The MF example I am citing is a HST tractor, not a gear tractor. Power transfer from engine to PTO is not a "straight shot out" as you state. As you suggested in your earlier post, engine to PTO losses are significant in a HST tranny. I am not making up the loss data. It is FACT based on published data. Not my data. Not my gut feeling. Published data from the manufacturer I take to be factual. Nothing quizzical about FACTUAL data.
I was not disputing your quoted tractor loss, only calling attention to the need to take a harder look at the gear data because of the extreme difference between 14% tractor loss and the loss quoted for a gearset.
Please refer to my cited references. Reduction ratio is irrelevant to efficiency. Gearset efficiency is determined foremost on tooth interaction. Tooth interaction is based on tooth design. While all gear teeth make look similar, there is a large variation in design, efficiency and cost of manufacture. I'm speaking to differences in tooth design (profile) of straight cut gears. (Not between one gear types and another) Lubrication also is vital. Hardness is also important. If you refer to the references, the efficiency numbers assume gearset operating in a 90W gear oil bath.
I see nothing in Marks regarding relevance of ratio. Handbooks often cleave to average or accepted type of application and do not delve into special cases where the envelope is pushed a bit too far.
"Who would think of a 7 to 1 increase! ... and your expecting that efficiency? Sorry, forgot to tell ya...." Another thing unreported by the handbook is the actual way in which the test they get information from was conducted... Was it a dynamic test of the whole gear on gear
system or was it a static test measuring torque in / torque out x ratio, designed to measure only the loss inherent in the lubricated gearmesh. If dynamic, what bearings, what rpm? If done at high rpm, what are the particulars of the "oil bath"? In your zeal to contradict you are placing too much emphasis on information that is not complete.
Im hoping neither source actually said that ratio is not a factor unless they qualified the range in which it was not. Any handbook of mine that made such an unqualified statement would get a notation to alert the reader to investigate further.
Please understand, these references are not some theoretical calculation from some math professor. The references are engineering design handbooks.
Do you think the handbooks do the tests themselves? Gear on gear efficiency is very high for spur/ straight cut gears, and the math professor would show you why. It is the fact of very little sliding as the teeth mesh and "roll" thru the contact arc. Some sliding does occur however as a result of the distortions of loading. The math can factor these out and phase them back in easily on paper. Certain test design can do this in a system to quantize the losses of specific parts. We know nothing about the design of the test the data is quoted from.
This statement is irrelevant. The cited efficiencies are based on gearset in oil bath.
Again, is the gearset
running in an oilbath and
system input/output compared... or been run in an oilbath til in broke in and then measured statically. If its a dynamic test define the oilbath. How deep are the gears in the oil. What rpm? The statement about light oiling is appropriate in the dynamic situation.
On what basis do you conclude this heat results from a 1:6 speed increase and excess oil? On what basis have you quantified this heat dissipation? It would be interesting to see as we can then invalidate the accepted engineering design basis published in every mechanical design handbook I have ever encountered.
You have some objective basis for quantifying 10% vs 5%? Other that what it seems like to you?
Actually its closer to 7:1 when you think about it, [3600\540]. It seems you would ignore the fact that there is a point where "this is much hotter than that" becomes an objective determination. The reasons are things I know that contribute to the observed effect. Also, helical gears are used to ease the mechanical issues with the realitively tiny driven gear [which appears to be ground onto the end of the alternator shaft]. This geartype suffers greater losses than straight gears.
The facts remain. 13% loss to PTO on the Massey GC2400. 2% gearbox loss based on engineering design reference unless you can produce a reference to refute this.
Since it does not seem so I do not accept it as gospel. There are undoubtedly references that would deal with this more fully than a handbook. It would be good to be able to find a reference that discussed all the conditions of the real life power transfer in dynamic system application; ratio effects, motion effects, gear loss, bearing loss, viscous drag, windage, seal drag
, etc. You can be sure that 98% efficiencies are not found in dynamic systems that have not been subject to scrupulous optimization for the specific condition of use. 90-95% is prevalent.
larry
We love the house, and I like steam, but I know some wouldn't like this type of system.
