Belly mower does a ragged job - why?

[bigtiller]

Several of us are reading directions written by people with poor English skills and not involved in the logic of what they are saying. It is 100% obvious that you can minimize the wear/tear/jerk by engaging the mower at a low rpm before revving it up. Duh ! The manual saying to "engage" at full throttle needs to be rewritten to say "operate at full throttle" not "engage at full thorttle."

This screen shot of a jd 425/445 manual is pretty clear. Start pto with wot.

 

[KennyG]

This screen shot of a jd 425/445 manual is pretty clear. Start pto with wot.



View attachment 710037

That's very interesting. I would think the PTO engagement system on a 4xx machine would be similar to my 2320. My manual specifically says to keep engine speed below 1500 rpm and engage the PTO, then bring up to operating speed.

 

[K5lwq]

That's very interesting. I would think the PTO engagement system on a 4xx machine would be similar to my 2320. My manual specifically says to keep engine speed below 1500 rpm and engage the PTO, then bring up to operating speed.

And this is what I would do regardless what the manual says.

 

[bigtiller]

And this is what I would do regardless what the manual says.

That's very interesting. I would think the PTO engagement system on a 4xx machine would be similar to my 2320. My manual specifically says to keep engine speed below 1500 rpm and engage the PTO, then bring up to operating speed.

I had a few 425/445's. They are gas engines. If they were not warmed up long enough and WOT, the engine would die when a 54" deck was started. After mowing for 5 + minutes the deck could be started at a slightly faster than idle speed.

The same series 455 was a diesel and it would start the deck at a cold idle.

 

[Williy]

IMHO I believe the sudden shock of full throttle
would cause excessive wear on components for
early failure so dealers can make more money???

For me will idle then turn on pto and slowly increase
rpm's until 2600 is reached then start cutting.

willy

 

[sunandsand]

Blades are out being sharpened and balanced now (Wednesday). Expect them back in a few days.

The grass isn't much over 5 to 6" tops, a few longer stragglers.

Problem is that I work (inside) during the day and can't get out to mow until early evening, and we've had thunderstorms on a daily basis. Can't mow wet grass. Once it dries out, I may take the good advice of doing it in two passes. We'll see.

As I say, "the plan" is to replace the newly sharpened blades, rev the sucker up, and go slowly. I'll report in as I progress.

PTO is engaged at idle, although it can be disengaged at higher RPMs.

I really did like the expression "as sharp as a banana". Delightful and descriptive. Gotta be careful though, them's fighting words!

Best Regards,

Mike/Florida

 

[sunandsand]

OK, blades came back after a couple of delays, the guy didn't have a grinder healthy enough for tractor blades, he usually does riding mower stuff, so he had to send it out. Then he was out of town for a few days.

Picked them up yesterday evening, had a ground breaking to to go (much more fun than putting the blades on the belly mower, better food, too).

Assembled it today, 80 ft lbs on the mounting nuts, discovered that the drive shaft from the front PTO to the belly mower gearbox only goes back together ONE way, there is a blocked spline in the sliding joint so the orientation has to be correct. It looked like a burr, but when I took it outside into better light, aha, it is keyed!

Discovered FOUR grease fittings not in the manual, gave 'em each a shot as well as the ones in the manual.
(Three spindles, one tension lever, one on the bottom of the gearbox, one on each U-joiont at each end of the drive shaft, and one at the sliding spline in the middle. Manual only says four - spindles and sliding spline, I found eight. I now wonder how many "stealth" grease fittings there are hidden on the tractor?)

Put it all together, fired it up, warmed it up, set height to 3.0 inches, engage belly mower, mid range speed, revved it up and, CHARGE!!!!

Does a WONDERFUL job! Dear Bride even remarked on it - says it looks really good.

So the moral of the story is:

1) Use SHARP blades (preferably much sharper than a banana, or so I'm told ;-)

2) Crank it up to 2600 rpm

3) Go slow

4) Always check with the peeps on TBN if you have a question, they have a LOT more experience than I do!

Thank you everyone and best regards,

Mike/Florida (with the manicured lawn!)

 

[Slowpoke Slim]

Nice.

Thanks for the follow up.

 

[LD48750]

Mike... at what RPM is the tach marked for the PTO?

The picture back a frw posts indicate 2800 is the recommended setting, not 2600.

 

[big bubba]

you've already expended considerable energy & time on this. get new blades installed, have existing sharpened & swap out occasionally. only way to tell if problem is blade related. don't understand the hesitation to replace
that would have been my 1st move on this whole progression
good luck

 

[sunandsand]

you've already expended considerable energy & time on this. get new blades installed, have existing sharpened & swap out occasionally. only way to tell if problem is blade related. don't understand the hesitation to replace
that would have been my 1st move on this whole progression
good luck

You are quite correct. It simply didn't occur to me that the blades would be so dull after 75 hours or so of mowing grass. These are the original blades, so I didn't really have a good idea of how long I could expect them to stay usable.

Now I do. I'm ordering a set of new blades and will put them on the shelf. In 50 hours or so of mowing time, I'll see if I need to swap them out, and if so, I will do it. As you say NEXT TIME, my first stop will be to look at the blades.

Best Regards,

Mike/Florida

 

[sunandsand]

Mike... at what RPM is the tach marked for the PTO?

The picture back a frw posts indicate 2800 is the recommended setting, not 2600.

Tach on my B2601 isn't marked for optimum PTO speeds. Red line is about 2,800.

Manual says rear PTO turns 540 RPM when engine is doing 2,768 RPM.

Mid PTO turns 2,500 RPM when engine turns 2,753 RPM.

That tells me the sweet spot is 2,750 to 2,770 RPM.

Translation - For best results, pour on the coal and let 'er rip!

Best Regards,

Mike/Florida

 

[sandman2234]

I love it when a plan comes together! (somebody else said that, I just quoted it).
David from jax

 

[Midniteoyl]

How long did it take you to put on them 75 mowing hours?

 

[big bubba]

You are quite correct. It simply didn't occur to me that the blades would be so dull after 75 hours or so of mowing grass. These are the original blades, so I didn't really have a good idea of how long I could expect them to stay usable.

Now I do. I'm ordering a set of new blades and will put them on the shelf. In 50 hours or so of mowing time, I'll see if I need to swap them out, and if so, I will do it. As you say NEXT TIME, my first stop will be to look at the blades.

Best Regards,

Mike/Florida

please don't assume i am an expert in those regards...i usually learn the hard way then adjust
only suggestion is to be safe under the deck when removing blades, etc. i prefer timber blocks to jack stands.
i've done it a few times in my youth, but would never recommend crawling under & sharpening blades attached.
just to state obvious, sorry

 

[4570Man]

You are quite correct. It simply didn't occur to me that the blades would be so dull after 75 hours or so of mowing grass. These are the original blades, so I didn't really have a good idea of how long I could expect them to stay usable.

Now I do. I'm ordering a set of new blades and will put them on the shelf. In 50 hours or so of mowing time, I'll see if I need to swap them out, and if so, I will do it. As you say NEXT TIME, my first stop will be to look at the blades.

Best Regards,

Mike/Florida

50 hours is still way past optimal sharpness. I’d say more like 20 hours or less.

 

[sandman2234]

50 hours is still way past optimal sharpness. I’d say more like 20 hours or less.

20 hours if you like the comment your bride made when you did it right after the blade change!
David from jax

 

[CH4Ohio]

Tach on my B2601 isn't marked for optimum PTO speeds. Red line is about 2,800.

Manual says rear PTO turns 540 RPM when engine is doing 2,768 RPM.

Mid PTO turns 2,500 RPM when engine turns 2,753 RPM.

That tells me the sweet spot is 2,750 to 2,770 RPM.

Translation - For best results, pour on the coal and let 'er rip!

Best Regards,

Mike/Florida

Glad it's working better.

10-4 on "pour on the coal"!

Every Kubota tach that I've ever seen has a mark showing PTO RPM speed. Yours doesn't look like this?

 

[sunandsand]

Glad it's working better.

10-4 on "pour on the coal"!

Every Kubota tach that I've ever seen has a mark showing PTO RPM speed. Yours doesn't look like this?

View attachment 711684

Yes, it has a little red square at 2,800 rpm.

On every other vehicle of the many, many vehicles I have ever owned equipped with a tachometer, the red line/red mark is the top allowable RPM for the engine. I'm talking cars, motorcycles, airplanes, boats, exceed red line and you'll blow it up.

I went and looked through the Kubota manual and I didn't SEE a red line! (I may have missed it, or it may not be possible to get there under load.)

In any event, 2,800 rpm seems to be the design target speed for the engine. Henceforth, that's where the needle will be and I'll wear my ear protectors (I do anyway).

Best Regards,

Mike/Florida

 

[CH4Ohio]

Understood. But it's not like a car or motorcycle. You can't red-line or over-rev the engine by running it at WOT. Like a motorboat, chainsaw, lawn mower, snowblower, etc., it's designed to run at WOT.

Thanks for the follow-up info. Happy mowing!