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Gday
I teach thiings similar to this this to undergrads daily however there are a myriad of variables in an astronomy GEM that seperate it from simplistic lever ideas taught in engineering statics. I might add that i am a geotechnical engineer (Dr Dirty) - about as far from a mechanical engineer as you can get I suppose and my comments are based on astro experience not professional experience.
Yes (simplistically) if there is a moment (force x distance) induced by a scope (that is perfectly balanced in the plane at 90 dergees to the dec axis - usually not!) then it can be visualised as being balanced by a moment at the counterweight end. This moment can be a F X D that is the same as the product of F X D at the other end so that the system is in equillibrium. as D increases F can decrease.
Going past simplicity - (and I look forward to comments from some mechanical guys) - this simplistic idea does not take into account things such as deflection (a function of the size of the moment and the size (shape and dimensions) and material properties of the counterweight bar). Even though the two moments may be balanced if the load is too high then you can induce deflections beyond the capacity the mount with obvous consequences.
The most obvious I think is that the gears and worms are not (I think) positioned at the balance point of the system. Thus as deflection increases the force the gear is jammed onto the worm is increased causing serious binding problems and subsequently causing motor burn out etc. (happens a lot).
A good mechanical engineer wil no doubt offer a more technical expansion on this and other problems but my comments would be that mounts are built the way they are built for a reason and load limits are given for a reason. Yes the designer will have built in a factor of safety allowing some slight overloading however as creatures that like pushing limits we tend to keep pushing (I am guilty of overloading a HEQ5 Pro too - solved it by getting a EQ6 Pro).
If however you are within the reccomended limits of the mount and you want to decrease the amount of counterweights carried (ie the fXd = f/2 x 2d ie the same moment) - it may work however there are probably other things that could be induced such as resonances etc that mech guys may comment on.
My 2c worth anyway
Bolts
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