Belly mower does a ragged job - why?

[ruffdog]

Wow....500 less engine RPM than what it was designed for is a huge drop in mower blade tip speed.

 

[nyone]

Wow....500 less engine RPM than what it was designed for is a huge drop in mower blade tip speed.

Since the belly pto operates over 2000rpm a 500rpm drop could mean 1000rpm less blade tip speed.

 

[4570Man]

I can visualize putting the mower blades on upside down by mistake, but how do you put one on backwards?

Wouldn't it either be "right side up", or "upside down"?

You can’t put them on backwards unless you bought pretty rare left hand turn blades and put them on a right hand mower.

 

[sunandsand]

OK, took the belly mower off the tractor, put a couple of chains on it and lifted it vertical so I could get at it using the FEL. (Safety blocked as well, it weighs 300 lbs.)

No crud accumulated under the deck.

Belt appears OK, not glazed or cracked.

Blades installed by dealer or factory so they are right side up, but see below. (Note that dealer setup was "indifferent", I've had to correct a few things here and there. That's what I get for reading instructions and manuals.)

Blades not bent, but VERY, VERY dull, these desperately need to be sharpened.

There's a flat metal plate bolted to the leading edge of the deck, one on the left side, there are holes in the deck for one on the right (discharge side). The left one is present, the right one appears to never have been installed. The plates extend back horizontally from the lip on the deck back perhaps an inch on the left side, no idea on the right side because it just isn't there and I've never seen it.

No marks showing if it was torn off or fell off, paint is undisturbed. I *know* if it came off while I was mowing, it would have made a heck of a racket, in fact, the equivalent plate on my riding mower HAS come off (twice, vibrated apart) and stopped the mower dead each time.


So here's the plan:

1) sharpen and balance the blades

2) determine if the baffle plate is missing, if so, buy and replace (with hardware, three carriage bolts and nuts)

3) clean everything, inspect everything, lube everything. Easy when it is off the tractor, not so easy when it is on.

3) run at higher tach speeds, probably 2,300 or so. (I have to adjust the throttle friction washer, the RPM likes to slowly drop to about 2,000 to 2,100 RPM if I don't hold the throttle open.)


This will probably happen this coming week, so stay tuned!

Best Regards,

Mike/Florida

 

[4570Man]

Your blades probably need chunked and get new ones if they’ve been ran 70 hours without maintenance especially in Florida.

 

[sunandsand]

I'll let the sharpener guy look at them in the next day or so. If I need new blades, I'll get them. No biggie.

I did look at the parts book for the RCK54 mower - there doesn't appear to be the right side guide plate/baffle plate as on the left side. I'll check with the dealer Tuesday.

Best Regards,

Mike/Florida

 

[Have tractor did travel]

Every mower I've ever had except for REAR PTO driven mowers has been run at WIDE OPEN THROTTLE.

Push mowers, cheap riding mowers, tractors with belly mowers -- always run wide open.

Does anyone have a push mower that they don't run at WOT? Why would a belly mower be any different?

My RC72-27B (72") mower cuts really slick running at WOT. It would do a lousy / ragged job at 2100 RPMs.

Deere makes marine diesel engines (stay with me folks, you'll see the tie in to tractors). They rate those engines in 5 gradients, using a rating system of M1 to M5:"

M Rating	Typical Load Factor	Typical Annual Useage	Typical Full Power Operation
M5	≤ 35%	≤ 300 hr	0.5 of each 8 hr
M4	≤ 40%	≤ 800 hr	1 of each 12 hr
M3	≤ 50%	≤ 2000 hr	4 of each 12 hr
M2	≤ 65%	≤ 3000 hr	16 of each 24 hr
M1	> 65%	> 3000	Uninterrupted

In this system, M5 points to engines for recreational cruising boats. The manufacturer is telling us that the M5-rated engines will maximize longevity when those three parameters are met."
Absent particulars from the tractor engine manufacturer, I'd be hesitant to subject my CUT, or SCUT to "full power operation" any more than 25% of the time.

 

[4570Man]

Deere makes marine diesel engines (stay with me folks, you'll see the tie in to tractors). They rate those engines in 5 gradients, using a rating system of M1 to M5:"

M Rating	Typical Load Factor	Typical Annual Useage	Typical Full Power Operation
M5	≤ 35%	≤ 300 hr	0.5 of each 8 hr
M4	≤ 40%	≤ 800 hr	1 of each 12 hr
M3	≤ 50%	≤ 2000 hr	4 of each 12 hr
M2	≤ 65%	≤ 3000 hr	16 of each 24 hr
M1	> 65%	> 3000	Uninterrupted

In this system, M5 points to engines for recreational cruising boats. The manufacturer is telling us that the M5-rated engines will maximize longevity when those three parameters are met."
Absent particulars from the tractor engine manufacturer, I'd be hesitant to subject my CUT, or SCUT to "full power operation" any more than 25% of the time.

WOT and maximum power aren’t the same thing.

 

[Have tractor did travel]

WOT and maximum power aren’t the same thing.

Agreed. But . . . How do you get more power if you're running at WOT ?

 

[Gee Ray]

The sand in Florida is hard on the blades so sharpening them often is a requirement. Also look at the upturned back edge if they are on your blades. This upturned edge will wear quickly and this wear will cause a poor cut. Slow the ground speed of your tractor and as the others have said increase the engine speed.

If you are accustom to a gas engine mower forget the sound worries and run wide open. That is best for your diesel. It does not save much fuel to slow the diesel down and then load it up cutting grass.

You should not be trying to mow with the tractor set in the high range. M should be OK for mowing but L may be needed for heavy mowing.

 

[4570Man]

Agreed. But . . . How do you get more power if you're running at WOT ?

I meant the engine can be running at wot and not be making full power

 

[CH4Ohio]

You can certainly be running at WOT and not be under a full LOAD. In fact, when sitting still and just spinning the blades at WOT, the tractor is under very little load.

I don't understand the reluctance to run the tractor at the proper RPM for PTO work. It's clearly indicated on the tachometer. Based on the manual I downloaded, proper RPM for mowing on that tractor is 2800 RPM. If you were running a tiller or bush hog, the proper RPM would be 2800.

Take it to the dealer and mow some grass in front of their place and ask them what's wrong. I bet $5 they point to the hashmark on the tach and tell you to increase RPMs to 2800.

It's always a good idea to have sharp blades, but it's still not going to cut right at 2300 RPM. That's like taking a basic push mower and running it at 75% of its rated RPM speed. It just won't do a smooth job.
I looked at my Kubota manual for both the rear and mid PTO. For both, Kubota says to run the engine at the speed indicated on the tach. (In my case, that's approx. 2600.) There's no mention of NOT running at WOT and there's also no indication of a "red line" on my tach. WOT on mine is 2800 RPM with NO load on it.

Good luck.

 

[4570Man]

You can certainly be running at WOT and not be under a full load. In fact, when sitting still and just spinning the blades at WOT, the tractor is under very little load.

I don't understand the reluctance to run the tractor at the proper RPM for PTO work. It's clearly indicated on the tachometer. Based on the manual I downloaded, proper RPM for mowing on that tractor is 2800 RPM. If you were running a tiller or bush hog, the proper RPM would be 2800.

Take it to the dealer and mow some grass in front of their place and ask them what's wrong. I bet $5 they point to the hashmark on the tach and tell you to increase RPMs to 2800.

It's always a good idea to have sharp blades, but it's still not going to cut right at 2300 RPM. That's like taking a basic push mower and running it at 75% of its rated RPM speed. It just won't do a smooth job.
I looked at my Kubota manual for both the rear and mid PTO. For both, Kubota says to run the engine at the speed indicated on the tach. (In my case, that's approx. 2600.) There's no mention of NOT running at WOT and there's also no indication of a "red line" on my tach. WOT on mine is 2800 RPM with NO load on it.

Good luck.

It’s pretty common for people to think they’re “saving” the machine by running it slower. How they come to that conclusion I’m not sure.

 

[CH4Ohio]

It’s pretty common for people to think they’re “saving” the machine by running it slower. How they come to that conclusion I’m not sure.

Agreed.

Consider any zero-turn mower, just as an example. Whether gas or diesel, a ZT is going to run at WOT almost all the time. I'd guess that mine runs 95% + of the time at WOT cause I only back it down when I'm getting ready to mow or finishing up and putting it away. For the several hours that I'm mowing, it's all WOT.

There's no tach on mine either. Just bury the throttle and mow. Just like every other lawn mower . . .

Never really gave it a thought till now. Now my head hurts . . . ;-)

Mike -- take it out and mow with it at 2800 RPM for 10 minutes and see if it doesn't do a good job. Even dull blades will cut grass when you spin them at the right speed. They'll tear the grass instead of cutting it clean, but it will be shorter and it will throw the clippings like it's supposed to.

Good luck with it!

 

[4570Man]

Agreed.

Consider any zero-turn mower, just as an example. Whether gas or diesel, a ZT is going to run at WOT almost all the time. I'd guess that mine runs 95% + of the time at WOT cause I only back it down when I'm getting ready to mow or finishing up and putting it away. For the several hours that I'm mowing, it's all WOT.

There's no tach on mine either. Just bury the throttle and mow. Just like every other lawn mower . . .

Never really gave it a thought till now. Now my head hurts . . . ;-)

Mike -- take it out and mow with it at 2800 RPM for 10 minutes and see if it doesn't do a good job. Even dull blades will cut grass when you spin them at the right speed. They'll tear the grass instead of cutting it clean, but it will be shorter and it will throw the clippings like it's supposed to.

Good luck with it!

My ZT is been running at WOT for 2600 hours and still going strong. Pulling the rpms back even a little bit makes the controls more sluggish and the cut quality decreases.

 

[LD1]

Its a mindset I dont think you are ever gonna change. Its laughable to think one buys a tractor and should keep it under 25% service factor...lol

 

[Slowpoke Slim]

OK, took the belly mower off the tractor, put a couple of chains on it and lifted it vertical so I could get at it using the FEL. (Safety blocked as well, it weighs 300 lbs.)

No crud accumulated under the deck.

Belt appears OK, not glazed or cracked.

Blades installed by dealer or factory so they are right side up, but see below. (Note that dealer setup was "indifferent", I've had to correct a few things here and there. That's what I get for reading instructions and manuals.)

Blades not bent, but VERY, VERY dull, these desperately need to be sharpened.

There's a flat metal plate bolted to the leading edge of the deck, one on the left side, there are holes in the deck for one on the right (discharge side). The left one is present, the right one appears to never have been installed. The plates extend back horizontally from the lip on the deck back perhaps an inch on the left side, no idea on the right side because it just isn't there and I've never seen it.

No marks showing if it was torn off or fell off, paint is undisturbed. I *know* if it came off while I was mowing, it would have made a heck of a racket, in fact, the equivalent plate on my riding mower HAS come off (twice, vibrated apart) and stopped the mower dead each time.


So here's the plan:

1) sharpen and balance the blades

2) determine if the baffle plate is missing, if so, buy and replace (with hardware, three carriage bolts and nuts)

3) clean everything, inspect everything, lube everything. Easy when it is off the tractor, not so easy when it is on.

3) run at higher tach speeds, probably 2,300 or so. (I have to adjust the throttle friction washer, the RPM likes to slowly drop to about 2,000 to 2,100 RPM if I don't hold the throttle open.)


This will probably happen this coming week, so stay tuned!

Best Regards,

Mike/Florida

Sharp blades and running it at WOT (2800 in your case), and that mower will cut like it's designed to.

Stop under running your rpms, you're blade speed falls off dramatically, and ANY mower will cut like garbage doing that.

 

[bmg88201]

I have an JD X300 and the owners manual says to run the engine at full throttle when engaging the blades. And that’s what I do, I push the throttle wide open and engage the blades and start mowing. Also, according to my small engine repair guy, he told me that a lot of mowers will get too hot if the rpms are too low for too long cause the engine is not getting enough air.

 

[TMGT]

Agreed. But . . . How do you get more power if you're running at WOT ?

In this case, the D1105 is rated at different engine speeds for various equipment. The highest rpm I've seen the particular engine rated to is 3200. Just because 2800 is the max in this application doesn't mean it's the max engine speed for the engine.

FYI I have 2 other D1105's in commercial mowers that run at 3200 and have over 4k hrs on them so 2800 is not pushing them.

 

[tmajor]

Without reading all of the "back and forths", .... Is the belt on correctly. to spin the blades in the correct direction?