A website based in the Netherlands has some great graphics showing how fluid power (hydraulic and pneumatic) components work. Visuals are simple, two-dimensional drawings, but color coding and animation are effective at conveying basic principles.
So if you have colleagues who need some basic training in fluid power or have trouble visualizing how things work, you might want to refer them to this site.
However, there's more to this site. It describes a three-gear pump (at right, top). Gear pumps and motors can already transmit extremely high power in a small volume, and this concept seems to take it further: increase output by 100% while increasing the size only 50%. In fact, as long as the components are strong enough, you could probably use this concept to make a three-gear motor with twice the torque capability of its conventional counterpart.
A similar concept along these lines was described in a short article I edited earlier this year — the February 2011 issue, to be exact. In the article, I describe how a mechanical engineer modified a standard gear motor to provide two outputs (at right, bottom). He did this by replacing the idler gear with one having a shaft extension. Of course, he also had to use a side plate to accommodate the second output shaft. But this was done successfully, and both output shafts run at exactly the same speed. This could prove useful in many applications, I'm sure.