Align Ring & Pinion Gears

[scott_browse]

Hello All,

I'm trying to setup joints and motion links between a ring (internal) gear and multiple pinion gears. If the pinion gears are on the on the x or y axis the ring an pinion align correctly (see attachements). If the pinion is say at a 35 degree angle to the y axis the gears don't line up.

I understand I can manually rotate the joint to align it but is there an equations to determine the correct adjustment angle so the gears mesh correctly?

See attachements.

Thank you,

Scott

Forgive me if my terminology is incorrect.

[Drewpan]

Hi,

There is no way I know that you can just punch in a number and the gears will automagically mesh. When setting up

motion links and such you would normally check for interference and manually clear the interference. Then you would

use the equation to motion link the motion.

An example. If I have three gears with 12 teeth, 24 teeth and 36 teeth then I would mesh the teeth manually and clear

the interferences. Then I would set up a motion link so that if the 24 gear turns one revolution then the 12 gear turns

two. I would set up a similar motion link for the 36 gear. This will work with gears in a single plane and may work with

other orientations. Gears meshing in one plane are fairly straight forward but gears meshing in more than one plane

may mean adjusting the shape of the gear teeth to make it work.

If you start meshing gears at angles then you may need to play with the actual equations to design gears, that is a

whole different story. I don't know how many engineers create custom gears from scratch but all of the ones I know

will typically use some kind of online calculation tool. It will then depend entirely what the requirements are in terms

of custom design for meshing, backlash and other factors.

Remember that you are only modelling with fusion, real world will always need some adjustment.

Cheers

Andrew

[MRWakefield]

I would expect the pinion(s) would need to be rotated according to the ratio between the pinion in question and the ring gear multiplied by the fraction of the ring where the pinion is positioned. I'm not sure I explained that very well so if you can attach your f3d file it gives us something to play with.

[davebYYPCU]

Top pinion and ring gear are aligned.

Draw a sketch line from the Botton midpoint of a ring gear valley to the centre of the system

measure that angle.  Set second pinion gear on that radial line, rotate the gear in the joint dialogue box, by the measured angle.

(might not be exactly 35 degrees due to ring gear spacing)

Might help….

[evanp4509U4JZ]

I don't have gears handy to try but if you make a contact set wont the gears align through the contact set?

[scott_browse]

@Drewpan

Thank you for your reply. I have setup motion links and set the rotation to be (72/24) * 360 deg. The motion links work but unless I set the "Alignment Angle" on the joint to -10.0 deg the second pinion teeth are not align correctly.

[scott_browse]

@MRWakefield - Thank you for your reply. I've attached my 3fd file for review. If I manually rotate the "Alignment Angle" on the 24 tooth pinion gear -10.0 deg it lines up but that just by eyeballing it.

[scott_browse]

@evanp4509U4JZ - Thank you for your reply. I will look into the contact sets, not something I've used yet.

[scott_browse]

@davebYYPCU - Thank you for your reply. I'll give that a shot.

[HughesTooling · Accepted solution]

It looks like a fairly easy why to calculate would be 90° minus the 35° angle of the setup sketch will give the correct rotation, as it's rotated clockwise it needs to be -55°

[jhackney1972]

You need to align the teeth on the second set of gears manually then when you start the Motion Link, be sure and Capture Position and then continue with your ratio.  Model is attached.

[HughesTooling]

After wasting way too much time I found with these gears you need to rotate the 24 tooth gear -2*the angle of the line in the sketch. Not sure why, I thought it should be 72/24 but that didn't work. In the attached file you can edit the AngleFor24Tooth parameter and the gears will align correctly. I also added the motion link.

[scott_browse]

@HughesTooling & @jhackney1972
Thank you both for your solutions both appear to work for the 24 tooth gear.

I liked the solution of 90 - 35 for a -55 deg setting and it worked perfectly for the 24 tooth gear. I added a 3rd gear with 42 teeth directly opposite of the 24 tooth gear at 145 deg and the math doesn't seem to work. There must be some other factory most likely regarding the size of the gear.

I've added another f3d file with the 3rd gear if you'd like to take a look. I eyeballed the 3rd gear with a .75 deg Alignment Angle in the 3rd gear joint. Just wish there was a mathematically way to do this vs. eyeballing.

Really appreciate  all the help!!!!

[davebYYPCU · Accepted solution]

Just wish there was a mathematically way to do this vs. eyeballing.

There is, for this gear it's -145 degrees.  (90 + 55)

Measured from Component X axis, to the 35 degree line.  -145 degrees, use that number.

The tooth sketch aligns with X axis.

[scott_browse]

@davebYYPCU

Wow... I feel really stupid. Is it really as simple as setting the "Alignment Angle" on the joint to angle of the of the line on my sketch? Does this only work because the ring's root surface is at 90 degrees?

Setting 24 tooth pinion @ 35 and the 42 tooth pinion @ -145 works perfectly.

[davebYYPCU]

Well, not so simple, imagine a gear with odd number of teeth.

There will always be an initial tooth, before patterning, so you find that tooth, then you measure where to put it when making the Joint.  It has to align with a tooth socket, on the radial line.  

Not many people realize how much value the Component and File Origins work so nicely for round objects.

Might help...

[HughesTooling]

---

@davebYYPCU wrote:

Well, not so simple, imagine a gear with odd number of teeth.

There will always be an initial tooth, before patterning, so you find that tooth, then you measure where to put it when making the Joint.  It has to align with a tooth socket, on the radial line.  

Not many people realize how much value the Component and File Origins work so nicely for round objects.

Might help...

---

Going off this, if you start in a place where the ring gear and the pinion gear align. So for this 72 tooth ring gear and a 25 tooth pinion that would be at 3 o'clock. Then use the angle from there you can calculate the rotation of the pinion using the (number or teeth on the ring gear divided by the number of teeth on the pinion - 1) x the angle from 3 o'clock.

In the attached file the 25 tooth gear doesn't have the correct module so doesn't quite mesh but the rotation of the gear's joint is correct.