When it comes to the selection and use of fasteners, among the most important concepts that the user must grasp-and it's the one that's most often misunderstood-is torque. In simplified terms, torque represents how tightly parts are joined together with the fastener. In the case of an alternator bracket, for instance, the fastener, typically a hex-head machine screw, joins the bracket to the engine block with enough force that the two can't move independently. If they're able to move even a tiny bit, the fastener may hold them together for a while, but it will soon back out completely. Therefore, the primary mission of nearly all fasteners, rather than simply ensuring that components remain attached to each other, is to minimize movement between them. To ensure that fasteners are properly torqued-especially for such critical fasteners as engine and drivetrain components-nothing short of a torque wrench will do.