The surge coil can also have an additional benefit depending on system design. As mentioned by other members in the previous thread on clutch springs, in certain circumstances the coil may act somewhat as a spring itself, to help absorb motion & prevent damage or leakage.

In the case of steel pipe/tubing there's something called Young's Modulus of Elasticity which speaks of how well a metal can withstand bending force without breaking. As in a leaf spring or coil spring, steel can actually bend in cycles throughout its lifetime with very little negative effect on the material's integrity.

Wall thickness of tubing or thickness of other forms/shapes certainly has an effect on failure rate. The same amount of bending force cycles applied to heavy metal may have no noticeable effect, where on a thin material it can cause total failure. That's like when you bend a small piece of wire back & forth until it breaks in two but your leaf springs can last 100 years!

The trick with a thinwall steel tube is to allow sufficient distances so bend effects are lessened, virtually the same as changing radius of a bend, plus proper anchoring. Here the metal can withstand more cycles or even infinite cycles without breakage. That said, a system designed with all factors of bend radius, length of run & modulus of eleasticity considered can theoretically last forever, minus other negative factors. So it's possible for a surge coil to offer another free benefit in addition to precluding shock waves and absorbing acceleration/velocity changes.

This linked page is interesting in that it shows that even the moorings & fastenings of pipes have to be calculated to consider bends, as the bends have a dynamic effect on the pipe itself! In other words the forces of a liquid negotiating a bend INSIDE THE PIPE can cause a failure in the anchoring blocks outside, it's that great of a force effect on piping! That's in addition to the effects on the liquid in the pipe! Pictures show the varying effects of radius of bend on flow of media whether liquid or gas:

[www.lmnoeng.com]

From these bits of information it becomes obvious that the strange little coil bent into Dodge truck hydro clutch lines is a result of piles of sheets of calculations plus many years of research, made long before computers did all the work for the engineers!