Hydraulic cylinder barrel and cylinder piston rod due to the accident after bending, generally to be straightened on the pressure machine.However, the cylinder or piston rod straight after the colonel of the press will often rebound after a period of time, that is, the cylinder or piston rod to a certain extent to restore the original shape.For this reason, some repair shop after a long time of exploration, developed a long cylinder bending straightening machine .When in use, put the bent cylinder or piston rod into the straightening machine, press the clamping wheel, start the motor and roll it back and forth. Adjust the clamping wheel continuously according to the situation, and straighten the bending cylinder or piston rod slowly.This is different from the straightening in the pressure machine, straightening in the straightening machine, not only can straighten the bending part, and cylinder cylinder or piston rod because of bending the internal stress can be released under the repeated action of the upper and lower rollers, to ensure that the straightening in the school does not bounce back.