Removed a flywheel from a Kohler CV18 engine. I dropped one of the magnets, and it broke pretty much exactly in half ! When I epoxy them (magnets) back in the fly wheel should I equally space the brake point of the broken one (equal space as other magnets) or keep the brake in the broken one as close as possible together.
Kohler CV18 Flywheel Magnet
1 - 8 of 8 Posts
Joined
·
5,747 Posts
If you can 'mate' the broken pieces together closely(snugly), such that there is no gap, then do that. Magnetism will have a small field that 'leaks' if you were to sprinkle iron filings on a piece of paper over the joint, but the majority of the magnetic field will flow through. Along that line, if there are small 'chunks' that keep the two pieces separated, I'd remove the chunks if that would get a better meeting of the pieces.
If you add a gap, you are changing the timing of the pulses, adding two smaller ones in place of one larger one. The 'leakage' pulse will be minimal in comparison, IMO.
I have glued together a broken ferrite rod AM radio antenna successfully, and that is the same type of material in flywheel magnets. It likely does not perform as well as a new, undamaged rod, but still gets the stations.
tom
If you add a gap, you are changing the timing of the pulses, adding two smaller ones in place of one larger one. The 'leakage' pulse will be minimal in comparison, IMO.
I have glued together a broken ferrite rod AM radio antenna successfully, and that is the same type of material in flywheel magnets. It likely does not perform as well as a new, undamaged rod, but still gets the stations.
tom
Joined
·
20,933 Posts
I'm not sure that will work...instead of having one magnet with one north pole and one south pole,when it brake in two,you now have two magnets that EACH have a north and south pole,which might screw up the magneto's operation,it depends on the induction and collapse of the magnetic feilds to operate and make spark at the correct time.....only thing I can say is try it,if it works,it'll be interesting to know...
Glued and equally spaced the magnets to the fly wheel, and kept the broken one as tight as possible ( no glue between pieces).....let set up overnight, replaced the flywheel and started the engine, the amp meter is showing charge........I think it works. However what precipitated the disassembling of the fly wheel was negative charging when engine running. When PTO switch was engaged or brake released the engine would die ( Husqvarna YTH180 tractor). Figured there wasn't enough electrical power to engage the PTO (replaced PTO switch), engine still dies. The seat occupied switch seems to work, I will check the brake switch and see what happens.
Joined
·
5,747 Posts
'holic, If you remember 8th grade physics {Longmeadow Jr High back in 1961-2}, when you put two magnets together {the way where they like each other} and put them under a piece of paper sprinkled with iron filings, the magnetic field developed more or less 'flows'(?) from tip-to-tail right on through, and doesn't 'leak out' as it would when they are separated. The closer the bits fit together, the better the field is contained. You do get a bit of leak, but the high majority will be kept in check.
Take a piece of magnet, such as the flexy one on the refrigerator door seal, and break a piece off. Put the two pieces together and do the paper test. I'd bet my paycheck {$0} that you'll see what I describe. But it's your refrigerator and The Boss might not like you snipping bits of it off for experimentation.
tom
Take a piece of magnet, such as the flexy one on the refrigerator door seal, and break a piece off. Put the two pieces together and do the paper test. I'd bet my paycheck {$0} that you'll see what I describe. But it's your refrigerator and The Boss might not like you snipping bits of it off for experimentation.
tom
Joined
·
20,933 Posts
I didn't have physics in 8th grade,just a science class..
I was a magnet fan as a kid though and did read a lot about them and fooled around with them..never did try the test you mentioned with the iron filings,I suppose its true that two "separate" magnets put end to end with the opposite poles attracting each other could act as one single one though...I figured because it was one magnet broken into two peices,it would act as two separate ones,especially if the glue kept the mating surfaces insulated from each other..
The magnets in question were for the charging system,not the magneto for ignition??..in that case its likely it would still work to produce a charge with a damaged or even missing magnet at a reduced rate,but I think a magneto is much fussier about having everything "perfect" for it to work...
I know the tecumseh I had with magnets that came unglued off the inside of the flywheel for the magneto never did run good after I re-glued them on,possibly not in the exact spot they were intended to be in..I ended up swapping a used flywheel on it that had a magnet casted into the flywheel and it once again ran good..
I tried reading up on how magnetos operate,but quickly got lost after the chapter on "end gap" and all the other technical principles of its operation...I understand the basics,but not the whole theory..
I was a magnet fan as a kid though and did read a lot about them and fooled around with them..never did try the test you mentioned with the iron filings,I suppose its true that two "separate" magnets put end to end with the opposite poles attracting each other could act as one single one though...I figured because it was one magnet broken into two peices,it would act as two separate ones,especially if the glue kept the mating surfaces insulated from each other..
The magnets in question were for the charging system,not the magneto for ignition??..in that case its likely it would still work to produce a charge with a damaged or even missing magnet at a reduced rate,but I think a magneto is much fussier about having everything "perfect" for it to work...
I know the tecumseh I had with magnets that came unglued off the inside of the flywheel for the magneto never did run good after I re-glued them on,possibly not in the exact spot they were intended to be in..I ended up swapping a used flywheel on it that had a magnet casted into the flywheel and it once again ran good..
I tried reading up on how magnetos operate,but quickly got lost after the chapter on "end gap" and all the other technical principles of its operation...I understand the basics,but not the whole theory..
Joined
·
5,747 Posts
You're right. It was science class. I made it to being on TV on WBZ as our schools 'science whiz' back then. Of course, I doofed it up on camera in the first show. But it was a long ride to Boston to the studio, so I likely would not have been able to continue anyway. Did get to see Quabbin(sp?) reservoir though.
I think a magneto needs to have its magnets placed in exact positions to fire at the proper time. That is why a sheared flywheel key will cause kickback in a lot of cases. The magnets are passing by the 'gizzards' a bit sooner than is desired, so the generated spark is earlier than desired. The flywheel in most cases continues to rotate a bit relative to the crankshaft after impact that shears the key. When you try to crank it over, the flywheel is there just a little bit too soon as the extra rotation excites the windings too soon, and then collapses too soon. Magnet done get there and gone before its spozta as the flywheel is spun past its proper timing spot.
tom
I think a magneto needs to have its magnets placed in exact positions to fire at the proper time. That is why a sheared flywheel key will cause kickback in a lot of cases. The magnets are passing by the 'gizzards' a bit sooner than is desired, so the generated spark is earlier than desired. The flywheel in most cases continues to rotate a bit relative to the crankshaft after impact that shears the key. When you try to crank it over, the flywheel is there just a little bit too soon as the extra rotation excites the windings too soon, and then collapses too soon. Magnet done get there and gone before its spozta as the flywheel is spun past its proper timing spot.
tom
1 - 8 of 8 Posts
