The hydraulic coupling bush (1) has a bush plunger (12) that is fixed at an inner piston (11) that is displaced parallel to an axis and is arranged within bush housing (4). An arrangement of the bush plunger, inner piston, pressure sleeve (13) and a holding sleeve (16) is displaced from uncoupled condition with a hydraulic coupling plug (2) up to an end position. The hydraulic coupling plug is locked with the hydraulic coupling bush by protecting elements (18) in the end position. Independent claims are also included for the following: (1) a bush arrangement, which has controlling spaces; and (2) a method for coupling a hydraulic coupling plug at a hydraulic coupling bush.
