Example of ISO Standard Tests

February 9, 2011

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A Whirlwind II wheelchair, shown in the photograph, was built by a factory in Quang Ngai, Vietnam. It was first subjected to the tests described in “Simplified Strength Testing of Manual Wheelchairs in Developing Countries.” A few minor strength problems were identified and corrected. 

The chair was then submitted to the VA Pittsburgh Healthcare System – University of Pittsburgh’s Human Engineering Research Laboratory for testing in accordance with the ISO International Standards for Wheelchairs. 

The following test report shows that the chair passed all the Static Strength tests except that the force to pull the handgrips off the push handles was too low. It passed the fatigue tests, namely, the 200,000 cycle Two-drum test, and the 6,666 Curb Drop Test.


This indicates that the chairs that pass the “Simplified Standard Tests” have a good prospect of also passing the “ISO Wheelchair Standard Tests”. Human Engineeering Research Laboratory, University of Pittsburgh.

Human Engineering Research Laboratories
Wheelchair Standard Test Form
7180 Highland Drive
151R-1
Pittsburgh, PA 15206
(412) 365-4850

The following versions of the ISO Standards were used to perform tests on the following chair.

Name/Number: Whirlwind Wheelchair / produced in Viet Nam; Prototype
Chair Type: Manual

Contact: Dwight O. Johnson, MSME,
VIVCO Assistive Technology Services
e-mail: dwight at whirlwindwheelchair.org

ISO 01 (Static Stability) – ISO/CD 7176-1:1995-05-03 (E)
ISO 05 (Overall Dimensions) – ISO 7176-5:1986-03-01
ISO 07 (Seating Dimensions) – ISO 7176-7:Draft 1992-12-10
ISO 08 (Static, Impact, Fatigue) – ISO 7176-8:Draft 1996-05-09

The test values disclosed represent values based upon the testing of one wheelchair. These values represent the maximum performance without failure as tested on a new wheelchair. The performance that a wheelchair rider would obtain from a specific wheelchair may vary,depending upon environmental conditions and personal wheelchair riding habits.

Contact: Rory A. Cooper, Ph.D.
Director, Human Engineering Research Laboratories
Tel: (412) 365-4850

Acknowledgements 
Whirlwind Wheelchair International is grateful to the Human Engineering Research Laboratories at the University of Pittsburgh for conducting the tests as a donation toward development of high quality of wheelchairs that can be built in Developing countries. HERL can be contacted by e-mail at: by e-mail: rcooper+@pitt.edu or through its web site at Healthcare System – University of Pittsburgh’s HERL.

The chair did not have adjustments

Static Stability ISO/CD 7176-1

Stability Direction Most Stable Least Stable
Forward (Downhill) 24.4º na
Rear (Uphill) Wheels locked 5.8º na
Rear (Uphill) Wheels unlocked 11.7º na
Lateral 15.0º na

Determination of overall dimensions, Mass, and Turning Space ISO 7176-5

Stability Direction 1015mm
Forward (Downhill) 630mm
Rear (Uphill) Wheels locked 320mm
Rear (Uphill) Wheels unlocked 810mm
Largest component Dimensions: No quick release components
Volume .288 cubic meters
Total Mass 18.4kg

Seating and Wheel Dimensions ISO 7176-7

Seat Plane Angle 17.5º
Effective Seat Depth 470mm
Maximum Seat Width 400mm
Effective Seat Width 390mm
Seat Surface Height 460mm
Backrest Angle 17.9º
Backrest Height 380mm
Backrest Width 360mm
Seat to Footrest Height 420mm
Footrest Clearance 75mm
Footrest Length 120mm
Footrest Angle 21.0º
Leg to Seat Surface Angle 93.8º
Armrest Height 250mm
Front of Armrest to Backrest 370mm
Armrest Length 490mm
Armrest Width 20mm
Armrest Angle (Radius) 400mm
Distance Between Armrests 390mm
Front Location of Armrests 370mm
Hand Rim Diameter 450mm
Propelling Wheel Diameter 610mm
Horizontal Location of Wheel Axle 0
Vertical Location of Wheel Axle 110mm

 

Requirements for Static, Impact, and Fatigue Strengths ISO 7176

Static Strength

Static Strength Test Pass/Fail
760N Downward Force on Armrest Pass
1000N Outward Pull on Handgrips Fail
1000N Downward Force on Footrest Pass
1000N Downward Force on Tipping Lever na
440N Upward Force on Footrest Pass
1760N Up on Push Handles Pass

Impact Strength

Impact Strength Test Pass/Fail
Backrest Impact Pass
Handrim Impact Pass
Castor Impact Pass
Footrest Lateral Impact Pass
Footrest Longitudinal Impact Pass

Fatigue Strength

Fatigue Test Cycles Completed
Two – Drum Test 200,000
Two – Drop Test 6666


Comments Concerning Two-Drum Test: The chair sustained no significant damage during the two-drum test.

149,906/200,000 Cycles: Flat tire right side/repair restart
153,294/200,000 Cycles: Flat tire right side/repair restart
161,539/200,000 Cycles: Flat tire right side/repair restart
193,909/200,000 Cycles: Flat tire right side/repair restart 

6666/6666 Cycles: The chair sustained no significant damage during the curb drop test except for a bent rim caused by a flat tire.
34/6666 Cycles: Flat tire right side/repair restart
1134/6666 Cycles: Flat tire right side/repair restart: rim bent; replace and restart

General Comments:
The front caster wheel discs bent somewhat during testing, but did not adversly effect the performance of the chair.