Automotive Q & A

Knowledge Database - Timing Belts

Question: The Function of Timing Belts

Answer: Timing belts allow your vehicle’s engine to operate. They connect your engine’s crankshaft to the camshaft and play a vital role in controlling the pistons and valves in your vehicle. Simply explained, the timing belt is a reinforced rubber band with teeth or notches on the inner side that precisely synchronize the opening and closing of the engine’s valves. As the crankshaft turns, it sets the timing belt in motion. The timing belt then turns the camshaft and opens or closes each valve and allows the pistons to move up and down. For instance, in a four-stroke engine there are four phases: the intake phase, compression phase, combustion phase, and exhaust phase. In the intake phase, air and fuel get pulled into the cylinders. In this phase the intake valves are open and the exhaust valves are closed. In the compression and combustion phases the air and fuel is mixed, compressed, and then ignited by the spark plugs. During these two phases all of the valves are closed. The final stage is the exhaust phase where the air and fuel that remains exits out of the exhaust valve. In this phase the exhaust valves are open and the intake valves are closed. The timing belt must control all of the opening and closing of the valves and the timing of the pistons throughout each phase. The timing belt allows each step to occur in the precise order.

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