axial vibration of camshaft
axial vibration of camshaft
(OP)
Thought problem -
What could cause significant axial vibration of the drive end of a camshaft (measured only at the cam nose), which worsens with increased engine load?
Application:
inline six-cylinder diesel engine
cam-in-head with roller followers
spur gear timing drive
Frequency of excitation not currently known. The motion is not believed to be related to dyno coupling problems, and has only been observed in a lab setting, but has never looked for in other settings.
Some things that I came up with
- axial vibration of the engine assy (due to coupling problem?)
- thrust loads from (spur) geartrain due to small misalignments, deflections of gears, crown offsets, etc
- torsional and/or bending strain of the cam somehow giving an axial displacement at the nose
What could cause significant axial vibration of the drive end of a camshaft (measured only at the cam nose), which worsens with increased engine load?
Application:
inline six-cylinder diesel engine
cam-in-head with roller followers
spur gear timing drive
Frequency of excitation not currently known. The motion is not believed to be related to dyno coupling problems, and has only been observed in a lab setting, but has never looked for in other settings.
Some things that I came up with
- axial vibration of the engine assy (due to coupling problem?)
- thrust loads from (spur) geartrain due to small misalignments, deflections of gears, crown offsets, etc
- torsional and/or bending strain of the cam somehow giving an axial displacement at the nose





RE: axial vibration of camshaft
BK
RE: axial vibration of camshaft
So I'd be looking at the tappet/cam interface.
That'd come through at firing frequency.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: axial vibration of camshaft
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It could happen if either the cam lobes are not ground exactly square, or the lifter bores are not machined exactly normal to the camshaft axis. A side thrust will be generated that tries to screw the cam out of it's bearing bores.
The way Ed Iskenderian described it, you remove the cam drive gear, and rotate the cam by hand with a socket brace, and it will be seen to move sideways after several turns. Reverse the direction and the cam will move in the opposite direction.
I could imagine if the machining were particularly bad on several lobes/bores, some sort of nasty axial vibration could be set up. I really don't know about any of this, it is just speculation.
RE: axial vibration of camshaft