Patent ID: 7219913

Claim:
A trailer for use as part of an articulated vehicle, the trailer including: a main chassis pivotally connectable to a wheeled section of the vehicle immediately ahead of the trailer so that said wheeled section can articulate relative to said main chassis about a substantially upright first axis in the main chassis; a sub-chassis having a plurality of pairs of ground-engaging wheels mounted thereto and longitudinally spaced apart theralong, said sub-chassis being connected to the main chassis for free pivoting about a substantially upright second axis in the main chassis; stop means adapted to define a maximum angle of said free pivoting by said sub-chassis away from a position of longitudinal alignment with said main chassis, said maximum angle being dependent on the positioning of said stop means relative to said main chassis; stop positioning means for automatically positioning said stop means relative to said maximum angle is variable according to the positioning of said stop means; steering means responsive to relative rotation of said sub-chassis and said main chassis about said second axis for steering at least two said pairs of steerable wheels relative to said sub-chassis in such a sense as to tend to align said sub-chassis longitudinally with said main chassis, each of said at least two pairs of steerable wheels being mounted to a respective rigid axle assembly, each said axle assembly being pivotally mounted to said sub-chassis, each of said at least two pairs of wheels being steerable by pivoting of said axle assembly about a substantially upright third axis in said sub-chassis, in an opposing direction to an adjacent said pair of steerable wheels; and first locking means whereby when said sub-chassis is in longitudinal alignment with said main chassis and any angular deviation from longitudinal alignment of said wheeled section and said mean chassis is less than a specified value said locking means is operable to hold said sub-chassis and said main chassis in longitudinal alignment.