液壓扳手的工作頭主要由三部分組成，框架（也叫殼體），油缸和傳動部件。油缸輸出力，油缸活塞桿與傳動部分組成運動副，油缸中心到傳動部件中心這個距離是液壓扳手放大力臂，油缸出力乘以力臂，就是液壓扳手理論輸出扭矩，由于摩擦阻力存在，液壓扳手實際輸出扭矩要小于理論輸出扭矩。
Hydraulic wrench is the abbreviation of hydraulic torque wrench. It is powered by hydraulic pressure to provide large torque output,
A professional bolt tightening tool for bolt installation and disassembly, which is often used to tighten and loosen bolts greater than one inch.
The hydraulic wrench is composed of working head, hydraulic pump and high-pressure oil pipe.
Through the high-pressure oil pipe, the hydraulic pump transmits power to the working head to drive the tightening or loosening of the rotating nut of the working head. The hydraulic pump can be driven by electricity or compressed air.
The working head of hydraulic wrench is mainly composed of three parts: frame (also known as shell), oil cylinder and transmission parts. The output force of the oil cylinder, the piston rod of the oil cylinder and the transmission part form a motion pair. The distance from the center of the oil cylinder to the center of the transmission part is the amplified force arm of the hydraulic wrench. The output of the oil cylinder multiplied by the force arm is the theoretical output torque of the hydraulic wrench. Due to the existence of friction resistance, the actual output torque of the hydraulic wrench is less than the theoretical output torque.
