|
This discussion has been had a few times !
I think you will find that a mount is rated for a given payload based on all the standard supplied counterweights being in use.
It is for mine !
Some manufaturers specifically state both the "Payload" and "Total capacity" separately (which spells this out quite clearly), most only state Payload and dont specifically state what defines the real Payload.
If you add more counterweight to the original OEM weights you are actually decreasing (not increasing) the usable payload in terms of scopes - as far as the manufacturers safe ratings are concerned.
These are based on bearing loads, gear contact surface pressures, motor torque loadings etc
If you can remove a certain amount of counter weight then you can add extra payload.
Most mechanical equipment is designed with some certain amount of safety margin built in, some isn't designed its just built !
That doesnt mean the ratings can necessarily be ignored.
Now I realise that this is not what everyone is doing - generally if more scope weight ends up on top then the common thing to do is to add more weight at the bottom and people have done this for a long time and assume its OK.
Its only OK till you wear out your mount prematurely (bearings, shafts bushes and gears) or things get overloaded - motors stall or burn out or otherwise compromise the tracking ability of the mount.
The truth is its not OK but we all overload our 6x4 trailers too - dont we !
If there is any argument, I suggest a letter of request should be sent to the manufacturer to clarify what is Payload and what is the Total Capacity including counter weights.
The exception to this is some of the new robotic mounts with harmonic drive motors where there are no counterweights. In these the actual torque load of your payload is more important than the simple mass of your Payload. eg - two payloads of the same mass - say a refractor and a large diameter mirror - the large mirror being over the rated capacity of the mount whereas the refractor will be OK simply due to torque loading as the mirrors centre of mass is much further away from the axiis of rotation. (its slightly more complicated than this - but its close)
Cheers
Rally
|