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 231-3467vonrymonlipinski@kan.de www.kan.de

Dr. André KlußmannInstitute of Occupational Health, Safety and Ergonomics (ASER)Tel.: +49 202 731000a.klussmann@institut-aser.de 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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