Skywatcher dobsonian mount 'control' handles

[Jimtheslim]

So, one of the handles has some kind of ball bearing set-up which is apparently some kind of control. I've used mine several times and have no idea what it controls. It seems to serve the same purpose as the non-control handle in that you tighten it as much as you desire to still be able to tilt the scope, then move or nudge it using the little black knob at the top of the scope. The handle is redundant. Am I missing something?

[Cornelius Varley]

The left hand handle controls the amount of friction between the telescope and mount. It should be adjusted so that the telescope doesn't drop under its own weight but is still easily moved up/down by the user. Page  5 of Dob6-Dob12 manual

[Jimtheslim]

I understand the concept, but I just don't understand what the added bearings provide that the other side does not, like if it needed replacing I don't know why you couldn't put one on without the bearings

[Cornelius Varley]

The tube sits on four teflon trunnion bearings, two either side. If the the telescope didn't have a method of controlling the movement of the telescope up and down then the telescope would not stay in a fixed position. The special bearing on the left side of the tube can be adjusted, by the use of the tension adjustment handle, to give the right amount of friction to stop the telescope dropping down under its own weight. The telescope only needs one of these friction adjustment bearings, the other side is just a pivot holding the the telescope on the trunnion. Once the correct tension is set in the bearing all that is needed is to adjust the elevation of the telescope is a gentle nudge, the tube will then stay in the new position.