Electro-hydraulic suspension control for low floor light rail vehicles

The inherent space constraints associated with low floor light rail vehicles (LFLRV) and the requirements for high performance systems are demanding new developments in vehicle suspension technology. It has become increasingly difficult to accommodate the weight, space, and additional costs associated with a pneumatic suspension system in order to maintain a high ride quality and satisfy vehicle height control. Some low floor LRVs utilize passive, conventional suspension systems (e.g. coil springs and dampers), which provide a lower ride quality when designed for compatibility with platform heights under various load conditions. While certain LFLRV suspension requirements can be fulfilled with a passive suspension system, not all user needs are met. With the demands for vehicles to comply with the Americans with Disabilities Act (ADA), additional needs for bridge plates or other suspension controls are also required. A new electro-hydraulically controlled suspension system has been developed to directly respond to these needs. It is now possible to utilize a highly responsive hydraulic suspension system which maintains a stable car body ride height under varying load conditions and which provides the ride comfort expected from a pneumatic suspension system. Further, by taking advantage of the existing electro-hydraulic brake system components on a vehicle, this system is able to reduce the number of additional components. This paper describes the electro-hydraulic suspension system, designated HPF