A couple of years ago, I bought a used Toro ProLine mower (walk behind, hydro, 52" floating deck, Kohler 15hp, pull start). It had less than 300 hrs on the meter & was in good condition. The only mowing I do with it is our church property...about 5 acres. Toward the end of the first season, the blades failed to engage with the PTO switch. At that point I got the service manual from Toro & began to learn about the system. The 7.5 amp fuse was blown. Replacements blew immediately. I check the PTO switch as outlined in the service manual. I originally thought the delay module might be the problem due to a slight discoloration on one part of the sealed unit. I found an exact replacement on eBay, but got the same blown fuse. All of this led me to the clutch. The service manual stated a resistance check across the clutch terminals should be between 2.8 & 3.2 ohms, and that a reading outside those parameters indicates a field failure requiring unit replacement. Mine showed 1.8 --> so, I bought a new Ogura clutch from JThomas.com, made the swap (air gap set & burnishing procedure included), & life was good.
Until about 2 weeks ago.
While mowing at the church, the blades disengaged. No biggie. I thought maybe I had let off of the bail switch slightly. Re-engaged & kept going. Then it began to happen several times in a row (which I think had also happened the previous year). Then...nothing.
So, I quit. Checked the fuse, and...yes, it was blown. Did the resistance check across the clutch terminals...oh, no...1.8 ohms.
I have ordered another clutch & am ready to install, but at $200+ each I just want to make sure I'm covering all my bases.
My questions:
(1) How long should a clutch last? (My mower only has about 370 hrs on it how, and it's only been 1 year since replacement.)
(2) Is there something I'm doing/not doing to cause the clutch to fail?
(3) Is there some other part of the system that could be causing the unit to fail?
Thanks in advance for any input/advice.
#2
Fish
Re: Toro / Ogura Electric Clutch
First you need to monitor your voltage readings while running under a load, it might be a charging problem...
Fish has you pointed in the right direction...
If you are over voltage OR getting AC ripple in your DC voltage, it will burn out the clutch coil.
Also if the voltage is Low you can have a light magnetic clamp and the clutch will slip, over a period of time that heat buildup will destroy the clutch & can short out the coil.
So check the voltage and check for AC ripple.... :smile:KennyV
I obviously have to put the new clutch on, but then will immediately do some testing of the electrical system.
This mower has the Kohler Command CV-15 -- simple pull-start, so no battery or starter to consider. So, am I only really concerned about the rectifier/regulator module? Possibly the stator?
#5
Fish
Re: Toro / Ogura Electric Clutch
Wow. I cannot remember ever working on a pull start engine with electric clutch and no battery/starter. A battery in the system would fill in the rough edges a bit....
First off, give all of the mower's and engine's model and spec numbers, plus describe the wires in and out of the regulator, color/number/routing etc.
Mower = Toro Model 30292 (Proline Hydro walk behind)
Engine = 15hp Kohler Command Pro (CV15)
3 wires from rectifier: "AC" on either side are White & run to the flywheel/stator..."B+" in the middle is Black (becomes Violet at the first connector) & runs to the ignition key switch
I installed the new clutch but have not connected it yet. Fired up the mower & took the following readings:
Across the rectifier ("AC" to "AC") = 49 vac
GND to center of rectifier ("B+") = 37 vdc
Those readings seem way high.
Across the pins that would normally feed the clutch = jumps to a whopping 21.5 vdc when I engage the PTO switch
Again...pretty high!
#7
Fish
Re: Toro / Ogura Electric Clutch
Kohler states that the 2 stator/white wires should be at least 28ac, so I would have to vote on the regulator burning up your stuff, but let me dig out some manuals before you buy one. There are some Kohler guys here that should chime in hopefully.
No battery, no load voltages will be high. If you can, plug in your new clutch to the harness by itself, run the engine at WOT, turn on the PTO switch. The clutch will engage and this will give you a load on the charging system so you can check for actual load voltage from the charging system.
While I understand that the operating voltage under load might be lower, I'm pretty hesitant to use the new clutch as a testing device.
Surely there would be some non-load specs for the rectifier/regulator...or perhaps some other testing I can do on it. The Kohler manual shows a tester for that under "Special Tools". Of course, I don't have that...but at least it is possible to do.
I used a dc fan I found in the garage. Not sure what the rating was, but my Toro fuse blew right away anyhow. None of the lawn/farm dealers in my area carry the rectifier in stock -- they were going to have to order one to the tune of about $70. No thanks...I ordered one myself for around $20. We'll see what the readings are once it's here & installed.
