The utility model relates to a prevent release, assemble the pivot in the hole of barrel including the axis along barrel and rotation that the fore -and -aft direction extends, rotate the cover in the pivot and be equipped with the pressure cap, press the cap to revolve the dress and be in on the barrel, on the barrel in the front side of pressing the cap be provided with with press the sealed face of front end facial features to setting up of cap, the preceding terminal surface of pressing the cap with press from both sides between the sealed face and be equipped with the back sealing washer, back sealing washer with the rotary shaft seal cooperation. The utility model provides a sealed difficult prevent release who became invalid when pivot and the motion of barrel production incline between pivot and the barrel.