Gearbox Oil Additive

[yoshi]

Hi AllWaddles - the following table was the one I posted originally in regard to the varying types of oils that had been mentioned

[Brian]

Ah, huh, all starting to make sense now, the extra hp of the 2.5 is just too much for the gearbox so it looks like a new box which is probably a good thing in one way,I"m still perplexed as to why only 25 hourly oil changes, I"m really wondering why excellent quality oil cannot be good for at least 250 hours. ???

[yoshi]

Hi AllBrian - I think you already know the answer to the question, if we read between the lines it appears that the gearbox in question may not be really suitable to its current application given the HP that its being subjected to. The thing we have to keep in mind is that I am sure that Neil could design a box with all the bells and whistles that would do everything that we ask of it and probably more infact but the big thing comes down to cost. I dont know the cost of an Autoflight box but guess its probably $5000 or thereabouts, to some guys this is an affordable option and to others its not, now just imagine we have a box that anwers all our wants and needs for every application and you would probably be up for $10000 for that box. The main factors limiting the oil useful life in this box is the constant heat and the load that it is being exposed to, mineral oils do not like to be exposed to prolonged high temps, infact no oil does, as previously posted for every 10c increase in opearting temp, the useful life of the oil is halved or another way to put it is the rate of oxidation (degredation) doubles. Lets assume the following

[tonydenton]

just thinking about things, the photo you have posted of the output gear allan is an unusual design. i know we all want to save weight but to put holes in it like that, what it would save would be absolutely minimal really [and i personnally wouldn"t of,designed it like that.

[Brian]

I reckon a Autoflight was about $3,000 some time ago. A rotax C box was $1700 approx 2 years ago and I"m not sure what a Hirth box is worth.Interesting data you show there in regard to an increase in temps and casting my mind back a bit when I first got this current gyro, it had a Suby factory turbo ed/ EFI engine [1800 ]. I had Rosco put a engine oil temp gauge in it and that made very interesting reading. S&L at minimum revs, temps were in the green but as soon as you started to work the gyro, the temps soon got close too or into the red. No good for my line of work. Tim Mac installed an oil cooler and it was surprising to see that at first, there was not a lot of change to temps so we shifted the cooler around and on the 3 rd go, got it just right as you could really work the engine hard and the temps remained in the green. The oil changes during this time pretty much verified the gauge readings.When Tim Mac put the 2.2 in, we didnt worry about hooking up the temp gauge but I often wonder just how warm or hot the engine oil in a 2.2 actually is and if I was installing a new engine again, I would definitely have a oil temp gauge.Whats this got to do with gearboxes, well, lots of machinery gearboxes now run oil coolers, particularly on heavy stuff, so why not on a Autoflight gearbox, a bit of fiddling but I reckon it would pay for itself proper quick .. What does everyone think ??

[tonydenton]

i agree brian, allan isn"t chasing anything like you but the gearbox doesn"t know any difference.darren also commented that the gearbox COULD BE

[birdy]

Never run Moryes at more than 30%, in any application..

[tonydenton]

i really only ment the pro ma test to se if if actually reduced any heat even under the damaged gearbox situation. as i"ve said none are "spanner in a can".nothing like a new everything to fly with.

[Waddles]

Thanks again guys,Tony. I don"t know what type of gear is in the H6 box that Neil recommends. I"d imagine it"s from the same supplier as mine so would be similar. Don"t know. I"ll be using viton seals in the rebuild and i don"t have that haf of the bix here so can"t confirm if the sight glass is plastic or not.I hear what you say about foaming. Had a discussion with an operator who stressed that in his experience, too much oil will cause more foaming than a little less. 500mls brings the level up to the top of the sight gauge. 400 mls is about 1/2 way up it. Maybe the extra 100 mls is contributing to any foaming that might be. But, how does one check for foaming? There is no evidence of bubbles etc in the sight gauge at any time, whilst running or immediately after shutdown. Any suggestions would be appreciated. Oh. Any oil that ends up in the overflow reservoir is likewise free of air bubbles, so I"m wondering if foaming is really a problem here. I think from my poor memory, that Neil said to fill to 1/2 way up the sight gauge, but that was 8 years ago.Re excess heat and it"s possible source: This over heating manifested itself quickly. I hadn"t flown for about 2 months during my hols overseas. It was when I flew it again after that (December) that the temp increase became evident. Initially I blamed it on the ambient temperature and this seemed to be logical, especially when during a 1.5 hour flight at cruise, the temp would return to normal. For the 275 hours up til then, there was no abnormal temp indications regardless of the weather. For this reason, I"m inclined to think that heat from the engine is not the culprit. Is it possible that in December when I started flying again, it just happened that the bearing was starting to fail causing the increased temp?Raises another question. Had an oil cooler been fitted, would this have masked the overheating so much that the first sign of trouble, other than discoloured oil was a major failure of the bearing? Any thoughts?Darren. Pardon my ignorance, but from your viscosity table, which viscosity is the better? The high numbers or the low ones? I"m guessing higher is better at higher temps, but need to be educated please. Not exactly sure, but O think the H6 box runs around the $4500 mark, plus freight plus GST plus, plus. Were i building a new gyro, I"d probably go down that track. Preliminary estimates indicate about $200 in parts for the rebuild and that"s with name brand bearings. So, if this lasts say 200 hours before another rebuild, I prefer that as an option from a monetary point of view, but those 200 hours have to be trouble free. Am I a tight a*** or not?Hoping to get the old beasring off tomorrow and rebuilt by early next week. Bearings have to come from Melbourne. I"ll get them overnighted so shouldn"t be a major holdup.Thanks again.Waddles

[Russell]

Thanks again guys, Am I a tight a*** or not?Thanks again.WaddlesYea..........tight as a fishes *rse. ( probably still got your lunch money from school days.............that"d be 100 yrs ago too ) ;D ;D

[Russell]

Hi All
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[Brian]

Darren.............interesting info, but poor ol russey is struggling here........my reading here is...recommended service interval of1000hrs seems to be the best result ???. ( looking at your comparisons )Russ, the 1000 hours is at a temp of 70 C and I doubt that any gearbox is running that cool. You can see that a temp rise of just 10 C halves the hours , eg a gearbox running @ 110C needed a oil change @ 63 hours. How many ales you drank Russ

[danny]

I see the chart and note that none of the combinations temp/hours go anywhere near the 25 hrs oil change that I"m doing..just wondering how all of that matches with anything we are actually seeing

[Waddles]

Went to the hangar to check on the Castrol oil I was using. Seems like it was the wrong type. It"s the transaxle stuff that Darren mentions in #91. Should be the SynTRANS, not SynTRAX. Based on his viscosity figures, I wonder!! Hey Disco, what did Neil write on the scrap of paper that came with your box please?Dismantleing is progressing slowly. The tool for the retaining nut works well with the 1200mm extension bar welded to it. An adaptor needs to be made to use a porta-power to remove the gear on the output shaft which is keyed as well as tapered. May also need a tool to extract the output shaft bearing as there doesn"t appear to be much room to fit a conventional puller. Hoping to start reassembly by next Friday.Once all the tooling is made up, Rod will be prepared to do overhauls on demand if anyone needs it down the track. should be cheaper than shipping to NZ and back and probably a weekend turnaround. We"ll see.Waddles.

[Russell]

One thing for sure.........if rods doing the work, it"ll be done spot on.Now Waddly ol son.......i"ve got all this here oil in me shed......that syntax stuff you told me to use the other month......now you"re saying it"s the WRONG stuff......i"ll post it down to you, with me receipt attached.........just send me a cheque to cover ME LOSS......