mounted to platform 30 at pivot 76 and is lengthened or shortened by pneumatic or hydraulic pressure to retract or protract the wheels as can be seen from fig6 retracted and 7 protracted vehicle 2 has a prime mover 4 driving road and marine transmissions the power train includes primary shafts 60 which each drive an intermediate shaft 62 which connects to and drives hub 54 the intermediate shaft 62 extends within the tube 40 substantially co axially with the tube 40 the tube 40 will absorb loading on the wheel 8 which would otherwise have to be absorbed by the intermediate shaft 62 the tube 40 provides a lower suspension arm for the suspension by arranging the shaft 62 in the tube 40 there needs to be only one aperture though the hull to accommodate both which aperture can then be sealed by plate 34 the suspension will thus comprise the upper suspension arm 56 which is forked see fig7 at its inboard end so that it can resist fore and aft loads on the wheel 8 and a lower suspension arm in the form of the tube 40 as can be seen in fig3 the centre line of the wheel 8 will be displaced vertically by some distance from the point of connection of the inboard end of the tube 40 to the shaft 64 thus lateral forces on the wheel 8 will develop.