During a recent conversation I had with Dr Marian Tumarkin, co-author of 'Hydraulics Made Easy' and 'Advanced Hydraulic Control', we discussed the reasons why newbies to the hydraulics biz often have trouble grasping the concept of 'Power Beyond'.
Marian, who has a lot more classroom teaching experience than I, made the point that while students tend to grasp the circuitry easily enough, they have trouble relating it to the actual configuration of the physical valve.
In a nutshell, Power Beyond is a facility in the outlet section of a mobile directional control valve, which enables the pressure bypass gallery to be isolated from the tank gallery.
By doing this, the pressure gallery can then be carried over or continued on to the P port of another directional control valve (DCV). Hence the term Power Beyond (the first DCV) and its other name: High Pressure Carry Over (HPCO).
Some time ago I recorded a simulation video for 'Hydraulics Pro Club' which explains the configuration of Power Beyond in detail. And I've just posted the first 10-minutes of it on YouTube.
So if there are any gaps in your understanding of Power Beyond, set aside 10-minutes of your day and watch the video here.