A hydraulic suspension strut (30) has a first on-off valve (58)
connecting
the first and second chambers (42 and 44), and a second on-off valve
(62) connected to chamber (42) only. Suspension arm (3) of
wheel (1) can be retracted beyond normal road travel, or protracted to road
travel mode, by use of pump (9) and valves (58 and 62). The
space in the strut above port (56) may be used as a hydraulic bump stop.
An accumulator (50) may be included, as a hydraulic spring. Alternatively,
strut (70) (FIG. 6; note alternative accumulator position) allows
suspension to be raised above normal road travel. Strut (100) (FIG. 8)
may be operated in roadgoing, raised, or retracted mode. These struts may be applied
to reconfigurable suspensions; particularly for amphibious vehicles, which may
require wheels to be withdrawn above the hull water line to reduce drag on water,
particularly during cornering.
