gearboxes

[Simon_T]

Today I've been looking through my boxes of gearboxes and decided to label up the boxes for future reference. Ive been looking at stickys book and the references made to loose gears in respect of measurements of pitches etc, so i got my vernia gauge out and started measuring only to find most didn't come close to the figures in the book.
Ok so I've counted the teeth and matched the loose gears that way but the measurements through me out at some point.
Could someone explain to me where i measure the distance from to match the book reference also some loose gears have same teeth but different pitch, would these be compatible across the range if used in conjunction with the similar gears.
thanks in advance.

[hullygully]

if you place the vernier across a couple of teeth top & bottom, then you should get a size thats real near to the book size, so there's also a tolerance of say
+/- 0.3mm????
& the question of 'can you mix & match' ? all depends on the xmas tree................has that the same pitch as the loose gear?

[Warkton Tornado No.1]

Sticky’s book is what I tend to use so your posting has made me wonder what the problem is.

Sorting through your gears, must have resulted in piles of gears of an identical generic design, in bore, faces so that you could tell first from second, from third.
The measurement Sticky refers to as:

LOOSE GEAR DIAMETER ± 0.2 mm

is the outside diameter. That is easy to check on even number of teeth, ‘near enough’ on odd.

The only other dimension that I think can be causing you any other confusion is the span relative only to third gear checks.

I don’t think that there are any pitch dimensions whatsoever to cause anyone confusion. In any case, Innocenti base gears are based on a modular format but with bastard PCD’s in most instances.

Perhaps you could post photos with your vernier caliper in place?

I hope to have helped.