OT- Electric clutch engineering on mower

Need opinions and engineering help.

So I bought a commercial mower, 60 inch front deck, and a mechanical
PTO. The PTO shaft is driven off the engine crankshaft with a 3 groove
"B" size belt, the kind that has the top covering that connects all 3 belts
and is one piece. Essentially it's similar to 3 separate B size belts.

Anyway, to explain the current arrangement:
This mechanical PTO consists of a PTO shaft inside a tube with
roller bearings on each end. The rear of it has a 7.5 inch 3 groove pulley and up toward the front of the tractor is a U joint and open shaft to connect to the mower deck. There are two lower pivot bushings on this tube, so the tube can move closer and away from the engine pulley. A couple control rods and an bell crank work to move the tube, and then lock 'over-center' when engaged to keep the belt tight between the pulleys.
There is a brake bracket that has a piece of brake lining on it (a block) so when the shaft moves toward the crank pulley (belt slack) the PTO pulley rubs this block and it is 'supposed' to act as a brake....it does not
The PTO shaft spins a bit all the time.

The pulley end of the PTO shaft, has the bushing. It's worn out of its mind
and most of the movement is taken up, not tightening the belt, but taking up slop in the bushing.
I had to take it all apart to get the shaft out, and even had to remove the engine to get access.

I'm thinking this arrangement is flawed by design, and now am leaning toward an electric clutch-brake like most mowers have.
My main concern is space to retrofit the C-B unit, and sizing it to handle the load. I plan to call Ongura and get help with sizing.

The unknown:
Problem is, the engine is a 32HP diesel, aprox 46ft/lb of torque.
It now has the 3 B size belt pulleys on it. Most of the Ongura clutches are
2 B grooves at best. I found a belt HP rating chart, and it seems to show that each B size belt is capable of only around 9-10HP at 3600RPM. Are these published numbers very conservative ratings for the belt HP ratings? It seems in mower or Agricultural applications, they always use belts way beyond what rating tables show as max.
I'm leery about only 2 belts, as there are now 3, and it is a major project to change the belts. Maybe 2 or 3 separate belts could be changed in place, but surely the 3 groove belt that has the top joining covering, would require major wrenching to get the new one in place.

I want to fix this thing ONCE, and do it right. I'm too far in to just fix the bushing and hope the brake setup will work as designed. I don't think it ever did.

dk

dkmc said:

Need opinions and engineering help.

So I bought a commercial mower............................
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I want to fix this thing ONCE, and do it right. I'm too far in to just fix the bushing and hope the brake setup will work as designed. I don't think it ever did.

dk

Click to expand...

Umm.... maybe the FACTORY that built it has a retrofit kit?
Or.... just rapair it, and go on mowing...

Or..... pay an ingineer to help you? or maybe just a shade tree guy... think of the liability someone else would have if this contraption really hurts someone ... I wouldnt touch it with a ...
You get the idea...

If you want to go to the trouble to fix it permanently, replace the mechanical drive with hydraulic. That's what a lot of the newer machines have gone to.
Tom

The ferris 5000 series ran (runs) a cat diesel (perkins in reality) . It was 33 hp, put out over 55ft. lbs of torque, had the big 3 series ogura and ran a two belt setup.

The banded belts may be more difficult to change but they will carry more power and last longer. The belts that are banded are matched in length so you don't wind up with the shortest belt doing all the work.

robmc said:

The ferris 5000 series ran (runs) a cat diesel (perkins in reality) . It was 33 hp, put out over 55ft. lbs of torque, had the big 3 series ogura and ran a two belt setup.

Click to expand...

This is the type of info I seek. My engine is a Yanmar.
Then again, maybe the belts on the ferris are much easier to change......
The larger Ongura clutches have a 2 groove pulley and they are rated for 250ft/lbs static torque. Real curious what a B section belt is capable of horsepower wise. Of course with a life of several hundred hours not minutes...

Most "Commercial" Zero Turn Mowers use a vertical shaft engine with a single B series belt. I have sold up to 27 hp Kohler powered 72" cut Husqvarnas, and they use a Warner Electric Clutch and single B style belt. Never had a problem with those at all.
Everride (now Ariens) made a 25hp with a 60", and the factory recommended engagement for the electric clutch was FULL throttle. No problems there, and that was a B113 kevlar belt.
IMHO a dual drive should be more than enough, matched or banded would make it better.
Check out the Warner clutch line - lots of aftermarket companies carry them for OEM fitment. Ogura was used alot by John Deere, and they are pretty much OEM only.

From your description you say the PTO shaft has roller bearings, but then it seems to have a bushing. Or is the bushing part of the tightening mechanism? Has the PTO shaft "run on" for a long period, or did it just start? If it has been dragging on for a long time, it could be due to missing or misaligned belt guide(s).
When a Manual system is disengaged, it needs guides to hold the belt close to the pulley on the sides so the belt becomes "longer" and doesn't drag. If they are missing or not adjusted properly, the belt tries to make a circle instead, which causes it to drag on the far end of each pulley in the pulley groove.

bob

I think most of the solution to your problem lies in the end of Bob's response. If a tight/slack belt arrangement does not have the proper blade guides, it will not disengage properly. This is all the more so when you are wasting travel due to a worn pivot.

The drive arrangement you describe actually sounds pretty elegant - simple and (should be) effective. I would never go to all of the bother and expense to try to rig up an electric clutch that may or may not work well. It's much simpler and sure-fire to rebuild the existing system, perhaps with stouter bushings or bearings to pivot the PTO shaft on. If a prior owner has removed the belt guides, they're not too complicated or hard to replicate. Remember that these are a key part of the system and that it's unlikely to work properly without them. If this is a well-known brand of mower and there is a dealer nearby, perhaps you can buy any missing belt guides or get some idea what they look like so that you can duplicate them.

Steve

Great info Bob, thanks.
The PTO shaft runs in a tube on roller bearings, both ends.
Tube pivots closer (dis-engaged) and farther away (engaged) from
crankshaft centerline.

You say you 'sold'.....salesman?
Owner of a mower business?
Still do or not any more?

Don't understand the full throttle engagement, usually they
say just off-idle to engage or shut down.
I'll checkout Warner as well.

When a Manual system is disengaged, it needs guides to hold the belt close to the pulley on the sides so the belt becomes "longer" and doesn't drag. If they are missing or not adjusted properly, the belt tries to make a circle instead, which causes it to drag on the far end of each pulley in the pulley groove.

Click to expand...

There are guides, and what you explain could be happening.
Wait....I just went and looked at something.
There is a small plate on the lower frame with 2 5/16 bolts in it.
I wondered about it, does nothing....
Now I looked in the manual at the exploded view.....they call that plate (which is shown much longer in the picture) .....'lower belt guide'!
I looked at it again.....its broke off!
The upped belt guide was not even near the belt, it was up away from it about 3/4". Of course the belt was 'making a circle'!

EDIT: I think I feel that 'boy do I feel stupid' feeling about to come on.....

sa100 said:

I think most of the solution to your problem lies in the end of Bob's response. If a tight/slack belt arrangement does not have the proper blade guides, it will not disengage properly. This is all the more so when you are wasting travel due to a worn pivot.

The drive arrangement you describe actually sounds pretty elegant - simple and (should be) effective. I would never go to all of the bother and expense to try to rig up an electric clutch that may or may not work well. It's much simpler and sure-fire to rebuild the existing system, perhaps with stouter bushings or bearings to pivot the PTO shaft on. If a prior owner has removed the belt guides, they're not too complicated or hard to replicate. Remember that these are a key part of the system and that it's unlikely to work properly without them. If this is a well-known brand of mower and there is a dealer nearby, perhaps you can buy any missing belt guides or get some idea what they look like so that you can duplicate them.

Steve

Click to expand...

And suddenly........it begins to look like you are 100% correct.
Just what I'm thinking too.
This mower is long obsolete, it's a Howard Price Turf Blazer.
I'll likely get flamed by people saying they were a POS.
The broke off lower guide is not hard to duplicate at all.

What really worries me now, is I have 5 hours of pit-stop type frenzy work turning this thing into a 'kit'. I had to get it apart anyway to deal with that worn bushing on the PTO tube pivot. It scares me to think of putting it all back together, (probably 10 hours of more fast-paced work), fit a new lower blade guide, new belt, and adjust upper guide correctly, and then it still doesn't disengage fully. The 'brake block' only rubs on the OD of the PTO pulley, on the small flats between the grooves, and they are worn to sharp edges.
If I have to go back to the Electric clutch brake retrofit, I'll have to take it allll apart again......

I am 3rd generation family business. My grand father started it as a welding shop/car repair/machine work. Welcome to Paine's Garage Online!

The full speed engagement was new to me as well. The reasoning I was told was to prevent slippage of the clutch - engineers found that lower speeds allowed the clutch to slip for a longer period. Sounds odd to me too.

As my father always says (no offense to engineers) the old stuff worked well because it was designed by farmers (or farmers sons) and it was solid. New stuff is by the book learned - just not the same.

If it lasted this long under commercial use, the original design was probably a good one.

Good Luck

Bob11x wrote, "As my father always says (no offense to engineers) the old stuff worked well because it was designed by farmers (or farmers sons) and it was solid. New stuff is by the book learned - just not the same."

I think the difference between then and now is that "then" things were design driven while "now" it is cost driven with no regard for durability or repairability -- the bean counters are winning while the man on the street suffers.

I think the difference between then and now is that "then" things were design driven while "now" it is cost driven with no regard for durability or repairability -- the bean counters are winning while the man on the street suffers.[/QUOTE]

Yes, that does seem to be the case - thank you for stating it much clearer than I did. Better to put the blame where it should be

Bob, George, et al,

Your theory over simplifies things. In the psst things were built well for a variety of reasons, few or any having to do with farmers.

People were raised to take pride in their work and do their best. They believed that their products would be a lasting testament to their ingenuity and integrity.

Engineers at that time did not have all of the computer-aided tools at their disposal to determine the optimum balance of strength vs. economy. Materials were cheap, and reputations were precious. So, build it extra-tough and all would be well.

Obsolescence was not something to consider in those years. It was thought that what was a good and profitable machine then would be a good and profitable machine in 100 years. Today, stuff that is 10 years old is hoary and ancient.

There are downsides to this, as well. This drive for quality may have contributed to the demise of many great companies. Think about it. If you are a lathe builder, and you build a lathe that will work reliably for 100 years, you have effectively deprived the market of one future sale. This is fine so long as the economy is growing and there is an ever-increasing need for lathes. But as soon as things slow down, expect trouble. Oh, there will be some sales as machines are wrecked, but nothing like what is needed to sustain manufacturers.

I always wonder if today's manufacturers consider this in their planning. Something tells me they aren't that smart. Plus, the fast pace of technological advancement renders the point moot, to a large extent. Bottom line, machines are built to a price point and to last as long as it's anticipated the machines will be productive and profitable.

It's simpler in the consumer arena. Customers have signaled they want CHEAP, and it's cheap they get.

Back to the matter at hand, DKMC, as you are well aware, being able to stop a mower blade reliably and repeatably is a key safety factor for any mower. If that mower lacked this key feature when it left the factory, the company would have been sued out of existence long ago, and their products recalled. I think all of the ingredients are there for a good mower. All you have to do is restore them. Having the manual is an extra benefit, allowing you to duplicate the missing or broken parts with accuracy.

You cite the time it will take to rebuild the mower. But how much longer will it take to refit an electric clutch? And don't neglect the cost of the clutch. And when you are done, you are no more certain that the result will be satisfying than you will be should you rebuild the original design - less so, in fact, because it's a safe assumption that the original design did work well at one time, and it managed to last long enough to wear out several parts. You don't have that reassurance with the electric clutch!

Steve

Was just doing some reading on my own, regarding electric clutches. I was not aware of the sugested break in period recomended for electric clutches, Something like a hundred off and on cycles[no load], befor applying a load. [RED BOOK] [BAUM BEARING CO.].
Surplus Center, Lincoln NE. Has several types of electric clutches available also. They would have to be a lot cheaper than OEM parts. dave [acme thread]

The clutches from the surplus center are what I was considering.
Now I'm thinking of putting it back together with new belts and
belt guides in place correctly.
The manual says the blades must stop in 7 seconds.
I guess it would also be easier to fit some sort of solenoid activated brake
that pushes on the face of the pto pulley. More contact surface.....

In my defense, I just got this thing, and it has all the little signs of being 'worked' on (or over)
by wanna be mechanics. So this is typical sorting out of problems and hopefully should calm down after this initial thrash session to get the little details corrected.

Bob11x
I go thru waterloo lots of times.
I have gotten parts for my Woods mow'n machine (same as a grasshopper) zero turn mower from Martins in Romulus.
Thanks for your key info and insight!

dk

PS 11X sounds like a number for a dirt modified.....?
Wait a minute.....Pains garage.....there are Pain's that do race dirt I believe.
Steve Pain?

Howard Price........ been around along time. Not a POS, That Turf Blazer is built like a brick---- house in many respects. The Toro Groundsmaster was similar to what you describe, ran a two belt joined setup, a pita to change the belts, but having said that if I were you I would rebuild to original specs. Me....I'm crazy enough to try to reengineer it. The newer ones are running hydraulic motors on the decks. The problem with new stuff is the hydrostatic drives are a super idea along with a ton of other stuff, but to meet a price point they don't overbuild like yrs. ago and then you start having problems.
I use to go to Oswego to see the super modifieds run..... They are brutal. From Lebanon Valley to Syracuse and everywhere in between..., you've got a ton of dirt tracks in N.Y. state.

Well, first things first......I really like Oswego speedway!
Went several times this summer


Howard Price co is mostly long gone.
I called the place that bought them out.
The can supply parts, but it sounds low volume and high priced.
I'll make my own stuff.

On the turf care websites there is some mention of them, and I think
the cowboys that abuse them in commercial mowing situations, and
do their half-assed repairs on them are the ones that say POS.
I only have 2-3 acres I mow, I will use the machine myself, and also
the snow blade to do the driveway.
Usually every machine that's a deal, has the standard level of mis-guided
repairs and cob job work done to it that needs to be fixed.

I just wish I asked this question here and let it float awhile before I
did the real-life exploded view of the mower in the driveway......
I could have experimented with the belt guides first.
Oh well, that damn bushing does need replacing....

i have both belt slack and electric clutch.they both have the high and low points.there is no doubt you could make an electric work,but it would be far more time and cost effective to repair / rebuild your existing setup.as far as the 3B setup,our grasshopper with a 72" deck and 20 hp kubota has no issues with the dual belt setup.the three grasshoppers average 100 hours mowing a year.i have replaced two drive belts on only one mower in three seasons working there.

DK,

Yes, Steve Paine is my brother. There are a lot of Dirt tracks in NY, but unfortunately the organization known as D.I.R.T was bought out 4 years ago, and has done everything possible to ruin racing. I don't think it is malicious, just ineptitude - bad decisions, lack of leadership, etc. It is a shame - I actually enjoyed the racing back in the 70's + 80's. By the 90's it started to become a "business", and a lot of the family attraction was lost.
I haven't been to a race in 3 years. I miss the people, the sound, the excitement, but I don't miss the politics + BS.

Stop by next time you drive thru.

bob