The piston may be connected to the upper end of the connecting rod either directly (trunkpiston type), or indirectly (crosshead type).
活塞与连杆上端的连接，既可以是直接连接(筒状活塞式)，也可以是间接连接(十字头式)。
2
The compressor is a trunkpiston style compressor. It is derived from a proven oil field compressor frame that has been modified for the demands of high-pressure compression.
超高压压缩机为整体撬装式结构，此种结构来源于油田应用，经不断改良而适合于高压压缩机的要求。
3
In trunk-piston engines, a horizontal pin within the piston is encircled by the upper end of the connecting rod. This by far the most common construction.