My Tractor Forum banner

Replacing the PTO electric clutch coil.

21K views 11 replies 5 participants last post by  Behr72 
#1 ·
This procedure takes about 2 hours with replacement coil on hand (Recycling vendor contact at end of post). Replacing the coil in the PTO is necessary when the PTO coil degenerates into a dead short in the electrical system, end result, blowing the fuse on the PTO circuit, and the machine says, no cut,no grass,no more. The coil itself is a controlled near short to form a magnetic field that engages the magnetic clutch, (which in turn, turns the PTO). In most cases only the coil needs to be replaced, not the entire clutch, which can cost a small fortune if you can find it..



After you take the hood off, sometimes side panels you will get down to the meat of the problem, the clutch itself. Remove 4 bolts that hold clutch shroud and remove. Unbolt pulley from shaft and slide off. (Older machines may require puller), now we are down to the last piece of the inside part of the clutch (which slides on the woodruff key to engage clutch) "when it is turned on". Slide it off the shaft, now we have reached the root of the problem, (one fride coil).



Remove the 4 studs and remove coil. One has to stop and think why this coil is mounted directly to the transferring heat from the block with no stand off, not good design, but there is nothing we can do to change this as the tolerances are too tight to rectify this problem, moving on.



We take the new coil, and using a Snowman trick to center it, because the holes are bigger than the studs that mount/center it. We take O rings and put them on the top two studs and center the coil to the shaft.



After the top two studs are hand tight, and clutch is centered to the block, install bottom studs and tighten with rachet. Then take out top two studs, take off o-rings, reinstall and rachet tight, now coil is installed.
Slide on first part of clutch over coil and spin to check for any rubbs, then slide on pulley and bolt to shaft.



Add four springs to studs then install outer shroud over pulley leaving about a 1/8 heavy inch between the shroud and the pulley. (look at bolts for gap)



Attach wire from coil to tractor, and get busy cutting the grass, you are done.
 
See less See more
6
#2 ·
Forgot to mention recycled coil is $150 from (4th pic up ) machine shop wound with heavier wire than stock, 27 coils made in the last two years 0 failures. He may need your coil to recycle if he has no stock of your unit. He is on ebay, but if you contact him directly you may get it a little cheaper than I did (ebay fees). Very well packed for shipping.
 
#4 ·
hi this is jonwaally, a new pto clutch from jthomas lawnmower parts TROY BILT/BOLENS PART # 1744401, THOMAS PART # OR26 is about $250.00+ sh $12.00 he may have new field coils for about 75.00. Ogura ma gt bn1. also you have to mike the coil through the cover windows from .010 to 015 recommended is .012 .otherwise you may have early failure do to wobble inbalance in magnetic field. you may not notice it. ck bolens manual on pto instillation. good luck. jonwaally@yahoo.com or here.
 
#5 ·
hi again this is jonwaally. if you look at the back of the field coil you will see some indentations. small bumps caused by stamping in manufacture. they center the field coil in the crankshaft seal cavity, very snug fit. makes it a lot easier. no force needed and dead center. jonwaally
 
#6 ·
Ahh, I was wondering what they were, just thought they were a punch out for a bigger shaft. Onan was a 1 1/8 and the Kohler is a 1 1/4.

Since these coils were known to go bad, I felt like not buying into maybe the same bad batch # of New (old stock), does that make sense? But I could only find a part #, not a batch # of production.

Thanks for the tips.
 
#7 ·
Some more details for testing coils
--------------------------------------------------

NOTE; IMMEDIATE SHIPMENT NOW AVAILABLE - NEW REBUILT UNITS ON HAND.

REBUILDING with New Field Coil for replacing 12 volt Ogura MA GT - BN1, BN2 and B2 field coils used on KOHLER ENGINES by EXCHANGE with 1 YEAR WARRANTY - AVAILABLE FOR SHIPPING FROM STOCK, WITH EXCHANGE -

28 SOLD AND INSTALLED WITH NO ISSUES OR WARRANTY NEEDS OVER 2 YEARS REBUILDING.

FIELD COILS FOR OGURA MA GT BN1, BN2, BU2 AND B2 ARE EXACTLY THE SAME WITH THE SHAFT SIZE OF 17 AND 18 HP BN1 UNITS USUALLY 1 1/8" WITH 1 1/4 FOR THE BN2AND B2 ON LARGER ENGINES.

TESTING A PTO CLUTCH IS EASY WITH A MULTI-METER - RESISTANCE SHOULD BE OVER 3 OHMS WITHOUT REMOVING THE PTO, JUST DISCONNECTING THE WIRE AND CHECK RESISTANCE (OHMS) TO THE FRAME OR GROUND. THE LOWER THE OHMS THE WORSE THE CONDITION BECOMES. MOST CIRCUITS ARE DESIGNED FOR 5 AMPS, SO THE CIRCUIT LIMIT IS REACHED AT ABOUT 2.4 OHMS. UNDER 2 OHMS IS PUSHING 6 AMPS AND BEYOND THE CHARGING CIRCUIT AND FUSE RATING.

EXCHANGE rebuilding service replaces your housing with a new coil potted in place in a stock housing and soldered to ground with positive lead thru case, as original . Old housings are then cleaned and prepared for the new field coils.

NOTE; Some of the later Troybuilt PTO clutches use this field coil on 20 HP engines. SOME B&S ENGINES ALSO USE THIS FIELD COIL

MORE INFORMATION AT 40196 52221 / FRANK

Shipping costs at net OR Local Pickup with exchange of housing- must receive your old housing for shipping rebuilt unit. Male / Female 1/4" fast on connectors supplied

FREE SHIPPING BY USPS PRIORITY MAIL - DISCOUNT FOR LOCAL PICKUP

BEST WAY FOR RETURNING OLD CORE IS USPS PARCEL POST
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top