Low Price Bulk H91400-1 Hydrodynamic Retarder Thermostat Assembly Accessoires For JAC Dongfeng FAW JH6 Truck Transmission System Features Precision Cooling Control : The H91400-1retarder external thermostat automatically opens and closes cooling channels based on coolant temperature fluctuations. It regulates the proportion of coolant flowing into the radiator, ensuring the retarder operates within the optimal temperature range. Dual-Valve Structure : The dual-valve design