Abstract

A study was conducted to develop a hydraulic normal loading device for a single wheel test rig available in the Agricultural and Food Engineering Department of IIT Kharagpur. A hydraulic circuit was designed to apply additional normal load up to 2000 kg on wheel axle. The same circuit also can be used to remove 1350 kg load from the initial load. The circuit uses a fixed displacement pump, a 3-way-4 port-solenoid operated- spring centered directional control valve, a pressure relief valve and a double acting hydraulic cylinder. The normal load is sensed by a ring transducer and recorded in a data acquisition system. This device was used to study the effect of normal load on a radial-ply tire (14.9 to 28) under soft and hard soil condition. It was observed that, with hydraulic loading device the normal load on the wheel axle under dynamic condition was found to increase in the range of 1 to 5% for soft and hard bed soil surface.

Key words: Static normal loads, dynamic normal load, radial-ply tire, drawbar pull, slip.