TABLE 4.
Product testing matrix.
| Components | Failure modes | Test factors | Priority | ISO test methods |
|---|---|---|---|---|
| Castors, rear wheels and bearings | Tyre type, wheel and castor features and bearings affect rolling resistance | Rollability: effort required to propel wheelchairs on paved and unpaved surfaces | High | Not in ISO 7176 |
| Broken castor and wheel parts | Durability: impacts and loads; fracture loads | Yes (ISO 7176-8), but does not reproduce complex load conditions that occur in LREs | ||
| Worn out tyres | Durability: abrasion | Not in ISO 7176 | ||
| Parts degradation | Durability: accelerated ageing | Not in ISO 7176 | ||
| Corroded bearings and metallic parts | Durability: corrosion | Not in ISO 7176 | ||
| Fluttering castor may waste effort and cause accidents | Castor flutter | Seen on ISO 7176-8 multi-drum test but not tested for | ||
| Tyre puncture | Air retention for wheels, puncture tests | Not in ISO 7176 | ||
| Worn out bearings, dirt and dust in bearings | Test lubrication quality, seal design and quality | Not in ISO 7176 | ||
| Trueness of wheels over time is affected, camber issues | Wheel alignment | Not in ISO 7176 | ||
| Seat cushion and upholstery | Seat cushions flatten over time | Durability: cushion compression | High | Not in ISO 7176 |
| Exposure to fluids causes deterioration | Chemical resistance and waterproof testing | Not in ISO 7176 | ||
| Tearing and wearing of cushion and cover, loosening upholstery | Durability: ageing, tearing, abrasion, loosening | Not in ISO 7176 | ||
| Footrest | Broken footrests | Durability: strength | High | ISO 7176-8 |
| Difficulty in folding, adjusting for height | Durability: corrosion | Not in ISO 7176 | ||
| Brakes | Loosening and corrosion of locking mechanism | Durability: cyclic testing, ageing, corrosion | Low | Not in ISO 7176 |
| Frame and cross braces | Bent push handles | Durability: loading | Low | Not in ISO 7176 |
| Wear on coatings, coating deterioration | Paint chipping and corrosion | Not in ISO 7176 | ||
| Rusted holes, welds and areas where paint is chipped off | Durability: corrosion and testing folding mechanism | Not in ISO 7176 | ||
| Fasteners and arm pads | Bolts and pads loosen out | Loosening | Low | ISO 7176-8 |
| Pads deteriorate, exposing edges | Ageing and abrasion testing | Not in ISO 7176 | ||
| Rusted components | Durability: corrosion | Not in ISO 7176 |
Source: Authors’ own work
ISO, International Organization for Standardization.