HydroPneumatic suspension systems have several main advantages over other suspension types: - They are well-suited for heavy load applications over 12 tons and provide independent leveling control and load stabilization. - They allow for a more stable suspension force and spring rate compared to other suspension types, as well as better control over suspension frequency. - HydroPneumatic suspensions are necessary when level control is needed frequently, such as for adjusting to major load changes, or when a manual operator control of suspension level is desired. They are robust for harsh working environments.