Patent ID: 7513178

Claim:
A hydraulic screw tensioning device for tightening and loosening highly stressed screws or bolts having an elongate threaded end ( 4 ), comprising: a cylinder ( 5 - 8 ) adapted to be supported on a machine part ( 1 ) that is adapted to be clamped by a threaded bolt ( 2 ) and a nut ( 3 ) adapted to be threaded onto said threaded end ( 4 ); at least one piston that is guided in a sealed manner in said cylinder ( 5 - 8 ) and is adapted to be periodically supplied with pressure; a change sleeve ( 21 ) comprising a threaded portion ( 22 ) adapted to be threaded onto a threaded end ( 4 ) of said threaded bolt ( 2 ), wherein said at least one piston is adapted to rest against said change sleeve ( 21 ); a pressure medium connection fitting ( 45 ); a rotary sleeve ( 15 ) disposed in said cylinder ( 5 - 8 ) and adapted to be positively connected with said nut ( 3 ), wherein said nut is adapted to axially slide along said rotary sleeve ( 15 ); a first gear mechanism ( 47 ) adapted to be in driving connection ( 16 ) with said rotary sleeve ( 15 ); a second gear mechanism ( 9 ) adapted to be in driving connection with said change sleeve ( 21 ) at its end opposite from said threaded portion ( 22 ) remote from said first gear mechanism ( 47 ); a single drive motor ( 24 ) for said first and second gear mechanisms ( 47 , 9 ); a connecting shaft ( 33 ) disposed between a gear ( 32 ) in said second gear mechanism ( 9 ) and a gear in said first gear mechanism ( 47 ); a device ( 25 ) for an alternative coupling of said drive motor ( 24 ) with said change sleeve ( 21 ) or with said rotary sleeve ( 15 ), wherein said device ( 25 ) for an alternative coupling comprises a gear ( 25 ) that is adapted to be displaced between engagement with said gear ( 12 ) secured to said change sleeve ( 21 ) and a driving connection with said first gear mechanism ( 47 ) for said rotary sleeve ( 15 ), and wherein journal pins ( 34 , 35 ) are provided on said displaceable gear ( 25 ) and are displaceably disposed in slots ( 31 ) in a lower gear mechanism housing part ( 10 ) and an upper gear mechanism housing part ( 11 ); and respective hexagonal or square means ( 18 , 49 ) on a gear ( 12 ) secured to said change sleeve ( 21 ) and on said gear ( 32 ) in said second gear mechanism ( 9 ) and adapted to positively receive a tool for driving said connecting shaft ( 33 ).