Abstract: In order to meet the requirements in making maintenance of impact-hammer crusher, a hydraulically-actuated crusher casing open/close mechanism is developed. The basic structure and operating principle of the mechanism are introduced. For ensuring the safe and reliable operation of the mechanism, the position equation of the mechanism is established with analytic method. Kinetic and static analysis is made with an aim to determine the relationship between the stroke and transmission pressure angle of the casing opening cylinder and casing opening angle, the relationship between the casing opening angle and the cylinder′s push-pull force and force of constraint of pivot support, and the static load parameters of the motion pair for strength verification. Solution and analysis indicate that for enabling the mechanism to achieve a 35° opening angle, the cylinder′s retraction and stretching-out values are required to be 817.63 mm and 1 219.76 mm, respectively; with the increase of the opening angle of the box, the pressure angle of the cylinder′s push-pull force increases, deteriorating the transmission performance; when the opening angle of the movable box is around 31°, the pressure on the cylinder becomes smaller, and a double safety protection can be ensured if protective support is fitted on the box structure in this case; when the opening angle of the feed box is around 25°, the centroid of the box is directly above the pivoting point, providing safety protection in this case, owing to the facts that the cylinder is under no pressure, the shear force to which the pivot shaft is subjected is exactly the gravity of the crusher′s feed box, and the safety coefficient of the pivot shaft can be checked by the gravity of the feed box. The casing open/close mechanism in finalized design features a simple structure and a wide range of opening angles. When the casing is opened for maintenance, the cylinder is subjected to a minimal pressure, making it possible to provide a much improved safety protection. The mechanism can be widely used on similar heavy-duty crushing equipment.