Posts Tagged ‘piston’

Piston

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Piston is one of the main part of vehicle which is subjected to enormous thrust caused by burning of fuel and transmitting this trust to the rotary motion of the crankshaft. These are mostly made of aluminium alloy but sometimes, cast iron pistons are also used.It is made strong enough to withstand thrust caused in power stroke yet made light as far as possible as at the top and bottom of the stroke of the cycle the piston must come to a complete stop and start again in the opposite direction.

Considerable force is required to overcome the inertia of piston when it stops and starts. As the weight of piston affects the inertia, its weight is kept as light as possible. To reduce its weight, the skirt and head is made as thin as possible and to give desired strength ribs, are cast on the underside of the it to reinforce the area. These ribs also assist in conducting heat from the head of piston to piston ring and out through cylinder wall. Ribs are also used to reinforce gudgeon pin bosses. Previously pistons were manufactured by casting process. But now-a-days aluminium alloy piston are manufactured by pressure die casting process.

Function of Piston

When the piston moves from TDC to BDC in suction stroke, it produces a partial vacuum due to which fresh charge is sucked in i.e., it works as pump for taking air in the cylinder.Some of the piston have combustion chamber made in head for proper swirling action of air charge.It transmits the power produced in the power stroke to crankshaft.In Exhaust stroke, it pushed out exhaust (burnt) gases.It works as a guide for the upper part of connecting rod. It carries a rings which which seal combustion chamber from sump.It withstand high temperature and pressure in power stroke.

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