1. Test of repeatability

a. No inspection is necessary as long as upper working bench locking cylinder can be inserted, and the clearance between copper sleeve and axle shall not be too large.

b. Test method of repeatability of lower wirking bench: placea working bench in the rear part of the lower working bench and fix two dial indicators on it. Record the pressure values of the dial indicators as m. Make reciprocating movements of lower working bench, and record the movement values as m1, m2, and m3, with the difference between the larges value and smallest value as repeatability≤0.05mm.

2. Test of flatness of upper and lower working benches

Place 4ф50 round bars of the smae height ( or blocks of the smae height ) under the working bench, to make the main cylinder decrease to the round bars of the smae height. Apply pressure <10kg/cm2, and measure the clearance with plug gauge (0 for three bars, while the remaining as the flatness of the upper and lower working benches), and change positions of the round bars of te same height.

3. Test method of demagnetizing effects

a. After magnetizing of the magnetic disk, spray iron dust on the surface (on many points), and check if the iron dust is in the shape of magnetic force line after demagnetizing.

b. Carry out demagnetizing after magnetizing, place a small piece of iron plate on two polarities respectively, and fetch them slightly to see if there is any suction force.