How would you make a good pivot-arm suspension? I once tried to make a 4 wheeled Lego robot using a pivot arm suspension system. The robot was motorized using 2 Mindstorm (2.0) motors (one one each side).  I can't find and original picture but it looked like this big black one:



I used a Lego Technic turntable as the single point of rotation between the two robot sides bu the robot sagged a lot and there was so much pressure on that piece that it would not rotate well.



Q: How would you build a 4 wheels rover pivot arm suspension system? Considering that it needs to be motorized thus adding the weight of two motors. 

Note: The pivot arm design can be one of those two:


Edit 1: To give an idea of the size, I'm using this Technic wheels. The final model is about 20cm long and 20cm wide.
I got inspired by the idea of a vertical Slewing Bearing.  I made this “horrible”  prototype to demonstrate the principles.



One side of the assembly has a fixed wheel attached to it using multiple pins. The other side has multiple bearings.  The idea is that the vertical weight is shared between the bearings (on one side) and between the pins supporting the wheel  (on the other side).  This way, the axle supports only a part of the weight.  In the final design the axle should be much longer and use many bushes preventing the two sides from separating.