The Valve Train

1
The Valve Train

• Camshafts, Rocker Arms and Push Rods

Presented By- David Smith
2
Objective

• To familiarize the audience with the purpose and
  uses of
• The valve train
• The pushrod system
• Alternatives to the pushrod system
• New developments in the valve train world

3
Role of the Valve Train

• Times the opening and closing of the cylinder
  valves
• Ensures opening and closing is kept in sync
• Necessary for any combustion engine

4
Components of the Valve Train(Pushrod System)
Rocker Arm
Camshaft
Head
Springs
Valve
Cylinder
Pushrod
http//www.oregoncamshaft.com
5
Overhead Cam Systems

• Positions the camshaft in the head(s)
• Single overhead cams (SOHC) are found in inline
  cylinder engines
• Dual overhead cams (DOHC) are found in
  V-cylinder type engines

6
Advantages/ Disadvantages of the overhead cam
system

• Creates the possibility for more fuel or exhaust
  valves
• More valves More flow
• Like pushrod systems, will only be 100 efficient
  at a specific RPM.

7
New Technologies

• Hondas VTEC (variable valve timing and lift
  electronic controls)
• Lobes can be enabled/ disabled at different RPMs
• Allows for variable timing
• creates more low and high end RPM power

8
New Technologies cont.

• Ferraris VVT System (variable valve timing)
• Uses 3D lobes
• Aggressive lobe profile at one end, opposite lobe
  profile at the other
• Blended together in the center to form a varying
  lobe shape
• Camshaft moved in and out depending on the RPM

9
Ferraris VVT system
Camshaft Moves Laterally
Varying Lobe Design
10
Conclusion

• By explaining the components and different
  types of camshafts that go into a valve train,
  you now have a more profound under standing of
  the system and the combustion engine as a whole

11
References

• http//www.streetracersonline.com
• http//www.oregoncamshaft.com
• http//www.hotrodder.com
• http//auto.howstuffworks.com

If cylinder heads are the heart of an
engine, then the camshaft and valve train have to
be the brains of the operation. -www.streetrac
ersonline.com