Hydraulic suspension system for a vehicle cab

A road vehicle cab attitude controlling apparatus comprising:

• frame means supported by wheels of the vehicle;
• cab means mounted on said frame means and adapted for receiving occupants of the vehicle;
• cab suspension means mounting said cab means on said frame means and allowing relative movement therebetween, said cab suspension means comprising a plurality of seats each supporting a different portion of said cab means and at least one said seat being detachable therefrom;
• cab actuator means for activating said cab suspension means to adjust vertical displacements between said frame and said seats;
• an engine mounted on said frame below said cab means;
• auxiliary actuator means for producing pivotal movement of said cab means off of said one seat to provide access to said engine;
• cab sensing means for detecting vertical displacements between said frame means and a plurality of spaced apart portions of said cab means and the vertical displacement between said frame means and said one seat;
• and
• control means for controlling said cab actuator means in response to said cab sensing means, and operable with said cab means supported on said one seat to maintain a given attitude of said cab means with respect to a road surface, and operable with said cab means detached from said one seat to establish a predetermined vertical displacement between said frame and said one seat.