Abstract: Devices and methods for protecting against the theft of mobile equipment having at least one hydraulic cylinder (telescoping support member) that is extendable to a equipment immobilizing position, in which position the equipment is rendered immobile. A hollow strut which is dimensioned to receive the shaft of such a hydraulic cylinder and has sufficient length to maintain the hydraulic cylinder in its equipment immobilizing position, thereby maintaining the heavy equipment in its immobile state. The strut has two halves hinged to each other and is mountable about the shaft and lockable thereabout with an anti-theft locking mechanism. The anti-theft locking mechanism is concealed when the strut is maintaining the hydraulic cylinder in its equipment immobilizing position.