Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


clutch damage law

clutch damage law

clutch damage law

Hi all,

I have recorded torque and rpm of the crank shaft during some conditions. I need to understand which conditions is more "damaging" for the main clutch, for example many engangement with low torque and low rpm or few engagements with high torque and high speed levels. For the gears I have computed the time at level and then I calculated the damage with the inverse power law, computed with the three different damage exponent according to the failure mode. Is there any similar method for the clutch? Any other suggestion is welcome
Thank you

Best regards

RE: clutch damage law

I've known a few drivers who have never had to change a clutch in any of their cars even at 100 kmiles.

Generally from a start or when shifting they engaged the clutch quickly, at low rpm, so there was little slippage.

RE: clutch damage law

i would think that the most "damaging" operation would be starting from a standstill (especially on a steep gradient). in that situation there is initially quite a bit of slippage that will cause wear. during shifting operations the load is much lower, although that may depend on the behavior of the operator.

RE: clutch damage law

Hi all,

thanks for your reply. Greg is right, I need a sort of equation that would permit to understand which is the most severe condition for the clutch. I do not need an absolute value. I contacted the clutch supplier but he wasn't of great help

RE: clutch damage law

Well, the clutch isn't a torque multiplying device. So, say you have the engine at X rpm and are slipping the clutch to produce Y rpm. You will also have Z torque being transferred to the transmission. By using speed and torque on both sides, you can then calculate input and output power and the difference goes into the clutch (XZ - YZ). I would have to believe the higher the number the more clutch wear but I can only guess about that relationship being non-linear with more damage quicker as the clutch reaches a certain temperature.

RE: clutch damage law

I may be captain obvious but Hi RPM/harsh engagement of the clutch will cause rapid heating/pressure at the point of contact ,I would think it would be possible under full demand such as a 'peel out' for the clutch to slip under its full pressure higher gears such as 3.73 in the mustang svo may help with the pressure/heat over time to full engagement

RE: clutch damage law

@TMoose, maybe I miss something but with the uniform theory I might be able to calculate the Torque in function of the axial force and not something related to the remaining life of the clutch.

@Greg, your link is really helpful. In my opinion the key is on the energy which goes into the clutch for each engagement as we know the energy of friction forces is proportional to wear and a clutch has no remaining life when it is completely worn out. Unfortunately I do not have any temperature of the clutch surface, but I suppose higher is energy and higher might be the temperature reached by the clutch disc, therefore I would use the Archard's law and I would weight the engaging energy with an exponent, something like:


k proportionality factor
T torque
ω slip velocity
A exponent
H is material hardness

Since k and H are related to the clutch I can say

W ∝ (T*ω)^A

and this number I can use it as clutch usage severity. Does it make sense for you? Moreover, look at figure 5 of the following paper, do clutch mununfactures usually provide this kind of plot in their datasheet?


Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


White Paper - How to Capitalize on HVAC/R Trends to Drive Business Growth
According to Steve Yurek, CEO of the Air Conditioning, Heating and Refrigeration Institute, the HVAC/R industry is facing change on all fronts. This includes challenging trends on contractors and distributors like new refrigerants, growing automation, complex sensors and monitoring, green initiatives and a technician shortage. We look at these trends and outline actionable insights on how it all can be turned into a competitive advantage and business opportunity. Download Now
eBook - Manufacturing the Cars of Tomorrow
In this ebook, we'll explore how additive manufacturing is going to transform the way cars are made. This includes commentary from thought leaders such as Ford's CTO, Ken Washington, Customer case studies of ways 3D printing is being used today, and a variety of part examples where 3D printing is already impacting how automobiles are made. Download Now
White Paper - Smart Manufacturing for Semiconductor
New technologies and approaches present great opportunities for semiconductor manufacturers to achieve high levels of innovation, yield and improvement. This white paper explores some of these cutting-edge technologies and how they can be applied effectively in the semiconductor industry. Read about how Smart Manufacturing is transforming the semiconductor industry. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close