2151. CG Limits of a Ground Vehicle With Articulating Suspension and Interdependent Load Equalization

Paper

Abstract

This document describes a method to define the center of gravity (CG) limits for an special wheeled vehicle. SAWE Paper No. 1930, Vehicle Corner Stability and CG Limits, described a method for obtaining a vehicle center of gravity (CG) envelope based on vehicle corner stability and best driving conditions. This paper describes a method of CG envelope for a wheeled vehicle with additional limitations. The special vehicle referred to is the 60K loader, which is an aircraft cargo transport loader. This is a one unit, five axle line, diesel powered truck with a powered roller conveyor cargo bed (deck). The cargo bed is hydraulically elevated. Each of the five axle lines consists of two individual articulating dual wheel assemblies. Four of the axle lines are steerable. All axles are equipped with pneumatic brakes. Two of the axle lines are driven by four hydrostatic drive motors. The vehicle’s suspension is hydraulic cylinders interconnected with other axles to form a four point suspension system. This is accomplished by connecting the two left forward suspension hydraulic lines with each other, the two right forward suspension hydraulic lines with each other, the three left aft suspension hydraulic lines with each other., and the three right aft suspension hydraulic lines with each other. With this kind of suspension system, the two forward left wheels will have the same wheel loading, as will the two forward right wheels, the three aft left wheels, and the three aft right wheels. What makes this vehicle CG envelope unique is that the vehicle has a gross weight of 125,000 lb. with 20 tires, each tire has a capacity of 8,450 lb., and the empty loader.(65,000 lb.) has to be air transported adding another limitation of 10,000 lb. load on the forward axle due to the aircraft floor load limitation.