The tiny ZWO AM5 weighs in at 5kg and carries loads up to 20kg. Harmonic drive with zero backlash.
My workhorse was the Skywatcher NEQ6-Pro rated for a 20kg load. It carries max 10kg, usually 5 or 6. It should be balanced properly – with all breaks loose, gravity should induce no movement in any of the axis.
Equatorial mounts are built to allow movement in two perpendicular axis, one of which must be perfectly parallel to the line of local latitude. Errors in latitude alignment, tracking speed and mechanical faults in the endless screw that drives it (periodic error) makes tracking imperfect; over time, the errors accumulate and drift appears. The software of the mount can compensate for periodic errors and the rest can be corrected with an auto-guider. Or you can ignore them.
Installed on a secondary instrument parallel to the main one, the auto-guider is a camera that connects to the mount and gives it real-time instructions to compensate when the star it is aimed at starts drifting. I use a standalone guider, meaning it connects directly to the mount without going through a laptop. Guiding may not be as precise as through a computer, but i cannot deal with the hassle.
The auto-guider port on the EQ6
The other mount I use is the Takahashi Teegul SP-3 capable of carrying about 2-3 kg. It’s portable and works perfectly with the 60mm refractor and the m6.