Member postings for John Lintorn

So it seems a 44T 6.D.P parallel depth tooth, Crown wheel, to the dimensions specified does not exist?

And as Jason says, on an odd number Crown wheel, the pinions will be in opposite positions which will match up with the opposite Crown wheel?

So I can use my plan of a 37T Crown wheel?

John

Andrew,

"You need to set the outer DP to 6 and then work out what the DP will be at the inner edge."

Any idea how I go about this haha?

Regards,

John

Thanks Jason, unfortunately the article does not explain how the Crown wheel can have 44T and still be the correct size.

Regards,

John

Andrew,

The design calls for 2 pinions exactly diametrically opposite.

Why does the Crown wheel have to be divisible by the amount of Pinions?

So I am only able to cut the bevel gears using the parallel method in Ivan Laws book. And using his procedure, 44T Crown wheel doesn't seem to fit the design?

Cheers,

John

Edited By JasonB on 22/10/2020 11:44:35

Hello!

I am just at the point of machining the bevel gears for the 3" Fowler.

I am using Ivan Laws Gears and Gear Cutting for all terminology and calculations.

I will be cutting the gears using Ivan Laws parallel depth method on page 106-111

Now H.R Plastow calls for a 44T Crown wheel and 9T Pinion both 6D.P.

This gives a P.C.D of 7.333"

The problem arises when you look at the distance between the backs of the Pinions. This is stated as 7.969"

Now the P.C.D can't be referring to a True Bevel Gear (True P.C.D of wheel as stated by Ivan Law page 46) as this would make the O/D of the Crown wheel far too small. It also can't be referring to Parallel depth Bevel gears (P.C.D of small end page 106) as this would mean the tooth face is only 5/16" long!

If I use N/D.P I find that 37T gives a small end P.C.D of 6.166"

This allows a tooth face of 0.86" and an O/D of 7.953, which is pretty much perfect for the Distance between the backs of the pinions.

My question is am I missing something here? Is 44T correct and I am being stupid or did Plastow get something wrong and my 37T is correct? I have seen the other thread referring to Bevel gears and ensured I Have changed the Sin to Cos where required but I still get the same result.

Help would be appreciated before I make a lot of cast iron mess!

John

Hi!

3" scale Fowler.

Part way through building my 3" scale mechanical lubricator to H.R. Plastows design and just wondering what the flow rate should be?

At the moment it delivers 1 drip every 10 turns. I've included a quick youtube video of the test.

https://youtu.be/64AHnONUuIg

I may invest but for now I just need a picture to show the top of the cylinder block so that I can see it in my minds eye