Abstract: Every one of us might have seen the heavy trucks running on the roads. These vehicles have efforts on their axles very close to the allowed limits, mainly driving on rough roads or during cornering. In this case, the use of conventional suspension systems like those using McPherson Struts, Multi Link Suspension, Trailing Arm Suspension, 4- bar suspension etc. can increase the axle’s overload phenomena.

Hydropneumatic suspension system, when used in these vehicles, takes an asset in providing a better load distribution per axle, decreasing the overload problem and thereby increasing the ride comfort. The well known problem of the damper co-efficient changes due to load variation in vehicles using conventional suspension system is even more observable when a hydropneumatic spring is applied due to its non linearity, as opposed to the several advantages this spring type brings. This problem is more emphasized in vehicles with a large mass range when they pass from a no load condition to a full load condition.

In this study, a Mathematical model of the hydropneumatic spring stiffness behaviour was developed. The various factors or parameters that influence the spring stiffness behaviour have been mathematically found out. Also in this paper, a methodology for primary specification of critical parameters of a hydropneumatic suspension system is presented.