Abstract: A quick fastener for mounting a hydraulic cylinder to a casing, whereby the hydraulic cylinder has a fastening device, and the casing has mounting structures in the casing wall. The mounting structures act in concert with the fastening device so that the hydraulic cylinder can be mounted to the casing wall without using tools. The fastening device includes primarily a fastening nose and a catch spring with a catch nose, as well as, a stop collar or groove. The mounting structures include at least one opening in the casing wall that have contours into which the fastening nose as well as the catch spring with the catch nose can be inserted. The advantage of this quick fastener lies in the simple sealing of the chambers on both sides of the casing wall, with a simple assembly, by inserting, in the direction of the axle of the hydraulic cylinder, and the swinging or positioning, as desired, of the hydraulic cylinder into the mounting position.