Sherman/ pto HP

- the PTO load from the generator varies & is based on electrical demand. The HP rating on the generator is at full load. You can run a bigger generator that is rated for 40+ HP just fine on your TO30 if you want, but, if your electrical demand goes too high, it will create too much load on the generator/PTO, and your TO will bog down below 540 rpms, maybe even stall. - to get quality power without voltage fluctuations, you need a steady 540 RPMs on your PTO. Your governor needs to be finely tuned to maintain that speed as you vary electrical load, and your throttle can't drift up/down. I just don't trust my 1950 TO20 governor & throttle to provide the accuracy you will want to run your computer, big screen TV, and other delicate electronics on back-up power.
- To get 540 RPM's, your engine needs to run ~2/3 full speed. I don't know the gas usage per hour, but I know it is going to be higher on your TO, than an engine sized just for the job. You may have an advantage with your Sherman- being able to get 540 RPMs at a lower engine speed.

George

Geo.

1hp = 746 watts
good running TO30 ~30hp

30 X 746 = 22,380 watts

My 25k/45k single phase generator, under full load will make a 80 hp tractor snort! It all depends on what your connected load on the generator is.

The answer is no. I have a 53 TO30 with a sherman, "It is really nice to have". I have tested the PTO RPM's, mine makes about 520 RPM in low and about 970 RPM in high. Like some others have said, the more gears you have, the more loss you have, but it is a lot nicer to have the ability to use a gear to meet your demands. I'm also sure it will make right at 30 hp, even after 50 years of work! Good luck, Paul

Kirk..

It is a little more complex; the answer is not a simple �no�. You CAN use your Sherman to make more power at standard PTO speeds. As previously posted, it is true that the Sherman will always dissipate some power (into heat), but this loss is small (probably about 0.3 Hp), but what is much more important is that you have expanded the capabilities of your tractor so that it can produce significantly more power to the PTO at a standard PTO speed of 545 rpm (or even at the current spec of 1000 rpm).

Refer to a cut from a Sherman brochure as shown above. Outlined in black you can see that the standard PTO speed of 545 rpm is developed at about 1500 rpm engine speed without a reduction (straight through). For discussion sake, let�s assume that a TO-30 develops 30 Hp at the PTO at this point. You can also see that the same PTO speed (545) is generated by operating the Sherman in the low range (see the outline in red) and running the engine at 2270 rpm (see the footnote in the chart). BUT�. the power developed by the tractor is directly proportional to engine speed so the power now will be 2270/1500*30 = ~45 hp; approximately 50% increase in available power at the PTO. You will be working the engine faster then Harry intended, but well within its capabilities. Another interesting point is at 1750 rpm engine speed with the Sherman in the high range (the green box) the PTO speed is 951 rpm. By increasing the engine speed to about 1840 rpm, you will develop 1000 rpm at the PTO (the current modern standard) at a power of 1840/1500*30 = ~37 Hp. Again you will be working the engine slightly faster than Harry intended, and you will have to buy adapters to match splines, but you have a very versatile arrangement.

Jim

PS For all of the detail oriented, the following needs to be added: The above assumes that all of the engine and gear box losses are linear with speed. This is true for most of the losses, but volumetric efficiency, for example, is not quite linear, so developed power will likely be a little less than the examples. Furthermore, as noted in the chart footnote, the engine governor will have to be adjusted to make 2270 rpm. The question always arises, �Is it safe at 2270?� In my opinion, yes, but that is just my opinion. The Ferguson engine is not dynamically balanced (no counter weights on the crank) so there will be larger unbalanced forces but factory recommended operating conditions for this engine are very conservative relative to its capabilities. I don�t want to recommend that you operate there, only I will say that I do.

No auxilliary transmission will increase the delivered power.In fact it will reduce the delivered power due to its internal losses which you also allude to.

The standard factory tractor configuration can be run up to higher rpm and deliver whatever increase in power that is, with or without the auxilliary transmission.

I think what you are trying to say is that with an auxilliary transmission, you can apply more useful power to certain tasks, such as rototilling, where you can keep a high engine speed and a low ground speed. You can't do this with the standard factory transmissions because the gear ratios are to high.

So, in my opinion, the answer to the question is that you won't make more power but you'll be able to use the power over a wide range of ground speeds.

"Respectfully,the engine power is what the engine power is and it is a non linear function of rpm (beside ambient pressure and temperature) you allude to in your post. It might be quasi-linear within a narrow rpm range but without seeing the power curve, I can't say that 2270 rpm on a standard day is still in the quasi-linear range."

It isn't what it is, it is predictable and is science, engineering and math... nothing mysterious about it... I am going to suggest that maybe you haven't seen enough power/torque curves to make some simple worthwhile approximations/generalizations about low speed low compression industrial internal combustion engines... I have seen engine power and torque curves... hundreds of them.. and I'll post a typical one here tomorrow, and it is fairly linear over a broad mid to high range band...not over a narrow range. This is not a high tech engine...

Power is simply Torque times rotational speed (P=T*N) (with the proper units of course)and what I discussed in the previous post was a simple approximation of nominally constant torque over the speeds in question (1500 to 2270 rpm) which is a good approximation for this type of engine. Then power is very linear with RPM in this range

"No auxilliary transmission will increase the delivered power."

Read my post again... I clearly did not say that the transmission "increased the power" What I said was that by use of the step-down, the tractor engine is able to make and deliver more power at the standard 545 pto speed (because the engine is running faster...) than you can without it (at the lower rpm.).. The point is, he is running a generator (or it could be any another PTO implement) and it MUST run at 545 so you don't have a choice of engine speed, you must set your engine speed to deliver whatever it can at the 545 rpm pto speed

"In fact it will reduce the delivered power due to its internal losses which you also allude to. "

Of course it will reduce the DELIVERED POWER.. The first poster said that too... but the DELIVERED POWER WILL BE MORE... at 545 pto, 1500 rpm engine, DELIVERING 30 hp minus 0.3 = 29.7 whereas with the stepdown, running at 545 pto and engine speed 2270 DELIVERING 45 Hp minus 0.45 = 44.5... It has more losses but so what...

"The standard factory tractor configuration can be run up to higher rpm and deliver whatever increase in power that is, with or without the auxilliary transmission."

Absolutely... but the point is, to use it for a PTO implement the PTO MUST BE AT 545 RPM... YOu must be at 1500 engine rpm with the standard configuration..you cannot run it up to 2270 without some sort of inline transmission..

"I think what you are trying to say is that with an auxilliary transmission, you can apply more useful power to certain tasks, such as rototilling, where you can keep a high engine speed and a low ground speed. You can't do this with the standard factory transmissions because the gear ratios are to high."

Again don't put words in my mouth. I did not try to say anything of the sort... In fact I am not talking about any ground movement.. Put blocks under the wheels... I am talking about being hooked up to a generator, a silage blower, any fixed speed pto implement and sitting still..

"So, in my opinion, the answer to the question is that you won't make more power"

Wrong..you will definitely MAKE more power at 545 pto rpm with the Sherman allowing an engine speed of 2270 instead of 1500.. a lot more power.. about 50% more...

"but you'll be able to use the power over a wide range of ground speeds."

totally irrelevant, this tractor is stationary

JIm

I have seen plenty of Hp vs N curves and I've never seen one that's linear and that's a fact. As I write this, I'm looking at a power curve for a CR 5.5 6 cylinder truck engine with a 4-3/8" bore and a 5-3/4" stroke rated at 145 HP @2250 rpm and the data is in "Internal Combustion Engines" By Obert(page 45) BMEP, BSFC, Torque, and HP are presented as a f(N)on a big scale and there ain't a one of these curves that are linear in N.
There are a bunch of these curves in this reference and there ain't a one that is linear and I don't see how it can be linear given that the mechanical losses aren't linear and the pressure losses in the induction system aren't linear especially in the high power range. There are curves of friction power, indicated power, "air consumtion", etc and not a one is linear. And this book is a 1950 edition.

Be that as it may, I understand your point about being able to get more pto power than if you limit yourself to the standard pto system at 540 with the factory 2.777 gear reduction. If the herman allowed you to get a about 4.07 you could use the engine at 2200rpm. I doubt you could make 45 hp @ 2270 rpm since the book says that it gets 30.3 @ 2200rpm(at least I think it's 2200 rpm; that's how engines are usually rated.)

I missed the part about the guy running a generator so that's why I used the ground speed analogy. Same outcome however. The auxilliary tranny gets you the power at more useful groundspeed/pto speed, whatever.

I look foreword anxiously for your linear power curve. Hope it has the data points!

I think that the hang-up is you are making too much out of the constant torque approximation.. By definition, Power is P=T*N and it IS linearly proportional to rpm (N) if Torque is constant. I guess what you are implying is that my characterization of torque as constant is not a good approximation.. What I will show is that for a typical ic engine, this approximation is close enough for estimating the power on the up side of the power curve that I was talking about.. at least until the high speed losses take over at high rotational speeds and high air velocities (the ones that turn the curves over at the top, that I specifically said I was neglecting)

Anyway, I have too much apart (including the TO-30) to spend all my time today responding.. but I will in time..(and that is not to be interpreted as a change of position, constant torque over much of the engine range is not a bad approximation)

I do enjoy our discussions.. inspite of my hasty 2 AM defensive response.. Jim

No question that torque and Hp are related by a simple equation(P=C*T*N), Jim ,but torque is not constant with rpm. Its somewhat parabolic, especially on these older engines where induction losses are large. These losses are not negligable.( From Obert, a typical frictional horspower, combined mechanical and air pumping is ~43% of brake horsepower at max power rpm!) If you put a specially tuned big induction system on the engine,you will reduce dT/dN, the slope of the torque /rpm curve, relative to a factory manifold, but it will still have a negative slope.(torque increases, hits a peak, and then decreases with N.) For the Torque curve to be flat, the sum of the friction and induction loses have to be constant with speed.( Valve timing gets into this, too.)

The other issue is the HP rating of the engine. For PTO use, the tractor engine is continuously rated at around 60-70% of max power. That means you can run 24/7 at that rating and get the design life out of the engine.

Not so at Max power. Max power is peak power(in the absence of a mechanical limitation) and the power curve goes through a peak and the power will reduce with increased rpm. That's due to the negative steepening of the torque curve and the above equation. The 30.3 HP rating on the TO-30 is at 2200 rpm to my understanding as it is the maximum power rating. Increasing the rpm above that will not increase the horsepower without mechanically modifying the engine. This limitation occurs because the frictional & induction losses are highly nonlinear as you approach max power and you can choke the intake valves, or the carb throat, or a portion of the intake manifold, for the stock design. because (This is why the dragsters run with high lift/high duration cams, and big intakes, the largest valves they can get into the head and non restrictive exhausts.Power~airflow. And they still have non flat torque curves.

So if I'm correct in my assumption that 30.3 HP @ 2200 rpm is max power on the TO-30, overspeeding the engine will not increase the HP. In fact you will get no more or even less power.

Having said this, there are some engines that may be rated based on a mechanical limitation( material limitation, structural limit, etc) and these engines HP vs N curves, while not linear, still never show the peak power characteristic maxima. Obviously whoever designed the engine didn't do it right because it can't achieve the design max power. The other case is that the engine was derated for 24/7 operation at a lower then design max continuous rating to increase the life. I don't think we are talking about these engines, however.
Of course none of this has anything to do with the ability of the Sherman transmission to better match the the 545 rpm power to someones generator. My point is that I doubt that overspeeding the Z129 above max power rpm will provide significantly increased power.