A few years ago it became obvious that the use of multi-wheel arrangements would become common on future main undercarriages, particularly on large aircraft. Four reasons for such use are: —

1. (i) Spreading the load on the runways allows operation of the aircraft from a larger number of aerodromes.

2. (ii) Reducing the individual wheel loads and tyre pressures allows operation of the aircraft from natural airfield surfaces.

3. (iii) An overall reduction in undercarriage weight may be achieved, particularly for large aircraft.

4. (iv) Ease of stowage in the aircraft structure when retracted.

The multi-wheel arrangement could be obtained by having the wheels side by side, in line, by having the wheels side by side, in line, or by a combination of these two methods.