Lengthwise displaceable, pressure medium charged, hydraulically blockable adjustment assembly

A lengthwise-adjustable, pressure-medium charged, hydraulically blockable adjustment assembly comprising:

• an outer cylinder;
• an inner cylinder fitting coaxially within said outer cylinder and having a sealed off face at one end thereof, said sealed off face exposed to the outside;
• a piston displaceably mounted within said inside cylinder, said piston separating in a sealing, fluid-tight manner, said inside chamber into first and second housing chambers;
• a piston rod connected to said piston and extending sealingly outside of said cylinders at the end opposite said sealed off face;
• first and second axially displaceable separating pistons disposed in the annular space between said outer and inner cylinders in a fluid-tight manner and defining a first annular chamber on the side of said first separating piston opposite said second separating piston, a second annular chamber between said first and second separating pistons and a third annular chamber on the side of said second separating piston opposite said first separating piston;
• said inner cylinder having a passageway through the wall thereof in the vicinty of the sealed off end thereof;
• sealing means for sealing off said passageway in one position of said inner cylinder and for permitting access to said second annular chamber when in a second position;
• connecting means for permitting fluid access from said housing chamber on the side of said piston which is connected to said piston rod to at least a portion of said first annular chamber;
• pressure means within said second annular chamber for urging said first and second separating pistons apart;
• and
• substantially non-compressible fluid filling said first and second housing chambers and said first and third annular chambers;
• whereby said inner cylinder may be axially displaced between a locking position at which said sealing means seals off said passageway and said piston is locked and a releasing position at which said sealing means permits access of said passageway to said second annular chamber and said piston may move.