Spring preload and load...

[Rat5]

Hello, can someone explain me something i struggle a bit with ?

Lets assume a spring / mass system (like the corner of a car )


If i have a linear spring, with 10kg/mm and i put
300kg of preload, the spring will be compressed 30mm.

Now lets assume the corner of the car is 400kg, when you drop the car it will only begin to compress at 300kg and when it is fully resting the spring will be compressed a total of 40mm right ? (400kg/10kgmm=40mm)

This is correct i believe.

However i read on a suspension book, that if you have 300kg of preload, if you put 100kg mass on the top of this spring it will compress an additional 10mm ! How ???

You have to exceed the preload, for the spring to compress further, right ?

Thanks

 

[GregLocock]

Sounds like either you have misinterpreted the book or it is wrong. A typical example is a coil over where there will be a preload of about 300N, and as you say it won't even start to move until a load greater than that is applied.

Cheers

Greg Locock


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