Adopting original factory precision casting technology and made of pressure-resistant alloy material, it features compact and precise overall structure with excellent compression resistance, wear resistance and air tightness. Internal parts are well matched with high assembly precision, ensuring sensitive pneumatic transmission and stable rapid gear switching. Suitable for pneumatic operating system of heavy-duty truck transmission, it remains free from air leakage, stagnation and failure under long-term alternating air pressure and working vibration. With solid workmanship, good interchangeability and easy installation, it can perfectly replace original parts and greatly reduce maintenance costs.