Air spring for cab of heavy truck with automatic height adjustment

A vehicle comprising:

• a cab with an air spring apparatus with automatic height adjustment, which is provided between the cab and a frame of the vehicle and supports the cab with a pressure of air filling in the air spring apparatus, the air spring apparatus comprising:
• a canister in which an internal space is formed;
• a guide provided within the internal space of the canister;
• a piston movably mounted in the internal space of the canister and configured to ascend and descend relative to the canister, wherein the piston includes an intake port and an exhaust port, and
• port opening units provided adjacent to the intake port and the exhaust port of the piston, and configured to come into contact with the guide, respectively,
• wherein the guide includes:
• an intake guide including an intake guide surface inclined outward the canister toward a lower side of the canister;
• and
• an exhaust guide including an exhaust guide surface inclined inward the canister toward the lower side of the canister,
• wherein when the cab ascends or descends, each of the port opening units is operated by the intake guide and the exhaust guide to open either the intake port or the exhaust port, and
• wherein the intake guide surface and the exhaust guide surface have unsymmetrical profiles to each other.