Engine Valve Train

Jeff Barker

Valve Train

• Parts of an engine that move the valves

How do the Valves move?

• Camshaft rotates at the same speed as the crankshaft.

• Lobes on the camshaft push up rockers as the shaft rotates

• Rockers push down and open valves

Pushrod Valve Train

• Camshaft located inside the engine

• Rocker arm connected to the camshaft by a pushrod.

• More weight• Smaller engine

Single OverHead Cam

• Camshaft is on top of the cylinder in direct contact with the rocker arm

Double OverHead Cam

• Two camshafts instead of one on top of a row of cylinders

• Four camshafts in a V-engine

• Produces more power with additional valves

• Centered spark plug• Larger engine, more

parts to maintain

Future valve trains

• Pneumatic valve train – used in Formula 1 engines to reach 17,000 rpm

• Springs are replaced by pressurized air

• Computer controlled valves?

Sources

• http://auto.howstuffworks.com/camshaft1.htm • abbysenior.com/mechanics/valve.htm• http://www.swcp.com/mcs-bin/Exp_Image.cgi?

img_src=images/VTrain99/RRockHead2.jpg• http://en.wikipedia.org/wiki/Four-stroke_cycle• http://www.supercarsunlimited.com/info/tech/

stem/adj22.jpg