Gear 6589 interspersing ability

[Grosse Kind]

Good morning. Wondering on the 12 tooth bevel gears adaptability for purpose please. Have learned that they superceded the 14 teeth variety yesterday and looking in LDD (nifty little creature that one. Bit finnicky in places but enjoyable) its not a specifiable part unless i'm not looking jn the right spot. Will a 14 and a 12 mesh at all and if so safely? I've not shattered any 14's thus far but, pardon the pun, those i have are getting long in the tooth (between 20-35 years old. I recently had an 8 shatter and the guts blow out of a 3 axle position 24 but at least i have an adequate abundance of these) and when one too many do eventually go bump in the night for my spares reserves, i'm screwed.

Will a 12 take adequate drive if at all from the old style crownwheel and pinion type 28 tooth differential? Although described as more robust than the 14, it has the unfortunate effect if the two will run together of upping the overdrive of wheel to transmission on my baby which already has a pretty low overall ratio from crank through drive axles and the massive inertia of the rotating assembly already loads up the 14 that had previously caused it to skip under high load. Thereby, the universal joints are going to cop an ever greater pounding than they were exposed to. Theres not a whole lot of room in the chassis to throw a further compensatory reduction setup into play to make life easier on the pinion or trans without a lot of redesigning that i'm hesitant to broach.

Thank you for your time and hope i've posted this in the correct section.

[Zerobricks]

12 and 14 tooth gears dont really mesh well, did you try it with real bricks?

[Blakbird]

The old 14 tooth bevel gears really only mesh with themselves or with the old differential.

[Splat]

I needed to get a gear ratio of 7:10 for a MOC that I was making. I used two 14 tooth gears mated with a 20 tooth gear (see images below). This worked perfectly fine for me, however I didn't have much torque going through this gear train so I'm not sure how strong it would be - I was just synchronizing the rotation of a turntable (56:8 = 7:1).

The same can be done with a 12 tooth bevel gear, however you need to introduce a half stud offset between the 14 tooth gears and the 12 tooth gears. You also have to be careful with the orientation of the 14 tooth gears so that they line up properly.

As shown in the pics below, the 14 tooth gears aren't half a stud thick - they are closer to a third of a stud. If you push the 14 tooth gears together so that there is no gap between them, then they don't mate with the 20 tooth or 12 tooth gears very well. Under high torque this 'might' be a problem as the gears 'may' slide along the axle a little bit (maybe?).

I haven't tried to get the 14 tooth gears to mate at a right angle at all, nor have I tried to mate the single (half stud thick) 12 tooth gear with a single 14 tooth gear, so I'm not sure how that would work out. I suspect that the gears would skip though.

If you are breaking gears with your drive train, I would look at ways to redesign it rather than looking for stronger alternatives.

Edited February 7, 2015 by Splat

[Milan]

I can confirm what Splat says. I used 14 teeth gear in a similar setup for low torque applications and they work very smooth.

[Grosse Kind]

Thankyou for the replies.

Zbij: have not heard of realbricks as yet. I take it the full compendium of gears/parts both new and old (discontinued) is made available in it? Thanks for the suggestion.

Blakbird: i think that your answer covers the basics quite nicely. Would it be fair to say that a 12 will take the place of a 14 if all 12 or all 14's are kept exclusively like to like parts? My main concern (hope) is that if a 12 can be used as drive from (as opposed to just in and providing the action of) the 28 tooth old differential, then one or more may be worth procuring as a safeguard to stressing out the 14's i'm currently reliant upon that have already demonstrated a propensity to skip and may eventually through age and brittle tendencies, someday stop skipping and simply crack.

Will a 12 and the old differential mesh happily and with durability together?

Splat and Milan: ta muchly for the tech imparting, i'll catalogue that for later use once i get into studless and its myriad intricacies.

So far i've no dealings with any of the newer gears from the interim of my hibernation in the 90's. Sad as it sounds, my introduction to the novelties of 6539's, 6542's, 6573's, and the grooviness of (8 of the suckers per in fact) 2907 and what it and 2999 have made a possibility though now 21 years old, hit me as as big a revelation to others when they were new, only 3 months ago.

I've a degree of catching up to do that made the term "dark ages" i've noticed reading other expats posts rather apt. Not sure how i'll go with it all as with the exception of the old and new differential casings on size and structural grounds, what i've always loved with lego was the possibilities afforded by the restrictive parameters of its design. Knowing what would or wouldn't work by the constraints of what was out there to build with and all assemblies being a complex unification of singular components was what drew me to Lego and particularly technic of old.

The newer sets seem to leave some of that out insofar as being more aesthetic and to make a panel for example thats now a single piece of thin sculpted plastic with compound curves once was a longwinded or non event involving tens to hundreds of bricks.

The reduction dropbox hubs on the unimog i'm considering as my intro to the new are another example of the one part replacing a multitude of complex assembling of sole components to make, and would end up grossly out of proportion to the whole. I guess i'll just suck it up and dip my toes and see if the new style appeals to me.

Edited February 7, 2015 by Grosse Kind

[DrJB]

never mind.

Edit: I wrote question then deleted as I thought it was way out of contest and possibly not 'appropriate'. OP replied too quickly , with very kind words.

Edited February 7, 2015 by DrJB

[Grosse Kind]

"forgive my curiosity but, what is you native language? your sentences are very long and some of them seem as if translated from non-english. Again, i'm just curious. the reason I am asking is, i have met people from different parts of the globe, and often just based on how they construct their sentences, you can almost guess where they're from. I hope my inquiry is ok, otherwise please ignore."

Hi DrJB. Australian english. Inquiry is more than ok.

Also, now intrigued! Were you to have hazarded a guess, where did i sound like i originated please?

[Josephiah]

The old 14 tooth bevel gears really only mesh with themselves or with the old differential.

The old 8856 rescue heli has them meshing with a 24 tooth crown gear - a construction I've always found odd and out-of-character for TLG!

[Erik Leppen]

It can work. But it's not "in system".

I have used it in this case to create a driven steered axle without universal joints:

(Again, it needs a 0.1 stud offset, hence the yellow plates)

What's also interesting is that two 14t gears placed with the flat sides towards eachother, can work as a sprocket for a chain. As the 8t and 12t don't work as chain sprockets, double 14t is the smallest chain sprocket.

[DrJB]

"forgive my curiosity but, what is you native language? your sentences are very long and some of them seem as if translated from non-english. Again, i'm just curious. the reason I am asking is, i have met people from different parts of the globe, and often just based on how they construct their sentences, you can almost guess where they're from. I hope my inquiry is ok, otherwise please ignore."

Hi DrJB. Australian english. Inquiry is more than ok.

Also, now intrigued! Were you to have hazarded a guess, where did i sound like i originated please?

Thank you, and very 'pleased' to meet you. At first I guessed German or something with the same roots I worked for a German company in the US, and some of the colleagues would, I felt/thought, make sentences and compounded words that led to long expressions. I was wrong of course. In school I've met people from many countries and after a while I could pick up where they were from from just reading what they wrote. It did not work all the time, but it was a fun exercise to 'guess'.

[allanp]

In the past I have used 2 12 tooths and a 14 tooth in a differential to create a limited slip diff.

[Grosse Kind]

Will a 73071 accept drive at 90 degree to the outer 28 teeth from an 12 tooth 6589 as per the drawing herein if the YELLOW brick was removed and the entire RED assembly was moved one stud closer to the BLACK brick taking the YELLOWs place?

I know the differential i've used in the picture is not the same as a 73071 as per my technic model 8850 but i'm not having much luck explaining the question otherwise.

If i had access to a 12 tooth i could test all this myself but i've never even seen one.

Thankyou in hope in advance, glen.

[allanp]

Should work. That diff has 28 teeth just like the old bevel driven diff.

[Grosse Kind]

Thankyou kindly allan. I'll look at purchasing some of them or a set that contains them now.

As a last ditch verification, is it possible for someone posessing the two aforementioned part numbers out there to physically test if they will work as explained in my last post please?

Edited February 7, 2015 by Grosse Kind

[Captainowie]

I've just thrown something together, and it works fine.

You may find that integrating components that were designed for the studless system into a studful construction somewhat more of a hassle than you first expect - you often need half-stud offsets to get things to line up. Good luck!

[Grosse Kind]

Have obtained an 12 tooth bevel. Gear does not transmit torque in the application and skips horrendously. It actually makes the 14 seem good by comparison. Video below is in the highest of the three gears and it can't cope even with the low loads that that places on it.

Shall stick with my modded sixteen. Has the added advantage of not just curing the skip but with my other bracing, its higher gearing (motor-differential) continues to allow first to be used.

Not that the 12 was a large investment, but would have been nicer to know it was not suitable beforehand. May add it to a centre diff in 14-12-14 config as like AllanP stated, the gears when mixed form an LSD, (even if the configuration is reversed) but its otherwise superfluous in the interim.

[DrJB]

You're right. It sounds really bad. The old differential and the relatively new 12-tooth gears are 'generations apart'. Thus, I am not sure the teeth profile (and axis spacing) were meant for them to mesh properly. The image below 'states' that the teeth/dimensions of old differential were designed for it to mesh with the old 14-tooth gear (same as those inside the differential). I am not sure offsetting the differential (left-right) is even possible.

I got the above picture from a thread here on EuroBricks

http://www.eurobrick...showtopic=76320

Edited February 17, 2015 by DrJB

[Grosse Kind]

The 14 would make a fair grasp of things and at least carry the can in second and third, but first was a hit and miss affair. After bracing the trans and output shafts, the strength was there for the ratio and no further gearbox drama's ensued. I wouldn't consider the standard 8860 box great as designed.

But at 6:1 overall and those four big square slugs, the crownwheel and pinion became the new ratcheting point vs load. After waiting 25 years to own this set, amended instructions with the lockout on first or not, i was going to have three working ratios. I have that now, reliably, but its not original or pretty though is done with all period pieces.

Might start a new thread see what others have done to get around it.

[Captainowie]

Oh, sorry, that was partly my fault. When I said that "it works fine", I was reproducing the picture you had posted. Reading your post again I see that you meant using the old diff with the new gear.

Once again, sorry.

Owen.