People usually associate the word 'motor' with the internal combustion engine but the accurate definition is simply something giving or producing motion (for example motor nerves etc.). The easiest way to get confused about the Dryvtech 2x2x2 is to confuse the term 'Engine' (which supplies power for the pumps) with the term 'Motor' (which converts hydraulic energy back into rotary motion).
There is one hydraulic motor in the hub of both the Dryvtech's wheels, they have 5 pistons arranged in a radial configuration and high pressure oil is directed into the area above the piston forcing it down against a 5 sided block which in turn applies force to a stationary eccentric (a 'crankshaft' if you like), hence turning the motor and wheel. The picture shows the motor hard up against the wheel- the 2 or 3 (of 5) caps that can be seen are actually the cylinder heads of the motor. The fabricated wheels (18 & 21 inch) bolt direct to the motor housings which spin with the wheels. These wheel motors are modified industrial units.
The pipes that run parallel to the swingarms also cause a little confusion. Of the 3 small hoses on top 2 are steering pipes - you can see them connected to the steering slave ram in the shot above (painted silver). The third is the motor 'case drain'- a high pressure hydraulic motor leaks internally in exactly the same way as a petrol motor. Like the case breather in internal combustion engines- a hydraulic motor must drain this excess fluid off -in this case it is returned to the oil tank via a filter - rather than just vented to atmosphere.
Many people think these small lines carry the drive oil but the high pressure drive oil is carried in the 2 large pipes that the 3 smaller hoses are clamped to. In fact no high pressure oil is carried in hoses at all - all HP is routed through solid steel pipes and complex pivots- these pivots are actually concentric with the high pressure oil on the inside and the return oil flowing "around" the outside of the HP tube. This is an absolute engineering nightmare- particularly where the suspension and steering pivots meet - however it all worked very well except for the system pressure blowing up some of the internal steel transfer tubes like balloons! There is one of these joints at each end of the pipes- one near the engine for suspension movement and 2 in the hub- 1 for suspension & 1 for steering lock.
Basics : Engine : Pump : Motors : Braking : Steering : Chassis