are used to : - Tegnologie

Pawl and ratchetA ratchet mechanism is based on a wheelthat has teeth cut out of it and a pawl thatfollows as the wheel turns. Studying thediagram you will see that as the ratchetwheel turns and the pawl falls into the 'dip'between the teeth. Ratchets are usedwidely in lifting equipment to lock themotion and prevent reverse rotation whenthe input force is remove. Ratchets canalso be used to drive a motion in onedirection and allow free-wheeling in thereverse direction.Chain and sprocketA chain is made up of a series of links withthe links held together with steel pins. Thisarrange makes a chain a strong, long lastingway of transmitting rotary motion from onegear wheel to another.Chain drive has one main advantage over atraditional gear train. Only two gear wheelsand a chain are needed to transmit rotarymotion over a distance. With a traditional geartrain, many gears must be arranged meshingwith each other in order to transmit motion.4