Mow Using 960 PTO Setting?

[bp fick]

The operator's manual is kind of sketchy, so here goes a question for those more familiar with the 960 pto setting on Kubota's B series tractors.

Rather than using the more typical 540 setting, what is to be gained, if anything, or avoided, if anything in using the 960 pto setting? Benefits? Concerns? Things to do or not do?

It's new to me.

 

[beenthere]

That will most likely depend on what attachment you are running at nearly twice the rpm. Many are designed in their gear boxes to run the standard 540 PTO rpm.

Or is there something in the question that I'm missing. Is it maybe mid PTO or rear?

 

[repete]

If you mow w/your engine at 2000 rpm in the 540 position it is rotating at 1080 rpm

If you mow at 1000 rpm in the 960 rpm range then it is rotating at 960 rpm.

Kind of depends on whether you need the power you would get at 2000 rpm as opposed to 1000 rpm.

 

[OrangeRidge]

Is this your engine profile BP ?

http://www.engine.kubota.ne.jp/english/catalog2/pdf/07_d1005_30.pdf It's more about labouring than output really . The only guy I
know around here who uses 960 , has a water pump attached for
ocassional lawn irrigation from a dam. He won't be using that for
a while ; 17" of rain this weekend !

 

[bp fick]

If one uses the tractor's 960 pto selection, attached to an RFM or brush hog, in order to reduce engine RPM to 1900-2000, but maintain mow blade speed, is this a good idea?

I know it done, but what are the perceived benefits or potential problems in doing this.

 

[bp fick]

Is this your engine profile BP ?

http://www.engine.kubota.ne.jp/english/catalog2/pdf/07_d1005_30.pdf

O.R. -Yes, it is.

 

[bp fick]

If you mow w/your engine at 2000 rpm in the 540 position it is rotating at 1080 rpm

If you mow at 1000 rpm in the 960 rpm range then it is rotating at 960 rpm.

Kind of depends on whether you need the power you would get at 2000 rpm as opposed to 1000 rpm.

Repete: Thanks for the info. It spawns some questions so I can understand better.

This would be a RFM, pulled through very, very thin grass. There is no strain on the mower at all. My tractor's tac marks PTO speed for the 540 at 2700 rpm. Is 1800 engine rpm, using the 960 PTO producing approximately the same mower speed? If I understand the math, the mower is spun much too fast.

Question - is it slogging the engine? Would it be unwise or perfectly acceptable?

 

[repete]

To be honest I never mow in 540 speed. I usually run with the engine speed at probably 1300 rpm or so. Always the higher speed. That is the only tool I run on high speed though. Post hole auger, tiller, fertilizer spreader and everything else at 540. But I have 30 HP.

 

[bp fick]

repete thanks. Are you concerned about lugging the engine at that speed or are you happy with it?

 

[repete]

I really let the engine tell me. If it is sounding good, staying cool and clear exhaust then I think I am doing fine. I have been running it that way for hundreds of hours. I do on occasions change the gearbox grease and daily grease the u joints. Overkill on the grease but it mostly gives me a chance to make sure the input shaft going into the gearbox is clear of any buildup of grass that may take out the seal. I run a 60" deck.

 

[Chilly807]

BP,

If I were guessing, which I'm not, I'd think you're trying to get through the break-in period without running at steady full speed with little load. If that's the case, then I understand where you're coming from. Mowing is tough on a new engine, in that it limits your speed to a constant steady rate, instead of varying speed and load as most recommend.

Having said that, I bush-hogged about 20 acres with my L3400 with about 20 hours on the clock. It had to get done, and it was the only tractor I had to do it with. I did try to vary the rpm a bit, between 1800 and 2400 (my 540 PTO speed is about 2350). Also, stopping and backing up for corners, I dropped the rpm for a few seconds, then continued. Letting the engine idle for a minute after every ten minutes of mowing might not be a bad idea either in your case.

I did make sure that when I went through heavier grass that the rpm was close to where it was supposed to be to avoid lugging the engine.

If it were me, I'd run the PTO at the correct speed and vary the engine rpm a bit, rather than use the 960 setting. I assume the mower calls for 540? If so, overdriving it won't help the cause, though it will undoubtedly do a great job of cutting the grass. Running the engine speed lower to get the correct PTO speed won't do the engine any favours either, but as long as it's not lugged it shouldn't hurt it. How much more does it labour starting the mower at 960 than 540?

Sean

 

[bp fick]

Sean,

Actually, got three or four neighbors who do light brush hogging using the faster PTO speed to keep the engine RPMs down. They all claim they like the lowered noise, and see no need to do anything different. Some claim to have done this for hundreds of hours.

I honestly don't mind running at 2600 or 2700 which would run the RFM. Again, this is very thin grass on the lawn. We don't have thick grasses on the sand base up here.

I just thought I'd try it. I mowed some at 540 setting with engine at 2700 and some at 960 with engine at 1700. Yeah, it's nicer with the engine not roaring. I had no sense that the engine was lugging at 1700, but again, this is new to me. Never even had the option before.

 

[Transit]

BP,

If I were guessing, which I'm not, I'd think you're trying to get through the break-in period without running at steady full speed with little load. If that's the case, then I understand where you're coming from. Mowing is tough on a new engine, in that it limits your speed to a constant steady rate, instead of varying speed and load as most recommend.

Having said that, I bush-hogged about 20 acres with my L3400 with about 20 hours on the clock. It had to get done, and it was the only tractor I had to do it with. I did try to vary the rpm a bit, between 1800 and 2400 (my 540 PTO speed is about 2350). Also, stopping and backing up for corners, I dropped the rpm for a few seconds, then continued. Letting the engine idle for a minute after every ten minutes of mowing might not be a bad idea either in your case.

I did make sure that when I went through heavier grass that the rpm was close to where it was supposed to be to avoid lugging the engine.

If it were me, I'd run the PTO at the correct speed and vary the engine rpm a bit, rather than use the 960 setting. I assume the mower calls for 540? If so, overdriving it won't help the cause, though it will undoubtedly do a great job of cutting the grass. Running the engine speed lower to get the correct PTO speed won't do the engine any favours either, but as long as it's not lugged it shouldn't hurt it. How much more does it labour starting the mower at 960 than 540?

Sean

Cutting light grass at low rpm may be ok, but if the PTO is running faster than 540 you are asking for trouble. The stored energy is proportional to the square of the speed, double the PTO speed and energy goes up 4 x normal, a bit hard on the gear box, devastating on the blade bolts and blades. You risk launching a blade at 100 mph across a field to say nothing of the out of balance hog.

 

[DonnieP]

I run high speed on PTO selector a lot of the time while mowing light stuff and even on the snow blower if the snow is light. My math: 540/960 = 0.5625 2700 x 0.5625 = 1518 rpm will give you 540 rpm at the mower using the 960 rpm selection. It's much easier on fuel, easier on the ears, you're not hurting the mower, you're running it at the correct speed, and if you listen to the tractor, and watch the signs like repete says, you can tell when the load gets heavy, change pto range and rev her up

 

[kuboman]

Sean,

Actually, got three or four neighbors who do light brush hogging using the faster PTO speed to keep the engine RPMs down. They all claim they like the lowered noise, and see no need to do anything different. Some claim to have done this for hundreds of hours.

I honestly don't mind running at 2600 or 2700 which would run the RFM. Again, this is very thin grass on the lawn. We don't have thick grasses on the sand base up here.

I just thought I'd try it. I mowed some at 540 setting with engine at 2700 and some at 960 with engine at 1700. Yeah, it's nicer with the engine not roaring. I had no sense that the engine was lugging at 1700, but again, this is new to me. Never even had the option before.

To maintain 540 rpm requires a slow engine rpm usually below the recommended rpm for proper engine operation under any kind of load. Also you run the risk of accidentally overspeeding and doing serious damage to your implement. Just my 2bits