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HB212 Working RPM


Steve72

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I had this in another post that was losing steam so wanted to put it here to get opinions of other 12hp Briggs owners. I checked the RPM of my HB212 when cranked up to what has always felt and sounded like a good working speed to me. With the throttle almost all the way---but still had a little--my RPM was 2,800. Much below the 3,600 that a couple have said you like to run. I couldn't get a reading on the snow blower auger as the shaft was not center drilled. Regardless, I am either babying my Briggs or your tractors are newer and built to run faster? Also---I removed the snowblower after about 15 min of using it and went back to my blade. Faster, cleaner, no constant white-out and just more fun rolling that snow over!
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I have never clocked mine to study actual rpm's; but like you, I run mine where it feels good and sounds good. Factory/dealers etc all tend to recommend full throttle operation. I run between 1/2 and 3/4 throttle, and it seems adequate. My tractor is old and I do tend to baby it somewhat; but it's really more about what feels like good smooth operation. Only time I crank it full blast is after the work is done and I am on my way back to the garage - I figure that's adequate to keep it honest, and perhaps blow out anything resembling carbon deposits. It's also fun to make a ton of noise just before shutdown. For me, full throttle is available if I really need or want it - but as a full time thing, uhhhh no thanks. For just "puttzing" around the yard or riding my little forest trails, I use approx 1/3 throttle. The hydro trans is in play with rpm's also; but all it needs is some basic rpm's to maintain standard pump pressure, and I think after a certain engine speed it's pretty much all the same, the pump looks after itself. Running a hydro too slow, as in real slow, will kill it. That's my approach, it's what I do, and afaik it's ok - I am very willing to be corrected esp. if any of my doings are damaging - but I doubt that. About the hydro pressure/rpm, I did not know that in my early days here, and was glad to receive info I knew nothing about. (Note the use of the word "pressure" might be "technically" incorrect - hydro-tek is a whole other world). my 2 cents.
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I agree my mowing on regular lawn is between one half and three fourths---full out just is too much and back to the barn at close to wide out would make that coffee can muffler sing. Just doesn't seem right on the old beast to go full out like the newer ones that to me are more designed for that---both power curve and emissions wise--one of the things I like about these oldies are that you just don't set the throttle and go----there's still some driving to them----when you get the same results at one-half and the engine isn't struggling -if it feels good- go with it.
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I have 3212H for my for snowblower project and in 2010 I used it to blow snow at 1/2 to 3/4 throttle. I have had and used these old tractor for 40 plus years and you dont have to run them full throttle to get the job done.At these throttle settings the hydro does fine . I keep the ground speed at what I feel is easy on the tractor and I can tell by the sound of the engine if it pulling to hard.This winter the tractor is in the shop in the process of a custom cab build Steve I will try to get some more pictures to you. I have tryed to post some to this site and I just gave up .Too much trouble to get to work. Maybe later.
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Ok--thanks guys. Just wanted to make sure my sense of what "feels right" wasn't diminishing with age and that I should be running it over 3k or so when working it.
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About hydros - running on idle speed is death. Anything better than 1/4 throttle will allow a hydro to build adequate simple operating "pressure". For hard pulling, works, etc - give it more like at least half throttle. I said "pressure" may be tek-incorrect because the hydro bypasses, check valves, etc. any notion of excess pressure. So there is no pressure if it's not doing anything - it's more about controlled and channeled fluid flow. This is some kinda rocket science, and requires extensive study to even speak about it. Just make sure, in use, that you give it a chance to do it's job, by utilizing reasonable minimum rpm's on the engine - beyond that, the Sundstrand people already engineered everything for you, and it works. Horsepower required to run a hydro is low - like maybe 5-7 hp. This is interesting because a 10hp tractor can do a lot of the same work that a higher hp tractor can do - translation - you just need enough hp to spin the hydro pump - the rest gets into a discussion on the bogus horsepower wars - see Crapsman, etc - it's a waste of gasoline. And this is what makes these olde iron tractors so amazing - they have a real transmission. I might be saying it all wrong; but I know the idea is correct. And these tractors have lots of hp in reserve to "spin" other things like mower decks and snowblowers. If you have adequate "reserve hp" then you can do anything. And so the real world difference between say an AC712H and an AC716H is not much. But it's all different with geared trannys, where it's actual hp doing the work. want rocket science? - fill your boots, you can start here - caution this link may be mind-boggling. 8) No, I don't fully understand it. but if you really want to know: http://www.edgeroamer.com/sweethaven/mechanics/hydraulics01/default.asp?iNum=0308
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The older tractors with the splash oiling can be run at whatever speed feels correct. At any speed above about 1/4 throttle they are getting plenty of oil. It has always been my opinion that running these old engines at WOT all the time will dramatically shorten their lives. I only run my older engines fast enough that the engine is not laboring and is running nice and easy. Heavy loads will always require WOT on any engine. The newer engines with the pressurized oiling systems and the oil pump should always be run at 3600 rpm when under a load. This assures adequate oil to the critical parts and also adequate cooling, since the oil removes a significant amount of heat from the internal rotating parts. This is my opinion, others may see it differently, so use accordingly.
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During mowing season I view throttle like a large jet. You have "takeoff or emergency" power but don't dwell on it unless you need it. Fuel consumption would be the main reason behind it, but other items like connecting rod stress or valvetrain wear can be inferred along with it. The manual from the factory however rates these engines as being "fit for constant load and constant rpm" up to 3600-3800(in some cases). I usually end up using 70-80 percent as the cruise setting, which saves significantly over 100 percent open with most of the available ground speed. My take on "babying" is a bit different from most. If the engine is rebuilt with a new rod, rings,piston I will treat it as it came from the showroom. If it hasn't been rebuilt, a little more conservative but I have seen a lot of coke buildup from being too cautious. It is healthy to get the cylinder head up to pressure and temp most of the time to put it how it needs to be.
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Josh it does make sense to me to blow out the cobwebs occasionally and I think I'll open her up (+3k) from time to time to do just that. Blaze I await your new cab posts and was showing my wife/kids what you have done so far--real nice. Mystik--you are a wise man...and can read between the lines. Ray is a walking tractor factor and we are gratefull to have him as Pres.. Lots of knowledge on this site---inspiring!!
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I am delighted to be elevated through inclusion on any list of the stars on this site; however, I can only give back what has been given me. My expertise is largely way off the beaten path; and much is afforded me in that place also; my handle here is an announcement of that. As for "between the lines", I humbly agree; but I often identify with other things and miss the main point. sm01 I would like to see your post count multiplied by at least 10, for starters. Peace. And, as to RayS, he constantly amazes me also. Inspiring, expiring; the normal ebb and flow; like breathing a breath of fresh air, and breathing out the old. That spirit doesn't often show on other sites; and this site has a strong spiritual foundation - hence, it's power, and our unity. There is no lack. Breathe in that spirit, and release, that more may come. And it will, as it is our will. One of the joys of "seat time" is listening to the music in the supposed 'noise'. Always wear 'ear protection'. :D
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For plowing, with my large frame tractor: 10hp Briggs, gear trans, 2nd gear, tire chains, no wheel weights, (big fat guy on the back, though); air, not fluid, in the tires, slightly underinflated, 36in plow, on mostly level terrain: one-third throttle. Results in easy shifting, a decent speed, and almost no wheel spinning. Tractor will do that all day. I would improve with a 42 plow. It would be wider than the tractor track when angled. They are built to work, and I am always impressed with that. I know my 2003 17hp Deere wouldn't do any of that.
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