I thought i’d Got my head around Peters Ballards explanatory write up on GoMoG. Now thanks to this thread I am not so sure.
The bit I don’t get is that he states the two springs (main spring and rebound spring) are in series so the initial total stiffness is the addition of both spring rates. As I see it, since only one spring is compressed when the axel block is moved by a bump this is not the case? Surely the main spring compression is initially aided by the (partly compressed) rebound spring so it effectively reduces the stiffness of the main spring and “softening” the bump effect?
Peter Ballard says:
"So although there is in ‘our’ case one spring above and one spring below the hub, these springs are actually in parallel, not series"
The springs are similar to 2 springs in parallel. For having 2 springs in serie, they must be on the same side of the axle block.
When the axel block is move up by a force F:
the main spring (k1) is compressed,movement +dx mm
the rebound spring (k2) is released, movement -dx mm
When you write the equation of equilibrium of forces (sum of forces=0):
F-k1.dx+ k2.(-dx)=0
F=(k1+k2).dx
When both springs are in contact, the stiffness is equal to k1+k2 and you get the maximun stiffness of the suspension. It is counter intuitive.
