Controlled by two small pneumatic pistons, the clutch can engage and disengage, as well as change the resistance needed to “slip” the clutch. This works because the pistons can “sandwich” the two halves of the clutch, thus engaging it. The harder the pistons sandwich the clutch, the more resistance it takes to make the clutch slip.
A very capable trial truck that I designed especially for driving on soft sands and in shallow water. There was a big risk of getting salt water and sand in the electronics and gears, so I gave it a lot of ground clearance and angled the shocks in so that they will be more stable to prevent rollovers.
I compiled all the pictures and video clips I could find about the new lego 9398 rock crawler. It appears to use the unimog balljoints for the 4-wheel steering with two motors onboard the axles for propulsion. The motors are new, though the battery box is still the old one commonly found in lego sets. Rumor is that the steering motor is a new pfs servo!
The rc unit that came with my lego 8376 hot flame racer has no auxiliary output. So, I came up with this design, which uses the pfs polarity switch to turn the aux output on/off. The polarity switch is controlled by the return to center steering output on the rc unit. Overall this design works very well, except it is not very practical because you need an external battery box.