What size bush hog for the 2320 guys ?

[Marveltone]

When I first mowed the right of way (with the 60" cutter and 16.5 PTO HP), most of the brush was as tall as the cowl (about 48", I'd guess) and some as tall as the ROPS. Slow going (which since I didn't know what was under the brush, slow going was the rule anyway...even if I had been running a bigger tractor), but the tractor/cutter did fine. There was an occasional bogging, but not too much of that. It actually surprised me how well it did.
BTW, Land Pride's recommendation for the cutter was 20 PTO HP, minimum. By Land Pride's requirements, that's 4 PTO HP per foot of width (for a standard duty cutter...I don't think Land Pride manufactures light duty equipment).

So, in answer to your question "Can you tackle 5 ft high grass or brush with 16 hp?", the answer is "I did" (others might not have done as well, or may do better).

As far as the HP calculation....PTO HP is measured (or calculated) at PTO speed. I'm not sure how you came up with 65-80% since that HP curve is quite dependent upon a number of variables (cam profile being a biggie).
That old 670 (tractor described in my posts) developed 19 gross engine HP, 16.5 at the PTO. That's about 87%. My 4400 develops 35 Engine HP, 30 PTO HP...that comes to about 86%. I'm rounding the percentages, of course.
I'm not even sure where you came up with "Applying the 5 Hp/ ft rule is based on the full power developed". Never read that that "rule" other then as a subjective comment or guideline on TBN.

Cool! I guess by that reckoning my 1510 is running about 89% gross engine HP (22) at the PTO (19.5). I've never thought of it that way before. I love high efficiency! :thumbsup:

Joe

 

[techwrtr2]

Without knowing what type of terrain the OP wants to cut, I'll offer what I did and why.

I have a 48" KK rotary. When I went to purchase my mower, I would never have considered a 60", not because it could be too much mower for my tractor but because it simply would not fit. I mow between tight rows of spruce trees which as they are growing, it's gradually getting to the point where my tractor isn't going to fit. That point would be reached much sooner if I had a 60" mower. I do a lot of mowing in tighter spaces, not just in the tree rows so again the 48" mower is the proper mower.

:2cents:

 

[Transit]

When I first mowed the right of way (with the 60" cutter and 16.5 PTO HP), most of the brush was as tall as the cowl (about 48", I'd guess) and some as tall as the ROPS. Slow going (which since I didn't know what was under the brush, slow going was the rule anyway...even if I had been running a bigger tractor), but the tractor/cutter did fine. There was an occasional bogging, but not too much of that. It actually surprised me how well it did.
BTW, Land Pride's recommendation for the cutter was 20 PTO HP, minimum. By Land Pride's requirements, that's 4 PTO HP per foot of width (for a standard duty cutter...I don't think Land Pride manufactures light duty equipment).

So, in answer to your question "Can you tackle 5 ft high grass or brush with 16 hp?", the answer is "I did" (others might not have done as well, or may do better).

As far as the HP calculation....PTO HP is measured (or calculated) at PTO speed. I'm not sure how you came up with 65-80% since that HP curve is quite dependent upon a number of variables (cam profile being a biggie).
That old 670 (tractor described in my posts) developed 19 gross engine HP, 16.5 at the PTO. That's about 87%. My 4400 develops 35 Engine HP, 30 PTO HP...that comes to about 86%. I'm rounding the percentages, of course.
I'm not even sure where you came up with "Applying the 5 Hp/ ft rule is based on the full power developed". Never read that that "rule" other then as a subjective comment or guideline on TBN.

As far as "Question; how much can a FEL lift if the lifting force is 3,500 lb at the end of the lift arm?"...can't help you there. My engineering books are at work and my math is too rusty any more.

65-80% is the expected range of Hp, 87% is not that far off. Ideally, it would be best to run at a little faster than the maximum engine torque, typically around 1,700 1,800 Rpm. The problem is that the PTO would be running slow, less than 540 Rpm unless the transmission has the correct ratio.
The only way for sure to know what the PTO Hp is with a dynameters test. My King Kutter has 1 to 3.72 gear ratio, other brands maybe more or less, this gives a tip speed about 14,700 FPM . There is also the ability of the injector/governor to keep the engine at the set speed. At a constant speed any variation in Hp is all due to Torque that the engine can develop up to the point that the engine bogs down. Some diesel engines are capable of developing
100+ % of their rated power and just because they can is no reason to; it is hard on all the engine components, bearings, shafts, rings, etc. and causes overheating too.

I would suspect higher Hp tractors running the same size rotary cutter at PTO speed are less susceptible to overheating complaints.
Simply put, match the load to the Hp.

 

[Pushing_Tin]

My first tractor was the 2320 with the 48" Frontier. Like some have said it all depends on what kind of grass your are cutting and how wet it is. For me there's no way I could have run a 60" cutter on my 2320, in fact it's one of the reason I moved to a 3320.

 

[RoyJackson]

The only way for sure to know what the PTO Hp is with a dynameters test.

That's true, but most most of us don't have a dyno in our garage. So, we have to go with the specs the manufacturer provides which is gross engine HP and PTO HP (and PTO HP requirements being the most common method of rating a driven implement).

 

[Rob-D]

PTO HP is rated at the engine rpms that produce 540 rpms at the shaft. Implements may not be using all the HP and like Transit says, we don't want them to. One of the nice things about diesels is their long torque curve, you can run most of them at 1600 rpms and the HP is there when it's called for.
As for efficiency measured at the wheels or PTO, several factors contribute to it, gear angles, number of gears, combustion chamber dynamics, etc. A PR is slightly more efficient than the Hydros for example.

Rob

 

[RoyJackson]

PTO HP is rated at the engine rpms that produce 540 rpms at the shaft.

Which brings up a question....why 540 RPMs? Did the tractor manufacturers set the RPM and the implement manufacturers follow? Or vice versa?

Sort of which came first...chicken or the egg?

 

[Marveltone]

Which brings up a question....why 540 RPMs? Did the tractor manufacturers set the RPM and the implement manufacturers follow? Or vice versa?

Sort of which came first...chicken or the egg?

I dunno. I have a cart, but no horse!

Joe

 

[Rob-D]

Which brings up a question....why 540 RPMs? Did the tractor manufacturers set the RPM and the implement manufacturers follow? Or vice versa?

Sort of which came first...chicken or the egg?

Good question Roy. I've always thought that PTO rpms is a carry over from when they were first produced. Perhaps the implements back then were set up for the best tractors at the time and that's how they arrived at 540.
If you look at the mid PTO on my late model Deere it's 2100 rpms but in a way I sort of wish it was also 540 so I could use rear mounted snow blowers on the front of my tractor.

Rob

 

[Transit]

Which brings up a question....why 540 RPMs? Did the tractor manufacturers set the RPM and the implement manufacturers follow? Or vice versa?

Sort of which came first...chicken or the egg?

This will answer Why 540 rpm.

Some tractors PTO come 540,720 and 1,000 rpm.

Agricultural engineering other topics - Proper PTO ang velocity (rpm)

Power take-off - Wikipedia, the free encyclopedia


BTW, first the egg.