Abstract: A hydraulic cylinder that locks into position has a housing (1) with at least one pressure connection (7) and a piston (3) and rod (6) that travel tight in an out of the housing. The locking mechanism comprises a piston (11) that rests against a spring (35) and a barrier mechanism (23) with a cage of balls (25) that roll radially into a locking position in a locking groove (26) and back into an unlocking position in an unlocking groove (22). The primary piston communicates with a hollow space (18) and acts on a primary participating surface (19) and the locking piston communicates with an unlocking space (13) and acts on an unlocking surface (14) by way of the pressure connection. There is a variable choke (17), which disengages after a while, beween the pressure connection and the primary space (18) in the primary piston (3).