New 3doF platform construction

[IanH1960]

Still not sure how these worm-gear driven units would operate under a-symmetrical load. (like an unbalanced motion platform)

One way to think about worm gears is as other gearing but with lower efficiency - and even lower efficiency when back driven. Indeed if the conditions are right (small worm helix angle, high friction conditions etc) the back driving efficiency can drop to zero - ie the box locks. However locking is not a universal characteristic of worm gearing - many can be back driven.

Where this is the case the torque required at the motor end to "balance" the driving load can be a lot less than it would be in higher efficiency sets such as spur or helical gears. So you have a circumstance in which load deceleration and load holding is made easier for the motor. However the price to pay is that the internal sliding friction effects that help here also hinder when it comes to driving the load - the input driving torque needs to be higher than it might be because of the inherently poor worm gearing efficiency.

If the loading is unbalanced then worm gearing assists decelerating and holding it, but also makes it harder to accelerate and drive the load (though not by the same ratio). The question arises is one worth the other.

I think one reason for specifying worm gearing is because it provides a convenient and possibly cheaper way of achieving a large reduction ratio than multistage spur reduction or epicyclic gearing. If I had the money my high reduction box of choice for a platform drive would be epicyclic- compact with good efficiency - that and a well balanced platform to keep the actuator loads to a minimum in any case!

..probably just confusing things now - it's late!

Ian

[kermit]

Hi,

A wormwheel gear has always the same ratio gearwise And called I= with a number .
We have a program wich calculate the highest for seen loads and give a advised ratio .
When we sell spudpolewinches that have to pull out poles on waterway`s or grounds we use frequenty inverters that counts the speed of the mass being pulled,and will ajust the motor speed and therefore the speed of the wormwheelgear.
greetz Henk

[wannabeaflyer]

Hi Guys thanks for the info and links about wormgears .. i did not mean to detract attention away from the great work Roland has done, it was just over the years the balancing act for DIY motion simmulator Builders seems to me, to be the comprimise required regarding Weight , Inertia,and The real bugbear cheap easyish to make actuators, using common non expensive but accessable parts ( Utopia diy sim actuator wise ) i suppose what little i have managed to pick up is, their is not at present a simple fix to this and its guys like Roland, Ian and Jim over at Cheap motion cockpits NZ that have really lead the way in giving hope for those of us out there that still have that Dream making ( finishing ) our own motion platforms . so Keep on doing what your doing Roland and the rest of the innovators, i for one always eagerly await to see what you guys develop cos it is always done with the DIY Guy and Common basic Skills in mind and that in itself is great news Cheers