hacker and lehner motor question
 

i am wondering if it is normal on a hacker or lehner motor for the shaft to spin very easily when turned with your fingers? my neu motors are hard to turn with just your fingers and are kind of "notchy" like they are grabbing but the hacker and lehner i have just roll super smooth. does this mean the magnet is fried or is this just normal for these german motors?

2 pole motor vs 4 pole, they are much easier to turn by hand vs a neu or medusa. It also depends on the stator (or strator, can never remember the spelling), and whether it is a slotted (notchy) or slotless (not notchy) design. If you have an IR temp gun and check your motor during or after a run, you will see if its overheating and in danger of demagnetizing or not- 180*F max.

No, lehners and hackers should spin smoothly by hand.

Yes, like Neil said... the lehners and hackers are slotless designs (Feigaos also), whereas a Neu is slotted stator (coils aren't criss-crossed).

To elaborate a bit-

Slotted motors have the stator coils wrapped through steel laminations (similar to a brushed motor) and the magnets on the rotor get caught at precise points where the poles of the rotor magnets align with the poles of the steel laminations (determined by the # of poles on each).

Slotless motors do not have the steel laminations in the stator coils so there is nowhere for the rotor magnet's poles to get caught on as it turns and so it rotates smoothly by hand.

Has anybody run across a 4pole or greater slotless motor? Just curious :yipi:

My tekin redline is a 3200 kv 6 turn delta wound motor. It has the same rotor and can size as the castle 1/10 scale motors (smaller than the feigao 540 S rotors). I don't know how the turns would be so low for such low kv without it being 4 pole, although the rotor is not 4 magnets which sort of contradicts the 4 pole theory.

I could be a quad pole single piece magnet... they don't make them very often anymore however.

Are these slotless? http://www3.towerhobbies.com/cgi-bin...?&I=LXLBS1&P=7

Does that mean on a 4 pole the '4 poles' will align with the stator at once and the 2 pole will only align 1 at a time?

OR a slotted motor just has more magnetic pull when not in use?:neutral:

Like 'What's Nitro' post, a slotless does NOT use iron in there stator (windings), instead relies on on the greater amount of 'turns' (think 7xl ,or 8xl...) to produce a certain level of impedence/inductance, hence Kv.

A slotted motor like the Neu's use iron(laminated) in the stator to produce impedance/inductance, and also need fewer 'turns' of the windings to produce a given Kv.

Is there a way to see if a motor has been demagnetized?

So it's only wire thats makes up the stator in a slotless, hence no magnetic pull in any direction ( no notchy feel )

Yes, wire and some dividers(structure) I believe. IIRC, the coils are overlapped slightly differently as well, but don't quote me on that.

Not necessarily. Like I said, the number of "notches" you feel in a slotted motor is determined by the number of rotor poles and the number of stator slots.

In the case of a Neu motor (15 series), it has a 12 slot stator and a 4 pole rotor. This motor has 12 notches that you can feel when you turn it. Since the # of poles can divide into the # of slots resulting in a whole number, the number of notches is equal to the number of slots. This works every time. IF you have a motor with say 6 poles and a 12 slot stator you will still feel 12 notches. If you have 4 poles and a 24 slot stator you would feel 24 notches.

AS far as 2 pole slotted motors (Novak, LRP, all the ROAR BL motors) they use a 2 pole rotor and a 3 slot stator. In this case the motor has 6 notches because only one rotor pole can align at a time- 2 poles * 3 slots = 6 notches. I'm not sure if this multiplication method works for any other type of motor. It is just my observation.