Well I finally got time to work on the engine. Based on advice from the thread on the 14/1 crank gear (http://www.slowspeedengines.com/forum/showthread.php?t=739 (http://www.slowspeedengines.com/forum/showthread.php?t=739)) I prepared to take the crank gear out of the engine. However I soon realized that this is not necessary. After removing the idler gear and crank balance weights one can reach the back side of the roller bearing and tap it off the crank. Then the broken gear slides right off. I found no damage to the crank.
(http://i292.photobucket.com/albums/mm31/akghound/Picture686.jpg)
You can use the oiler tube as a tool rest
(http://i292.photobucket.com/albums/mm31/akghound/Picture689.jpg)
(http://i292.photobucket.com/albums/mm31/akghound/Picture668.jpg)
Broken gear
(http://i292.photobucket.com/albums/mm31/akghound/Picture670.jpg)
Bad Crank Gear AND Bad Idler Gear
This is getting worst rather then better
To install the new gear I plan on heating it in an oven, however I really don't know how hot to get it. I'm thinking around 400* (f). What do you guys think??
Also posted at http://www.slowspeedengines.com/forum/showthread.php?t=770 (http://www.slowspeedengines.com/forum/showthread.php?t=770)
Ken Gardner
Ken. I cannot go to that link you provided and the registration seems to be disabled!?!
What gives???
if i recall correctly there is no keyway and key to position the gear, so it must fit pretty darn tight
so i would expect 400 degree's is not quite hot enough
if memory serves me the gear on a new crank has a dark purple or almost black look to it, telling me
it was heated to ~650 degree's F
now here is the fun part, you must make absolutely sure the crank has no burrs or scars that will impede the
hot gear from sliding on fully. stone, file or sand down any such blemish very well, make sure there is nothing to
hold up the gear or get caught under it, otherwise it will go on part way and you will be forced to use the indian
golf club (sledge hammer) to fully seat it.
depending on the bore size it might sit onto a 100 watt light bulb in a lamp, just sit the gear down on the bulb
and let it heat up, check the color and when it goes from full blue to dark violet/purple it is about as hot as it needs to
be,
pick it up with welding gloves and slip it onto the crankshaft, being certain to position the teeth where they ought to be.
probably a good idea to have a section of pipe to use as a driver to finish the install should it cool and lock down before it seats fully
far better to finish driving it hot that wait till it cools and then have to beat the crap out of it to get it seated, and probably set it up
for a crack in the process.
if you find after heating the gear it still won't start on the crank, it may have to be even hotter, i don't know how tight a fit they make them.
bob g
Getting it on is easy....but getting it timed properly may be a stinker! Geno supplied us with this excellent representation of the proper timing of the crank gear on a 6/1.....I'm guessin it's the same for the twin.
(http://genedevera.com/temp/6-1-crank.jpg)
Its going to be darn near impossible to juggle a 600 degree gear, drive it onto the shaft before it cools---in EXACTLY the right orientation.
Your not gonna get a second chance on moving it around if it's wrong.
I'll bet the gear was heat treated, annealed, hence the color Mobile_Bob noted, then pressed on cold. Or driven on with a piece of pipe and what somebody here aptly called an Indian golf club. (sledge hammer)
Ron
This post puts my pic on the Microcogen.info server for future reference if my site goes down or something. That's a Dursley crank as well.
Thanks, Geno
Quote from: vdubnut62 on January 02, 2010, 01:24:58 AM
Your not gonna get a second chance on moving it around if it's wrong.
I'll bet the gear was heat treated, annealed, hence the color Mobile_Bob noted, then pressed on cold. Ron
I have to agree with Ron....I would get it in correct timing rotation and drive it on....
I would get it in correct timing rotation and drive it on
I would respectfully disagree. I would not just drive it on unless as a last resort.
I would have the crank in a freezer on super-freeze at near -40, if there was not a local supply of dry-ice (or even a dewer of liquid nitrogen), or stood outside if colder, the gear mounted securely in a large easily-located block and heated in an oven. Two reasons - firstly for easy location in the correct orientation and secondly as a large heat energy store so the gear will not cool quite so quickly.
Either way, I would not even attempt it with the crank in situ.
Regards, RAB
Quote from: oliver90owner on January 02, 2010, 11:29:11 AM
I would get it in correct timing rotation and drive it on
I would respectfully disagree. I would not just drive it on unless as a last resort.
I would have the crank in a freezer on super-freeze at near -40, if there was not a local supply of dry-ice (or even a dewer of liquid nitrogen), or stood outside if colder, the gear mounted securely in a large easily-located block and heated in an oven. Two reasons - firstly for easy location in the correct orientation and secondly as a large heat energy store so the gear will not cool quite so quickly.
Either way, I would not even attempt it with the crank in situ.
Regards, RAB
I would agree with RAB, that is how I do most of my press fit work.
I evidently gave the wrong impression, I was not advocating driving the gear on cold, that would be my last resort.
Placing the crank in the freezer and warming the gear seems to be the best option so far.
I would probably try my best to discover how the "Dursley Boys" did it since it does seem that their method worked very well.
That being said, I will still bet that the Indian OEM procedure was a large pipe and an even larger hammer at ambient temperature.;D
Ron
Attention Moderator: We need a smiley whaling away with a gigantic hammer!
oliver90owner, I am curious to know what kind of large block you mean? Something out of iron?
This sounds like an example of something I need to learn and file away for future reference, I hope I never get too old or stubborn to learn something new.
Thanks, Ron.
I'll bet the gear was heat treated, annealed, hence the color Mobile_Bob noted, then pressed on cold.
Ron,
I fail to understand how I could have got the wrong impression from your post!
Steel is cheap and available. Chocolate would not do!
I would probably resort to machining a relatively massive (wrt the gear) holder to do the job. Right size, good thermal contact with the gear and with the gear securely fixed in position to be assured of good angular alignment. So probably cut and bolted together. Do one, do a hundred, the tool for the job would be a one off, so relativley expensive. Probably never used again. But better than a hammer job. First I would be checking accurately, and I mean accurately, the dimensions of these interfefence-fit parts and, of course, referring to the linear coefficients of expansion for the materials to see what delta T would be required.
I presume they would be jig-fitted at manufacture, for alignment, however they may have been persuaded onto the shaft. Once jig is adjusted, it would be fixed and correct forever (hopefully). I would doubt they are hammered on, pressed maybe, but almost certainly with some differential temperature assistance.
Regards, RAB
Regards, RAB
Quote from: oliver90owner on January 02, 2010, 11:29:11 AM
I would get it in correct timing rotation and drive it on
I would respectfully disagree. I would not just drive it on unless as a last resort.
I bet $100.00 Dursely or the Indians didn't put the crank in a freezer and heat the gear......of course that is my opinion.....and either way will work but most important is the rotation......
heat and fit gears are very common in my industry, over the years many engine manufacture used the method
for various parts,
cummins heated cam gear and slipped them onto the end of the cams, and still do on most all of there engines
all sorts of heavy gear case gears are heated and slipped on as well.
the last thing you wanna do is press on a gear and have it gall up and provide a lump that will end in a cracked gear
i have heated an aweful lot of gears in the last 35 plus years and have them slip right into place, cool and lock
down tighter than the hubs of hell.
personally i would not recommend any other method, even though i am sure other methods might work some of the time
and by work i mean work for the life of the engine.
there is a reason the original gear broke, could be from earlier cam gear failures, or just as likely it was because the oem gear
was beaten into place by a gorilla in sandles with a sledge hammer.
beat on the crank and you may very well bend it? press it unsupported properly and you will likely bend the crank? any stress likely
will end up as a problem in the fillet area, and maybe it becomes a broken crank later?
we can look to the oem lister for how they did it, but
can we really?
we assume the fit spec's are the same? a big assumption
we assume the metallurgy is the same? another big assumption
take the new gear and see if you can "touch" it with a file, my bet is it isn't hard at all
if it is then you gotta be careful as to how much heat to put on it,
if it files easy then it is not harden at all, and can be heated to 600-650 degree's with no
detrimental effects
heat it, drop and turn to position,
work fast and work clean
put a soap stone witness mark where you want the valley of the gear teeth to land
and do the deed
bob g
One of these days maybe I'll learn to keep quiet around people that know more than I do! ;)
Ron
XYZER,
I bet $100.00 Dursely or the Indians didn't put the crank in a freezer and heat the gear
I would not expect, and cerainly didn't suggest, they did.
All the freezer does is give an extra near 600 delta T for no particular effort. Might be important if that gear is susceptible to heat treatment.
I might have taken you on with your bet if you had said 'or' instead of 'and'. I think you chose your words carefully. You are running against the tide here, so start paddling!! :)
Regards, RAB
The question.........
Quote from: akghound on December 30, 2009, 05:41:58 PM
Well I finally got time to work on the engine. Based on advice from the thread on the 14/1 crank gear I prepared to take the crank gear out of the engine. However I soon realized that this is not necessary. After removing the idler gear and crank balance weights one can reach the back side of the roller bearing and tap it off the crank. Then the broken gear slides right off. I found no damage to the crank.
To install the new gear I plan on heating it in an oven, however I really don't know how hot to get it. I'm thinking around 400* (f). What do you guys think??
Rab,
I have done my share heating and shrinking and am fully aware of the coefficient of expansion/contraction and how it relates to temperature. Reading the OP and his situation of a down motor off grid away from town and living in Montana some where with a
crank still in the engine and that was my answer and I am sticking to it regardless of your opinion of the tide and which direction you believe it is flowing.
Quote from: oliver90owner on January 03, 2010, 01:58:19 AM
XYZER,
I might have taken you on with your bet if you had said 'or' instead of 'and'. I think you chose your words carefully. You are running against the tide here, so start paddling!! :)
Regards, RAB
Me.....choose words......FUC$ NO!.....I told him how I would fix it in the situation it is in and why I believe it an acceptable method! If you all think it just easy to heat a gear and slide it nicely on down inside the crankcase over the crank and get it properly timed
FAST! well jump on the boat and ride that tide!.... I would clean up the surfaces and press it on like it has been done for years. Is it the perfect way?.....NO! Will it work in his situation?...YES! We maybe also need to mention some of the pitfalls of shrink fit.....like if it cools before you get it where you want it....that will piss you off!.....Then what?
Dave
If the engine in question is in Montana, it's in a freezer already! It's 11 degrees here, and I'm in Tennessee.
In weather like this, a Bic lighter would provide enough heat to the gear. Almost. ;D
By the way just what is a "Delta T"? I missed that day at Percussion U.
Ron
somewhere in the discussion i lost track of the OP wanting to reinstall this gear with the crank in the engine,
no way i would even think to attempt this feat myself, the crank would have to come out so that i could get it
standing vertically, and perhaps most importantly, so i could closely inspect for burrs and other high spots that
would cause grief getting it back on.
sure couldn't hurt to chill the crank, and having an extra set of hand with a length of angle iron to index the drop
would be handy as well.
probably ought to mic the crank od and the gear id to see just how tight this fit really is?
don't know whether or not i would bet on precision from the indians, and precision in this area is the difference
between a heat and shrink, and how hot you will need to go?
bob g
Quote from: vdubnut62 on January 03, 2010, 03:10:41 PM
If the engine in question is in Montana, it's in a freezer already! It's 11 degrees here, and I'm in Tennessee.
In weather like this, a Bic lighter would provide enough heat to the gear. Almost. ;D
By the way just what is a "Delta T"? I missed that day at Percussion U.
Ron
Engineering jargon, it means the difference (delta) of temperature between two places, i.e. the gear and the crank.
Daryl
Xyzer,
Please read the thread. In my response (8th post on the thread?) I wrote, quote "Either way, I would not even attempt it with the crank in situ." Anyone attempting a repair like this in situ - well, I say best of luck and get on with it. You really need to keep up with the ball game and stop taking things completely out of the context of the posts.
Read my post again, carefully. You chose your words carefully (or maybe by luck, I dunno), but you said heating and freezing. If you had said, as I posted, heating or freezing, I could have won the bet but as you had said and you made it a no win odds, there was no point in betting.
If I were a manufacturer using a shrink-fit method, I would choose either heating or cooling, not both together. Certainly not 80 years ago. So your bet would be a no-brainer.
I often ask students for the probability of getting a head or tail when tossing a fair coin. You might be surprised how many get the answer wrong and say 'evens', 'half', or '50%'! They just a) don't listen to the question or b) don't understand why their response is wrong.
RAB
The correct answer is 'certain, 'one' or '100%', btw.
I call edge.
Supposing I was freezing my ass off offgrid this is how I would handle it. Mark new gear clearly with an index mark. Same for the crank. Scribe a line down the crank to line up the gear. Prepare a mild steel pipe driver of appropriate size. 1, 2, 4 and 8 pound hammers handy. Heavy brass punches at the ready for emergency adjustments to gear rotation. Polish crank with emery. Dry crank journal surfaces to reduce heat transfer. Heat up gear in oven to 450 f set up a brick in the shop with a rested tiger torch or hotplate to keep it real hot till you are ready to install it. Use leather welding gloves. Line it up and smack it home like a wheel bearing.
If you are a couple degrees out she will still run fine at reduced output and you can fix it in the summer.
Tim
Quote from: TimSR2 on January 06, 2010, 09:42:53 PM
Supposing I was freezing my ass off offgrid this is how I would handle it. Mark new gear clearly with an index mark. Same for the crank. Scribe a line down the crank to line up the gear. Prepare a mild steel pipe driver of appropriate size. 1, 2, 4 and 8 pound hammers handy. Heavy brass punches at the ready for emergency adjustments to gear rotation. Polish crank with emery. Dry crank journal surfaces to reduce heat transfer. Heat up gear in oven to 450 f set up a brick in the shop with a rested tiger torch or hotplate to keep it real hot till you are ready to install it. Use leather welding gloves. Line it up and smack it home like a wheel bearing.
If you are a couple degrees out she will still run fine at reduced output and you can fix it in the summer.
Tim
That is just what I did .... well almost.
I heated the gear in the cookstove oven to 500*(f) in a cast iron pot.
(http://i292.photobucket.com/albums/mm31/akghound/Picture699.jpg)
Then I took it out to the generator shed and drove it on with a post driver.
(http://i292.photobucket.com/albums/mm31/akghound/Picture717.jpg)
Pretty simple.
When I put the bearing back on I adjusted it so there is zero (Tight) end play on the crank. Keep in mine that I used the old bearings. I did however replace the rod bearings.
Ken Gardner
Congrats! is she running?
Zero end play seems a bit tight... I'd want .010 in. or so
Tim
Oh never mind. I just looked at your pics again. I see you have TRB's instead of plain shells.
I know, I know, the Indians smack everything together with a big hammer.
But did you know that they knew 70 years ago, and more, that you do not strike taper roller bearings with a steel hammer? Little wonder they fail early.
For instance, my Wisconsin VE4 service manual (1940s?) warns of the consequences of doing that with a TRB crank.
RAB
interestingly the japanese have a different attitude about how to install brgs
they ascribe to the use of a hammer and hardened punch!
their reasoning is chips generally fly out!
lmao, this is true, i got this from nissan back in the late 80's
perhaps they too have changed their attitude on this topic
of course they didn't have anything to say about the use of a sledge hammer :)
nevertheless, i still use a brass drift for the most part, a soft steel drift and sometimes a
standard punch if the brg surface is large enough. they are very easily chipped with an errant blow.
bob g
Quote from: mobile_bob on February 02, 2010, 02:40:22 PM
of course they didn't have anything to say about the use of a sledge hammer :)
bob g
What do they say about using a post pounder? ::)
Actually I set the bearing with a brass punch and a few taps from a light weight hammer.
Ken Gardner
If it was costing $20 a day, I'd beat the SOB on there with a damn rock if I had to!
Ron
Quote from: oliver90owner on January 04, 2010, 04:49:53 AM
I often ask students for the probability of getting a head or tail when tossing a fair coin. You might be surprised how many get the answer wrong and say 'evens', 'half', or '50%'! They just a) don't listen to the question or b) don't understand why their response is wrong.
1) What is the probability of getting a head or a tail when tossing a fair coin?
Answer: 1
2) What is the probability of getting a head and a tail when tossing a fair coin?
Answer: 0
3) What is probability of getting a head when tossing a fair coin?
Answer: 1/2
it all depends if there is a dab of clear silicone on that fair coin!
:)
what are the odds its neither?
bob g
Newbie here to Listeroids. But I know what my experience is with 8-10 other diesel engine manufactures is. Going to try not to sound like a jerk bringing this long dead, thread back from the dead.
Basically skimmed thru the thread after a page and a half, and by all means beat me with a broken listeroid connecting rod if I missed it.
Not anywhere did I read that anybody has basic machining tools, they may have them just did not use them in this case? Hard to know. The fit between that crank gear and the shaft is a interference fit, correct? If it is what were the measurements of the gear at room temp and the shaft at room temp? Gonna guess the crank gear is .004-.005 smaller than the shaft it fit's onto. If this is true then the best way for a guy working in his home shop is simply heat the gear and press it on. But, Better have a way of fixturing either the gear or crank so it slides on in correct location.
Not going to get involved in how to go about beating it on with a hammer or using a fixture in a press, you have to figure that out. My guess is that gear is never supposed to come off after installed from the factory. Which is probably why you cannot find out how the "boys in dursley" did it in any factory manual. If dursley did it wrong it was fixed by factory,dealer, etc. Warrantied?
Guaranteed the indians heated the gear up and hammered it on the shaft.And hoped to get it close. Maybe they did have a fixture but it may have been worn out after 250 engines etc.Just like the rest of their tooling.
I find it strange that I did not read about a micrometer and a dial bore gauge (or even a set of cheap snap gauges) to measure the actual clearance of the two parts to come up with a reasonable way to assemble them. If the part does not have a taper or keyway, how else is it to be put together?
Anyway like I said sorry for bringing up the dead,and am not trying to be a know it all because I am certainly not. But the 2 pages of bickering on the gear fitting subject puzzled me. Again sorry for the long rant as well.