A trailing arm suspension unit for use on a vehicle including a ring bearing, a trailing arm, a spring and damper for providing large vertical wheel travel in a jounce and rebound suspension condition. The ring bearing may include external threads for rotationally connecting the trailing arm to a mounting plate or a hull of the vehicle. Further, supply lines for electrical and fluids may be passed through the opening in the ring bearings without the use of a slip ring and passed through a passage in the trailing arm to a wheel on the vehicle. The spring and damper may be located on top of the trailing arm and separately connected to the mounting plate to generate significant mechanical advantage. The geometry of the spring, damper, and trailing arm allow the spring in the suspension unit to be gas cylinder employing air.