agricultural machineryAnalysis and measurement of manual operating forces
Background• In the standards for agricultural machinery, two basic
statements often made according to operating forces:• During actuation of controls (e.g. levers) or moving of
components of machines (e.g. large flaps), • an average value of 250 N (200 N) and • a maximum value of 400 N (250 N)
must not be exceeded!
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Are the values suitable?
How to measure the force?
Examples of operation forces
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Location of operating elements …
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DIN 33402, part 2
e.g. females, 5. Percentile
upwards: 1840 mm
forwards: 625 mm
Operating forces on agricultural machineryAnalysis and measurement of manual operating forces
Aims• To develop a well practicable measuring procedure
for the determination of operating forces at machines.• To check whether maximum acceptable operating
forces (400 N peak and 250 N mean force) often mentioned in ISO standards for mobile agricultural machinery are arguable from an ergonomic point of view.
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Gender aspect: Not (only) men‘s work! Today, more than ¼ of trainees in agricultural occupations in
Germany are females (www.rlv.de)
Operating forces on agricultural machineryAnalysis and measurement of manual operating forces
Methods• Development and testing of
• a manual procedure and • an automatic procedure
for the determination of operating forces • Reference values:
Measurement of maximum isometric body strength in typical postures during operating machinery
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Manual measurement procedure
• Measurement with hand held force gauge
• Movement by examiners• Operating force to be angle
of 90°determined is perpendicular to the manually operated part (permanent)
• Every test was repeated several times
• Tests at machines in field and at test stand in laboratory
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Example of manual measurement of operating force
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Automatic measurement procedure
• Measurement with computer-aided measuring system
• Movement by Winch• Continuous angle
measurement• Every test was repeated 5
times • Tests at machines in field
and at test stand in laboratory
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Example of automatic measurement of operating force
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Comparison of the two measurement results
• Several tests have been done in the field at machines and in laboratory to compare the two methods
• Repeatability- and reproducibility-coefficient of variance (C.O.V.) over all measurements of operational force have been estimated
• manual procedure has a higher variance but the variance is not essentially higher compared to the
automatic procedure 2015-03-05International Conference "Women's health and work" 15
procedureAverage repeatability
C.O.V.Average reproducibility
C.O.V.
automatic 2,8 % 2,9 %
manual 4,4 % 6,6 %
Discussion of measurement results
• The automatic procedure predominates in reproducibility
• The manual procedure is easier to apply, still provides adequate, slightly higher results
• The manual procedure requires practiced examiners
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Recommendations:1) The manual procedure is sufficient to estimate the
operating force
2) Only the measurement of the maximum force is repeatable, the mean force is strongly dependent on
the speed of movement
Exemplarily determined maximum force values
• Measurements were done in standardized way in laboratory • 8 subjects (4 females, 4 males)• 3 cases (operating a lever, opening/closing side flaps
and locking a ladder) in 3 - 15 positions distributed over the human handling area
• 3,192 measurements with 133 combinations (direction / position)
Results:• 12 tables were generated in which orientation values
of isometric maximum forces for different body positions are shown.
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Tables
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Example table for maximum force of males (M) and females (W) in different spatial positions
Kind of force exercise here:
"Press the lever“
Summary / Discussion / Conclusions
Measurement / methods• Both procedures tested (manual and automatic)
have advantages and disadvantages. Tendency rather to manual hand-held force gauge
Maximum allowable levels for operating force• Previous values (250 N average, 400 N peak force)
not recommended• Significant differences between women and men
have to be taken into account • Significant differences in dependence of the spatial
position have to be taken into account• User population must be specified
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Summary / Discussion / Conclusions
Spatial position of controls / access• Location of control must be in reach of potential
users• Recommendation: Consideration of 5th percentile
females according to reach area (e.g. DIN 33402-2).
Use of the report • Method and reference values should be tested by
machine designers and construction engineers for applicability
• If useful, a larger database is necessary for reference values
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More details …
www.kan.de/publikationen/kan-studien/
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www.kan.de/en/publications/kan-studies/
ContactKatharina von Rymon LipinskiCommission for Occupational Health and Safety and Standardization (KAN) - SecretariatTel.: +49 2241 [email protected] www.kan.de
Dr. André KlußmannInstitute of Occupational Health, Safety and Ergonomics (ASER)Tel.: +49 202 [email protected] www.institut-aser.de
Picture credits
Slide „Contact“: © Trueffelpix - Fotolia.com
„Presenting: KAN“: © Vasilius - Fotolia.com
„Why a KAN study…?“: © mr.nico – Fotolia.com
„Who is KAN?“: © KAN
„How we can support you?“: © KAN
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