January 2000


Just on time with moving our manufacturing and assembly departments into the new premises on 6050 W EASTWOOD AVE #201, Piper company received a bulk order for 6 ring type hydraulic nuts.

Each of the 16 pretensioning devices for M68 bolts is pressurized simultaneously and generates a total pretensioning force of 9.700 kN. The outer diameter of the cylinder is 1460 mm and the total pretensioning force is achieved at 900 bar hydraulic pressure.

The ring type hydraulic nuts are part of product group PG13 and, in this case, equipped with mechanical lock nuts.

Advantage of this design:
All 16 bolts are pretensioned with exactly the same tensioning force. Each piston area is connected with appropriate bores in the cylinder rind so that the hydraulic pressure is the same all over and all bolts are pretensioned with exactly the same force. After the pre-detewrmined pressure has been reached, all lock nuts on the cylinder ring are screwed down by hand and the pretensioning force is kept permanently in the un-pressurized state of the device.