Most open press machines use crank and connecting rod mechanisms for operation. The transmission principle diagram is as follows: the crank and connecting rod mechanism is a mechanism that converts rotary motion into reciprocating linear motion. The reciprocating linear motion of the slider is applied to the upper mold to use punching force to push the sheet metal down and complete the work.

The crank press transmits the motion and energy of the electric motor to the crankshaft through the transmission system, causing the crankshaft to rotate and the slider to reciprocate through the connecting rod, thereby achieving the motion and power requirements of stamping processing.

Electric motor 1 drives the crankshaft to rotate through pulley 2, small gear 3, large gear 4 (flywheel), and clutch 5, and then drives slider 7 to reciprocate in the guide rail of the machine body through connecting rod 6. Fix the upper mold on slider 7 and the lower mold on the machine worktable. The press can then drive the upper and lower molds to apply pressure to the material, and use the mold to make the workpiece. Clutch 5 is operated by a foot pedal through a control mechanism, which can move or stop the crank slider mechanism without stopping the motor.

The brake and clutch work closely together, and the crank slider mechanism can be stopped at a certain position (usually at the top dead center of the slider) after the clutch is disengaged. The large gear 4 also functions as a flywheel, ensuring even and efficient utilization of energy in the electric motor load.