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Thread: How to reduce clutch wear on disengagement?

  1. #1
    Associate Engineer
    Join Date
    Jul 2013

    How to reduce clutch wear on disengagement?

    This is a general question about using an automotive-style clutch to spin up a stationary load with a piston engine by slipping until the load has reached the speed of the engine.

    Intuitively, I would say the amount of wear on the clutch during the spin-up depends on three things:
    #1. The length of time during which it was slipping (more time = more total wear)
    #2. The speed difference between the load and the engine (more RPM difference = greater wear rate)
    #3. The force normal to the friction pads (i.e. pressure between pressure plate & flywheel) during slipping (more pressure = greater wear rate)

    My question is, if RPM is kept constant, what strategy minimises wear on the clutch during engagement? Gradually releasing the clutch with engine kept at low power/torque (big #1 and small #3), or dumping the clutch more rapidly with engine set to higher torque/power (small #1 and big #3)?

    P.S. In this system the clutch is operated by an automatic controller that keeps engine RPM constant during slipping, by varying clutch plate pressure (aka clutch engagement). So point #2 remains constant regardless of strategy, and #1 and #3 are taken care of proportionally. The only user input is engine throttle during the initial spin-up.
    Last edited by LMF5000; 07-07-2013 at 06:31 PM.

  2. #2
    Technical Fellow
    Join Date
    Feb 2011
    Hi L,

    You may want to look at alternative methods than a friction clutch. It depends on what things are important. You have not stated weight, size, HP and a whole host of other things. Is it a dry clutch, wet clutch, multi-plate, single plate.

    It gets a little tedious trying to guess what is needed. We are Engineers here and we work from facts. The design of things can change dramatically depending on scale, HP, materials etc. It is impossible to give answers to your questions with so little detail. Are you trying to move a 300-ton Military tank or spin up a 6" model gyro-copter rotor?

  3. #3
    Associate Engineer
    Join Date
    Jul 2013
    Hi Pinkerton,

    I'm an engineer too. I am looking for general answers about clutch strategy, so I didn't see the need for specific system info. But in any case, here is the info: single plate dry clutch, 100kW power, around 200Nm maximum torque at crankshaft (not more than 20% of this used during engagement though) typical engagement time 1.5-5 seconds. No active cooling. Use of a friction clutch is mandatory because one is already installed so no option to switch to a better mechanism for now.

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