QUOTE (neil_s_wood @ 20 Oct 2008, 10:09)
<{POST_SNAPBACK}>After the discussion elsewhere about MFX decoders and that ESU will be offering support for these in use with ECoS, I had been reading up on them. Whats the difference between a "coreless" and a "all current" motor? How do I know which is which
***Hello Neil
You don't ask easy questions do you
!!
You really don't need to even think about this whole thing anyway - MFX is nothing special in this area as all current quality decoders are pretty well fine with 2 wire DC coreless motors (all it needs is a high frequency or "silent drive".
Coreless do exist in some EU models but are not all that common: I sometimes use them in the locos I build but not often.
The usual description of a normal DC motor is an "iron core motor" - conversely a coreless motor has no mass of Iron as part of the armature structure hence the name coreless.
BTW In this case I suspect that the ESU "all current" description is yet another blurring of clarity through yet another poor ESU translation effort.
The following imperfect info will give you the general differences...
The structure of the motor types is totally different - there is as stated above no Iron core in a coreless motor and so its moving mass is much less allowing much faster motor accelerations and greatly improved smoothness (the whole of the armature is the windings - often strengthened with a layer or epoxy or simlar for rigidity). They will also often be brushless - those which do have brushes usually having much smaller brushes than a standard DC motor - and they are always of precious metal such as gold.
They are very very efficient and smooth but because of the lower physical mass of the armature structure (ie its made up of only the windings with no Iron pole pieces) they are not very strong torque wise and are also very sensitive to bearing pressures and can be poor at handling higher direct loads as there is no real strength in the moving parts of the motor.
Because there is a low armature mass, they cannot dissipate heat well either. However when the drive and the motor are properly matched they make a super smooth and very very efficient drive system - so heat will then not be an issue.
So... its not just a matter of changing one for the other - Unless the motor is designed for the job to be done then the whole of the drive train may need to be changed to prevent inwanted bbering forces that would destroy the coreless motor.
Example is Portescap - its gearbox uses all helical gears which are very efficient and tend to not load the motors thust bearings. As a esult, you cannot safely substitute traditional worm drives which are very inefficient (only about 30% of motor power in a worm drive gets to the wheels).
A bit of web searching will probably show some structural illustrations if its of interest.
