NOTE 1 ISO 16840‑4 provides test methods and requirements for some PSDs when used as part of a wheelchair seat in a motor vehicle.

NOTE 2 Performance criteria have been established in some of the defined tests. In others, no minimum requirements are currently specified.

NOTE 3 For masses greater than 150 kg or less than 25 kg, appropriate extrapolation of test apparatus dimensions, mounting point separation, etc. are permitted.

NOTE 4 Rigid surrogate test fixtures are utilized to provide a worst-case situation, and consequently this part of ISO 16840 does not test a PSD on a particular wheelchair.

NOTE 5 If one PSD achieves a higher loading at the point of failure than another, it does not necessarily mean that it is better or worse. The type of failure and flexibility of the PSD can be considered as well. The maximum offset distance to the centre of the PSD from the adjacent attachment point can also be considered.