PTO Q

[repete]

Does anyone know which kubota's in the 30hp range have two speed PTO's? The reason I am wanting the two speed is I use a bushhog 6' mower to do about 30 acres in five acre portions and it is usually light grass. Running the PTO in the 1000 RPM range means my tractor engine runs considerable slower to obtain the PTO speed.

I have enjoyed my L2550DT tractor as it has the two speed PTO and the subframe backhoe but with about 6400 hours +-I think it is time to retire it to second line duty.

 

[ptsg]

I don't think Kubota offers 540E in the US market in that HP range, but could be wrong. I know some of other manufacturers do. It's a great feature to have.

 

[JWR]

Does anyone know which kubota's in the 30hp range have two speed PTO's? The reason I am wanting the two speed is I use a bushhog 6' mower to do about 30 acres in five acre portions and it is usually light grass. Running the PTO in the 1000 RPM range means my tractor engine runs considerable slower to obtain the PTO speed.

I have enjoyed my L2550DT tractor as it has the two speed PTO and the subframe backhoe but with about 6400 hours +-I think it is time to retire it to second line duty.

There are some "yes, but wait a minute" aspects to your post. That bush hog is intended to run at 540rpm, a hair over half the 1000 rpm setting you are thinking about. You were obviously thinking about running your tractor engine at lower rpm while using the 1000 rpm PTO speed setting but that would mean running the tractor at roughly 50% of the routine normal operating engine rpm to get the PTO down to 540 ballpark. "That ain't gonna work right." Light grass or not, you are better off running the std 540 rpm PTO and std rated engine rpm. If you have light grass to cut that just means you can run a higher gear and do it faster. I do not know whether newer Kubotas offer a single PTO shaft running at 540 or 1000 rpm (?) My impression of the market is that 1000 rpm PTOs use an 11 spline rather than 6 spline shaft... a lot of unanswered questions which I realize was the heart of your original inquiry.

 

[Eagle1]

Mowing faster is not always an option due to terrain, but moving slower and having the mower at rated speed is not a bad option to have.

What is economy PTO?
Economy PTO is a feature that allows the operator to run the PTO at 540 rpm, but at a lower engine rpm than the standard PTO rated speed. Depending on the transmission, the 540 economy PTO setting could be as low as 1600 rpm. Economy PTO allows the tractor to operate at the required 540 rpm at the PTO but with lower engine rpm, which saves fuel, reduces vibration, and reduces noise.

Some manufacturers have advertised economy PTO settings that simply reduce the engine rpm only and do not actually change the speed of the PTO shaft. This not only reduces the engine rpm but also reduces the PTO rpm, causing implements to run at slower speeds. Operating a 540 implement at lower than 540 rpm at the PTO reduces its effectiveness.

How does it work?
On John Deere Tractors, the shiftable 540/540E mode operates somewhat like shifting gears on the transmission. By engaging 540E mode, the operator changes the gear reduction ratio keeping the PTO spinning at 540 rpm but lessening the engine rpm. When the operator shifts the PTO into the standard 540 mode, a different gear reduction ratio is used to operate the PTO at 540 rpm at the standard PTO rated speed of the engine.

To operate in economy mode, the shiftable 540/540E must be in 540E mode. Then the throttle can be increased to the appropriate rpm. When in 540E, the tractor has a throttle limiter that keeps the operator from increasing engine rpm over the 540E setting. The limiter is used to prevent accidental over-speeding of PTO implements and protection against binding the PTO shaft.

When to use 540 economy mode?
540 economy is ideal for many applications including mowing, baling, or tilling. The 540 economy setting cannot be used with full advertised PTO horsepower (hp). If full PTO hp is required, the tractor should be run in standard 540 mode.

 

[JWR]

"And furthermore..." adding to Post #3 above, I have some B2150 older Kubotas that have a 2 speed PTO. Those have 700 and some rpm (704? 740?) and 540 rpm choices. Those choices apply to both the belly PTO and the rear PTO. In the same kind of mode you were wanting to run -- using the 700 rpm PTO setting I can run engine rpm about 30% less than full, run in 2nd gear instead of low and mow most places very well with the std 540 rpm bush hog. In effect that gives me an "in between" over the ground speed option while keeping the PTO rpm still around the std 540 while running the engine 30% slower than rated. Works fine but that is with a roughly 30% factor. Your plan at roughly a 50% factor is just too far off in my opinion.

 

[5030]

I don't think Kubota offers 540E in the US market in that HP range, but could be wrong. I know some of other manufacturers do. It's a great feature to have.

That is correct but, Kubota offers a 2 speed flip shaft PTO. I have them on both my M series. 540 6 spline and 1000 21 spline.

Having said that I do believe Kubota offers an 'E' variant on the newest large frame units.

 

[ruffdog]

Just because the OP is running the engine at half rpm using the 1000 rpm pto, it doesn't mean he will burn less fuel or cause less wear. At that lower rpm, the tractor has much less HP to achieve the work (look at the power curve chart). Also, to maintain that low rpm, the governor is having the injector pump dump fuel at a higher rate than if you just ran at 540 pto rpm. All the while the engine is at a low rpm, the fan and coolant pump is not running at the designed speed so it has a increased chance of overheating. No, I would NOT do what the OP wants.

 

[JWR]

I agree with ruffdog when the lower engine rpm indicated by the plan is down by 50%. Some mfrs (apparently Deere being one) offer 2 speed PTOs that allow you to drop engine rpm some much smaller % like 20 or 30% which I'd support but not 50%. The "flip shaft PTO" Kubota models that 5030 mentions seems worth looking into.

 

[ruffdog]

Now if you were running a 5 foot cutter behind a 70 hp tractor....by all means run the faster pto because you have plenty excess power. A 6 foot cutter on a 30 hp machine should stay at 540 pto speed.

 

[ptsg]

I don't understand why such a big deal on using 540E or even 1000 RPM at less engine speed. For the OP to be running a 6 ft cutter behind a 25 HP tractor, clearly he is not mowing anything thicker or dense at all. If it was putting any sort of the load in the engine, pretty sure the OP would notice it as the engine would bog down quite hard.

I do so much work with 540E, even loading it down really good and had absolutely 0 issues. At 6400 hours, I don't think the OP had any issues either.