Many machine types Levers A basic machine with a pivoting bar at a fixed location. This fixed point is referred to as the fulcrum. Load input force is classified into three categories. First, there is direct load input, which consists of only gravitational forces acting on the lever. Second, there are indirect load inputs, which consist of loads applied to an intermediate object that in turn applies force to the lever. Indirect loads can be further divided into two groups: active forces and passive forces. Active forces include forces generated by motors, gearboxes, and other devices that use energy to create movement or apply force. Passive forces include gravity and friction. Lever action is used to classify machines. The type of lever most commonly associated with levers is called a "bar-shaped" or "tripod" lever. Other names for this tool include push-pull tool, toggle tool, and crank-cam mechanism. It is a simple mechanical device used to transmit force from one point to another. Force is transmitted from a moving body to a static body to which it is not attached. The term "lever arm" is also often used to describe the length of straight metal or plastic tubing that connects a pivot point on one end and a rigid projection on the other. The projection can be a pin, hook, or some other shape; it simply needs to have more weight than the arm itself.