C-shaped plates are installed on both sides of the fuselage, and high-precision grating ruler is installed on the C-shaped plate, so as to avoid the influence of fuselage deformation on bending accuracy during bending.

The oil cylinder movement drives the sliding block to move up and down. After the grating ruler can feedback the position of the sliding block to the system, the latter will issue the position adjustment command according to the real-time input data.

The electro-hydraulic servo valve and grating ruler are used to form a closed loop control for the main oil cylinders on both sides synchronously, so that the feedback is accurate and the sliding block runs accurately, so that the bending accuracy and the repeated positioning accuracy of the sliding block are high.

The back gauge mechanism with complete functions is adopted, and multiple back gauge can be selected and controlled. The functional parts in the back gauge, such as guide rail, ball screw, bearing, etc., all use high-end high-quality accessories to ensure the accuracy of the back gauge.