Abstract: There is disclosed a device for crimping couplings to the ends of hydraulic hoses in which a plurality of die means are located around an axis, camming means is provided and is arranged to cause the die means to move radially inwardly towards the axis when the die means and camming means are moved axially relative to each other, and a hydraulic actuator is provided for causing that relative axial movement. When a coupling is inserted between the die means, operation of the hydraulic actuator causes the die means to move inwardly and thereby compress or crimp the coupling. The hydraulic actuator has an annular hydraulic fluid chamber to which pressure is applied to operate the actuator. Further features are that adjusting means is provided, for pre-setting the outside diameter to which the device will crimp a coupling, the adjusting means being co-axial with the device for increased accuracy, and having a construction which involves no projecting parts, so as to avoid damage.