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Interlock Gear Design for Part Adjustment 2

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jnelson33

Mechanical
Mar 7, 2018
53
**DISCLAIMER: I am not looking for the true knitty-gritty, science-the-sh@t out of this explanation, only the common sense, yes or no, this is a good design, here are some pointers explanation.**

Hello All,

I am making a geared-locking part for use on vehicles in all sorts of driving conditions. In order to help some of our products mount on tube chassis vehicles, they will need a clamp. The varying diameter clamp fastens to the tube on the car, in between that are two geared halves followed by the bracket for the part fastening to the clamp. The fastening is all done via one Grade 12.9 alloy steel ISO 4762 M8x1.25 socket head screw. The primary part is connected to that bracket/gear/clamp assembly.

I have provided a rough picture for how this will generally look. In real life, the correct M8 screw will be used without that long spacer. The idea is that the diecast geared halves allow for adjustment of our part on the tube chassis vehicles so that they can be made level again.
IMG_6176_f887db.jpg

IMG_6176_3_x0lsmi.jpg


Another company has done something similar to this, but I can't stand making parts to 50 year old CNC/manufacturing standards, plus all that drilling and pressing of pins is just insane when not needed! This is what my boss wanted me to copy, but I knew it wasn't a good way to make things.
IMG_6176_1_htcpbj.jpg

IMG_6176_2_webvzh.jpg


My boss does not believe the gear design that I have made will keep it locked since the teeth don't make contact along the whole face, a decent point of course, but one I believe to be insignificant for this application. His other comments are, "...need to tweak the CAD model and prints for this to square off or round off the sharp edges of the gears so that we can send this off for quoting as a die cast part." His background is software engineering, so that's why I'm here; I need to bound this off some more appropriate internet colleagues since my discussions with him just end in my way or the highway.
IMG_6176_4_xahbw3.jpg


Btw, my idea was inspired by my drumming hardware. My boss does like that the "faces mesh fully" on those parts; what gear standard do y'all think this is loosely based on, I thought face spur gears which led to crown gears?
Teeth_ltzeht.jpg


I searched for a while when I first tackled this design, and found the crown gear design that I'm using now. The only problem I see with the design I used is that it's designed for propulsion which is why the insides don't mesh.
Link
IMG_6176_5_lhvopl.jpg
 
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JNelson33 said:
what gear standard do y'all think this is loosely based on

None.

It may look like a crown gear, but it's not. Parts like that are designed so that they have as much face contact as possible.

Gears require clearance in order to function- but clearance is not what you want if your goal is to lock parts together in a repeatable way.
 
That idea goes waaayyy back. Jota (1960's) motorcycle handlebars had them for adjustment.
Here's some aftermarket ones:

Jota bars

Not as beautifully made as originals...

www.tynevalleyplastics.co.uk

Politicians like to panic, they need activity. It is their substitute for achievement.
 
No, this is not a good design, here are some pointers explanation:
-point contact - virtually no load carrying capacity
-sharp edges - will cause nothing but troubles

Here's some info on designing the Hirth couplings:
 
spigor said:
No, this is not a good design, here are some pointers explanation:
-point contact - virtually no load carrying capacity
-sharp edges - will cause nothing but troubles

Here's some info on designing the Hirth couplings:

Thanks for your input, and for a decent piece of literature spigor; I'm glad you knew about this technology that uses a similar style of teeth to those in my drum hardware!

I thought of the aspects you brought up myself when designing the part too, but figured since they'd be fastened together it would be alright with only partial contact. I mean, you can screw two flat plates together tight enough and they won't rotate easily, even with impulse, but I can see where the drum hardware design is initially better due to the increased face contact, and non-sharpened teeth.
 
Tmoose said:
What secures gear 1 to the bracket/lever, and what secures the half clamp to gear 2?

I've posted an edited picture that shows what holds the gear captive. This is an older design, so the legs will be revised to be filleted where the smaller cylinders meet the larger face to keep it stronger. Both gears would have these pins.
IMG_6176_3_za4f26.jpg
 
jgKRI said:
None.

It may look like a crown gear, but it's not. Parts like that are designed so that they have as much face contact as possible.

Gears require clearance in order to function- but clearance is not what you want if your goal is to lock parts together in a repeatable way.

Ok that makes sense for sure, and since I did take that crown gear design from the motion transfer world, I did tweak it to increase contact in certain areas, although not completely by any means. Maybe I can rework this design enough, and remove the parabolic inside profile which should make it easier to make too.

I understand all that stuff about gears, generally, I just forgot to state that it was intended to be a modified or inspired design in the first place, but I didn't want to deviate too far from what I figured should hold well.

Do you have a suggestion on a general direction or part that uses a traceable standard?
 
Pud said:
Jota (1960's) motorcycle handlebars had them for adjustment.

Do you have a name for the gear though? I searched briefly, but they just look like a pseudo crown-bevel gear, right? Those types of "gears" just seem like they'er more custom for sure.
 
These are used to connect the two halves of a pedal/arm assembly on some high end road bicycles. Look up a Campagnolo Ultra-Torque crankset connection. It looks like your sketch but with the roots and tips truncated.
 
Indeed - in fact it has a perfect photo of a Campy Ultra-torque crankset!
 
@3DDave
A curvic coupling has curved tooth line, while a Hirth coupling has straight tooth line.
 
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