Friction torque is the force between two objects that causes one of them to rotate about an axis. It shows how much power results from one object spin the other after accounting for power lost to friction between the objects. For example, when a player throws a bowling ball down an alley it does not slip together on one side, but rather spins in a circle as it rolls. The friction from the floor makes contact with the ball creating torque, or twisting force, and the ball spins around its own axis. This axis is not real, but can be considered an invisible line that goes directly through the center of the bowling ball around as it rotates.
Torque is a force acting on an object, such as the floor of the bowling alley acting on the bowling ball. Traditionally, a force pushes an object forward or pulls it down. Instead of pushing or pulling, torque refers specifically to a force that causes another purpose to rotate. If a rope was tied around a wheel and a heavy object placed at the end of the rope, gravity will pull the object downward, which represents a traction, while the weight of the object will rotate the wheel, so that torque represented by torque.
Cars take advantage of torque to make the wheels of a car turn. An engine creates power that gets the pistons inside it up and down. This force only pushes and pulls, however, and cannot turn wheels by itself. To solve this problem, the pistons rotate a crankshaft which in turn rotates the flywheel that connects to the car’s gearbox. All of these parts eventually transfer rotary motion from the crankshaft to the car’s wheels, which then begin to roll forward.
Frictional torque action on an object is a result of the resistance caused by the friction between two objects subtracted from the original amount of force. When a bowling ball rolls along the floor, the friction between the floor and the ball slows it down a bit. Its total friction torque, how fast it is to turn, is the original strength when you cast it minus the forces of friction with the floor slowing down. Torque measurements are expressed in Newton meters or pounds-feet.
Effects caused by frictional torque can create problems in machines that need to hit accurately and not slip. To control friction torque in these machines, torque limiters are often used. Friction torque limiters create a snug space between the moving parts to ensure they rotate at the desired speed. This is especially important in production equipment and related machines.
- Pistons rotate a crankshaft which in turn rotates the flywheel that connects to the car’s gearbox.