The cooler adopts a dual structure, consisting of two oil coolers with the same area and a three-way valve device, one working and the other standby. Each cooler can bear the cooling load of the entire system. One end of the tube plate is fixed, and the other end is a floating, detachable tube bundle and water chamber cover, which is easy to clean, inspect and maintain during operation. The material of the cooler can be selected from various options based on the usage location and water system conditions.