[Craig Sawyers]

If it does not move to its unloaded position, you get the same result by using the ratio of cylinder pressure to atmospheric pressure. So if the cylinder pressure is 3 bar, the relevant ratio is B = 3 and hence the resonant frequency is about 0.3Hz. That will be quite high Q and hence legs have quite careful viscous damping using oil and orifices, which means that the legs start to operate (ie to attenuate) at about 1Hz.

It is more complicated than that, because they have to deal with horizontal excitation too, so the legs also have pendulum mechanisms too (also damped) to handle that.