Abstract: A drilling or service rig (1) for use in operations on- or offshore, the rig (1) being formed by a derrick structure (3) projecting from a foundation (11) and being arranged to receive a carriage (7), movable along the longitudinal axis of the derrick structure, for a drilling or service device (17), the carriage (7) being arranged to carry out, under the influence of at least one double-acting hydraulic cylinder (9, 15), a relative movement along the longitudinal axis of the derrick structure (3), and at least one of the at least one cylinder being formed by a double-acting, telescopic cylinder (9) which is arranged to exert both a push force and a pull force on the carriage (7), whereby the said carriage (7) is moved respectively away from or towards the foundation (11) of the rig.