This invention relates in general to articulated vehicle hitches and, in particular, to a tilt limiting apparatus for controlling the amount of tilt between units of the articulated vehicle.
More specifically, this invention relates to apparatus for limiting the amount of tilt between the tractor unit and the trailer unit of an articulated vehicle which will equalize stresses placed on the components when limiting the amount of tilt.
During operation of articulated vehicles, it is frequently necessary and desirable to allow the units forming the vehicle to tilt relative to each other to keep all of the vehicle wheels in ground contact when traveling over uneven surfaces to prevent the loss of tractive effort. However, the amount of tilting movement between the vehicles must be controlled to maintain vehicle stability. Various types and kinds of tilt control systems have been known in the art such as the use of an elongated rocker bar adapted to pivot about a horizontal axis when the trailer unit tilts relative to the tractor. Such a system is disclosed in U.S. Pat. No. 1,990,731 and utilizes two pairs of upper and lower fixed stop members positioned above and below the rocker bar at opposite ends thereof to limit the relative tilting between the tractor and trailer units. These stops include resilient elements normally contacting the upper and lower end portions of the rocker bar to cushion or reduce the impact incurred in stopping the relative tilting between the tractor and trailer unit. When the trailer tilts relative to the tractor, one end of the rocker bar compresses the resilient element of the lower stop on one side while the opposite end of the bar compresses a resilient element of the upper stop at the other side to cushion or reduce impact incurred when stopping the movement of the ends of the bar. While such mechanism may be suitable for some applications, the resilient elements wear out losing their elasticity and must be replaced by attaching new resilient elements in proper alignment with the stop engaging surfaces of the rocker bar. After repeated use the resilient stops wear unevenly and thus localized high stresses develop in the hitching apparatus.