Learning to run a cutter

[terrib972]

I have an old B7100 and recently bought a Land Pride 48" rotary cutter. I'm a widow and have not driven the tractor a lot. I did a couple hours of mowing the other day trying to get used to maneuvering. I'm in north Texas. Ground I was mowing is relatively flat but does have gentle slopes and occasional dips/uneven ground. I was most comfortable with the speed in first gear and the rpm cranked high, slowing down of course for ground irregularities and turns. The PTO was also in first gear. Is this reasonable or should I be working toward using a different gear as I get used to driving? I'm assuming the answer varies for different vegetation growth and ground issues. This is mostly native grass and occasional trees sprouting but the first time it had been cut this year so was very tall. I just wanted to check in to see what I need to know to keep from doing damage to my equipment by running it incorrectly. The Kubota dealer assembled and attached the cutter at its highest setting and I left it there since the grass was so tall, thinking I could lower it for future mowing.

Second question is about mowing spots I need to back into. I wasn't sure if I should stop the PTO and raise the cutter, back in and then start again or if I should back in while running the cutter. Mowing in reverse made me nervous but I wasn't sure if trying to get the PTO started while sitting on tall grass was advisable.

Thank you for your help!

 

[NCL4701]

I have a LOT of trees in the area I mow so I do a lot of backing up while mowing to get under the trees. A rotary cutter should cut in reverse at least about as good as it does going forward.

So far as needing to stop, lift, restart, etc. I don’t know any reason you would need to do that. Just leave it running at the same level your mowing at and back up.

Ground speed and to some degree PTO speed are dependent on quality of cut and your preference. If you’re mowing grass, you’ll probably need PTO speed at whatever max the mower is rated for, which is probably 540rpm for a small rotary mower a B7100 could pull on the 3 point. If you’re mowing heavier saplings or some sort of heavier weeds you might be able to slow the PTO speed some if you don’t want to spray shrapnel quite as hard on a first run through but generally it will work best at rated speed.

If your PTO speed is dropping because you’re bogging down the engine you’ll need to reduce ground speed if you can. If the tractor is maintaining PTO speed, the only things controlling ground speed are quality of cut and your preference. If cut quality is bad, slow down. If you are more comfortable driving slow, drive slow. It ain’t a race unless you’re doing it for a living and your boss is yelling at you.

 

[terrib972]

...

Ground speed and to some degree PTO speed are dependent on quality of cut and your preference. If you’re mowing grass, you’ll probably need PTO speed at whatever max the mower is rated for, which is probably 540rpm for a small rotary mower a B7100 could pull on the 3 point. If you’re mowing heavier saplings or some sort of heavier weeds you might be able to slow the PTO speed some if you don’t want to spray shrapnel quite as hard on a first run through but generally it will work best at rated speed.

If your PTO speed is dropping because you’re bogging down the engine you’ll need to reduce ground speed if you can. If the tractor is maintaining PTO speed, the only things controlling ground speed are quality of cut and your preference. If cut quality is bad, slow down. If you are more comfortable driving slow, drive slow. It ain’t a race unless you’re doing it for a living and your boss is yelling at you.

So here's an ignorant question. How do I know what RPM it's running. Yes the mower is rated to 540 but I'm not seeing a gauge to tell me RPM. Also, is the spin speed on the blades affected by how much "gas" I give it or is that determined by the PTO gear?

 

[i7win7]

Also, is the spin speed on the blades affected by how much "gas" I give it or is that determined by the PTO gear?

TractorData.com Kubota B7100 tractor information

www.tractordata.com

according to tractor data your rear pto has 3 speeds. You need to set it for 540
rpm. On engine tab it's rated at 2800 rpm. Unless owner's manual specs differently (engine at 2800 = 540 at pto)

 

[NCL4701]

So here's an ignorant question. How do I know what RPM it's running. Yes the mower is rated to 540 but I'm not seeing a gauge to tell me RPM. Also, is the spin speed on the blades affected by how much "gas" I give it or is that determined by the PTO gear?

I am not intimately familiar with the model tractor you have, but pretty much every tractor I’ve ever seen has a mark on the tachometer that matches the rated PTO speed. It would be at or near wide open throttle.

If your tractor has a two speed PTO you do need to be sure it’s in the lower speed (540 rather than the higher speed 1000rpm). Most smaller tractors don’t have two speed PTOs but a few do; not sure about yours. Most likely it’s one speed and just on or off.

Yes, engine RPM is directly related to PTO RPM so you have to have the engine RPM at the mark on the tachometer for the PTO to be running at the rated RPM so throttle position is important. There are some large ag tractors that have a separate tach for the PTO but I would be extremely surprised if your machine has a tach for anything other than the engine. While you’re mowing you need to keep an eye on the tach to make sure it’s staying near that mark. If it is running much less, you’re bogging the engine down and need to slow your ground speed. You don’t need to stare at it constantly, though. You can hear the difference in the sound of the engine if it’s bogging down and check the tach to see if it’s slowed enough to be a problem or maintaining speed and just pulling harder.

While engine speed translates to PTO speed, what gear you have the transmission in is totally irrelevant to PTO speed. The engine is running the transmission and PTO but the PTO and transmission are two separate things that have nothing to do with each other.

 

[NCL4701]

TractorData.com Kubota B7100 tractor information

www.tractordata.com

according to tractor data your rear pto has 3 speeds. You need to set it for 540
rpm. On engine tab it's rated at 2800 rpm. Unless owner's manual specs differently (engine at 2800 = 540 at pto)

Didn’t see this post until after I replied. Wow, a three speed PTO. I have no idea what you would use 750 or 1000 rpm for on a tractor that size but there’s a lot of stuff I don’t know. Learn something new every day.

If anyone knows what you’d use the higher PTO speeds for on a small tractor it would be interesting to learn.

 

[i7win7]

If anyone knows what you’d use the higher PTO speeds for on a small tractor it would be interesting to learn.

1000 rpm pto's use a 21 spline shaft terrib972 can buy a 540 to 1000 adapter to run a high speed implement. I don't know what they are, but recognize it by the 21 spline pto.

I can see someone with a pto powered generator switching to the 750 rpm and running tractor at a slower engine speed. Generator gauges will indicate when rpm's are correct

 

[NCL4701]

1000 rpm pto's use a 21 spline shaft terrib972 can buy a 540 to 1000 adapter to run a high speed implement. I don't know what they are, but recognize it by the 21 spline pto.

I can see someone with a pto powered generator switching to the 750 rpm and running tractor at a slower engine speed. Generator gauges will indicate when rpm's are correct

That makes sense for a generator.

Only 21 spline 1000 rpm implements I’m familiar with go with the higher rpm to transfer high HP loads at lower torque to keep from snapping shafts so they seem to be stuff that requires 75hp minimum and often much more. Couldn’t imagine what 1000 rpm implement that’s actually available you could run with a 13 PTO HP tractor but a generator setup does make sense.

Thanks

 

[bucktail]

The multiple speed PTO is designed for the rice paddy tillers. I don't know of anyone who said shifted up and throttled back on their PTO driven generator who is glad they did. Some electronics and motors can be 7sensitive to frequency and doing this makes it harder to maintain. There's a Canadian on here who shifted up and throttled back on his backhoe and said it worked well. It might work on a small auger. A couple members here bought tillers for Jd 400 series tractors. They require 840 PTO so the one with the multi speed PTO didn't need to swap sprockets on the tiller to get the ratio right.
If your PTO doesn't have a built in over running clutch I would add one. If you bring the mower up to speed then step on the clutch and the tractor feels like it's getting pushed you don't have one. Mine was made by Speeco. It costs $60 and is an easy install.

 

[i7win7]

Couldn’t imagine what 1000 rpm implement that’s actually available you could run with a 13 PTO HP tractor but a generator setup does make sense.

Off topic but my B2650 has 2500 rpm for the belly mower. This pto is used when the front mount snowblower is added.

 

[NCL4701]

Off topic but my B2650 has 2500 rpm for the belly mower. This pto is used when the front mount snowblower is added.

The front PTOs and mid PTOs being high or model specific RPM make sense. Although my tractor had about 3x the HP of the OP’s it’s still a small tractor. My work tends to involve me in large ag equipment but only in the southeast US so there really are a lot of things common to other areas I’m just not familiar with. I routinely see the 21 spline 1000 rpm on large ag tractors and I always figured there had to be a reason for a 1000 rpm on smaller tractors because otherwise why would they go to the trouble to do it, but have never run across anyone that could explain what it was for.

One of my friends and I got to discussing it a couple weeks ago because he has a 30hp Canyon and I had taken my tractor and chipper over to his house to help with some storm cleanup. I think he was a little jealous of the grapple and third function on my Kubota but was surprised his has a 540/1000 PTO whereas mine is 540 only. We spent a little time trying to find ANYTHING he could get for his Canyon that required 1000 rpm that it has the HP to run and came up with nothing, at least nothing that’s available around here. It’s been one of those essentially useless pieces of knowledge that I’ve wondered about. Appreciate the knowledge.

 

[Russell King]

To the original poster, be very careful going forward and under the tree canopy for two reasons:
1) the tractor has enough power to just keep going and crush you drag you off if the limbs are low
2) if you have a roll over protection system (ROPS) a stout limb can catch the top of it and the tractor front will “pop a wheelie” and then crash back to the ground or worse the tractor could turn completely over.

If you do have the ROPS you should wear the seatbelt to be safe.

 

[terrib972]

To the original poster, be very careful going forward and under the tree canopy for two reasons:
1) the tractor has enough power to just keep going and crush you drag you off if the limbs are low
2) if you have a roll over protection system (ROPS) a stout limb can catch the top of it and the tractor front will “pop a wheelie” and then crash back to the ground or worse the tractor could turn completely over.

If you do have the ROPS you should wear the seatbelt to be safe.

Thank you for those tips. I have been considering getting a ROPS installed but haven't decided. My land is relatively flat and although I get nervous when there is uneven ground, I think it's mostly overreaction due to not really knowing the limits. I know my husband never worried about it but he had been driving tractors all his life. So I'm really cautious. I'm concerned it would cause me more issues with the trees. Won't be anything I do until next year when I get it serviced again so maybe I'll have a better feel for it then.

 

[random]

Just my opinion:
I'm a volunteer firefighter in a rural district. From what I saw in our Ag Rescue class: get a ROPS.