Constant Mesh Gearbox Diagram

[dr_gn]

People,

Does anyone have a link to a clear diagram of a dog-clutch type constant-mesh gearbox?

I want to use it as a basis for an interview question on gear ratio calculations and general mechanism interpretation.

I´m trying to find a few questions and practical tests which will find practically minded degree qualified candidates for an R&D design engineer position.

Any other suggestions gratefully accepted.

Cheers,

[Conian]

i dont have one, but by commenting, i've moved you to the top of the 'whats new list' in the hope that someone else will see it and be able to help.
besides, i want to see the pic too.

[Sam_68]

I don't know if it'll give what you are looking for, but there are parts diagrams and workshop manuals for Hewland's gearboxes available on the company website.

[stevieturbo]

What is a dog clutch ? and what does the term constant mesh actually mean ?


I cant think of a gearbox where the gears arent always meshing anyway ?

[Sam_68]

stevieturbo said:

What is a dog clutch?

Face dog engagement, as opposed to baulk-ring synchromesh.

stevieturbo said:

I cant think of a gearbox where the gears arent always meshing anyway?

All modern geaboxes are constant mesh, but plenty of vintage 'crash' gearboxes actually slid the gears in and out of mesh with each other, rather than leaving them meshed all the time and simply locking them to the shaft to engage them.

[dr_gn]

Sam_68 said:

stevieturbo said:

What is a dog clutch?

Face dog engagement, as opposed to baulk-ring synchromesh.

stevieturbo said:

I cant think of a gearbox where the gears arent always meshing anyway?

All modern geaboxes are constant mesh, but plenty of vintage 'crash' gearboxes actually slid the gears in and out of mesh with each other, rather than leaving them meshed all the time and simply locking them to the shaft to engage them.

Loads of Machine tool gearboxes aren´t constant mesh either.

Thanks guys for the help. I think I´ll end up using modded versions of the rather unclear Wikipedia diagrams. I was after fairly basic schematics rather than actual gearbox diagrams / parts lists.

[stevieturbo]

Sam_68 said:

stevieturbo said:

What is a dog clutch?

Face dog engagement, as opposed to baulk-ring synchromesh.

stevieturbo said:

I cant think of a gearbox where the gears arent always meshing anyway?

All modern geaboxes are constant mesh, but plenty of vintage 'crash' gearboxes actually slid the gears in and out of mesh with each other, rather than leaving them meshed all the time and simply locking them to the shaft to engage them.

That has nothing to do with the clutch.

Wow...sounds nasty !!

[dr_gn]

stevieturbo said:

Sam_68 said:

stevieturbo said:

What is a dog clutch?

Face dog engagement, as opposed to baulk-ring synchromesh.

stevieturbo said:

I cant think of a gearbox where the gears arent always meshing anyway?

All modern geaboxes are constant mesh, but plenty of vintage 'crash' gearboxes actually slid the gears in and out of mesh with each other, rather than leaving them meshed all the time and simply locking them to the shaft to engage them.

That has nothing to do with the clutch.

Nobody said it was "to do with the clutch". It has nothing to do with dogs either, or cats or rabbits for that matter. Just like a brake caliper piston has nothing to do with an engine piston. It´s still a piston, just as a clutch is a clutch irrespective of how it operates or where it happens to be located.

And here´s me thinking the questions aren´t difficult enough.

[Sam_68]

stevieturbo said:

That has nothing to do with the clutch.

The definition of a clutch is simply a mechanism that allows drive to be engaged and disengaged.

The arrangement of dogs that lock the gears onto the shaft when they are engaged are themselves 'clutches' (dog clutches, obviously). If you're getting into hair-splitting semantics, the OP is therefore correct.

Of course they're not 'the' (main) clutch on the car, but your argument would be akin to saying that timing gears are not gears, simply because they aren't incorporated in the gearbox.

[dr_gn]

Sam_68 said:

stevieturbo said:

That has nothing to do with the clutch.

If you're getting into hair-splitting semantics, the OP is therefore correct.

Absolutely, but TBH I wouldn´t say I was correct due to "hair splitting semantics"...I asked for a diagram of a "dog-clutch type constant-mesh gearbox". How could that possibly be ambiguous?

* Surely * anyone with even a basic knowledge of car mechanics would know what that was without assuming I was talking about anything to do with clutch bolted to the back of the engine???

This is a perfect illustration of why I want to try and determine how practically minded a particular job candidate is. If even a simple question requesting info about the *real* interview question causes confusion, I´m screwed.

Edited by dr_gn on Saturday 5th June 19:47

[stevieturbo]

Generally that is simply called dog engagement, as opposed to dog clutch.

Same way you'd never hear of syncromesh clutch gears

[dan19evans]

hopefully this is the sort of picture you were looking for:

[dr_gn]

stevieturbo said:

Generally that is simply called dog engagement, as opposed to dog clutch.

If you don´t know what a dog clutch is, just look on Google, and you´ll see it fully explained in the first example on Wikipedia - a gearbox strangely enough.

If you know what it´s "generally" called, it´s strange you couldn´t link my request for info on a "Dog Clutch type" gearbox to your preferred name of "Dog engagement" gearbox, without asking what a dog clutch was, and for that matter asking what "constant mesh" was? All the other respondants to the question seemed to understand the question.

stevieturbo said:

Same way you'd never hear of syncromesh clutch gears

You do. There´s a full explanation of them here, fifth paragraph:

http://www.tpub.com/content/engine/14037/css/14037...

If you meant "synchromesh clutch gearbox" as opposed to "synchromesh gearbox" - if you can´t figure out they are the same thing...

Edited by dr_gn on Sunday 6th June 12:45

[dr_gn]

dan19evans said:

hopefully this is the sort of picture you were looking for:

Exactly, apart from you can´t easily figure out by looking that what they call the ´dog gear´ assemblies are keyed or splined to the output shaft. I could say that in a written description, but the idea was to let them figure it out from a diagram alone.

Thanks a lot, I might try to use that one instead of the Wikipedia diagram.

EDIT: There doesn´t appear to be a reverse gearn or a selector lever either.

Edited by dr_gn on Sunday 6th June 08:37

[dan19evans]

dr_gn said:

dan19evans said:

hopefully this is the sort of picture you were looking for:

Exactly, apart from you can´t easily figure out by looking that what they call the ´dog gear´ assemblies are keyed or splined to the output shaft. I could say that in a written description, but the idea was to let them figure it out from a diagram alone.

Thanks a lot, I might try to use that one instead of the Wikipedia diagram.

EDIT: There doesn´t appear to be a reverse gearn or a selector lever either.

Edited by dr_gn on Sunday 6th June 08:37

is this the pictture u were looking for?




hope that helps!

[Frik]

You've got a lovely way of asking for help, dr_gn.

Good luck with you picture hunt.

[stevieturbo]

dr_gn said:

stevieturbo said:

Generally that is simply called dog engagement, as opposed to dog clutch.

If you don´t know what a dog clutch is, just look on Google, and you´ll see it fully explained in the first example on Wikipedia - a gearbox strangely enough.

If you know what it´s "generally" called, it´s strange you couldn´t link my request for info on a "Dog Clutch type" gearbox to your preferred name of "Dog engagement" gearbox, without asking what a dog clutch was, and for that matter asking what "constant mesh" was? All the other respondants to the question seemed to understand the question.

stevieturbo said:

Same way you'd never hear of syncromesh clutch gears

You do. There´s a full explanation of them here, fifth paragraph:

http://www.tpub.com/content/engine/14037/css/14037...

If you meant "synchromesh clutch gearbox" as opposed to "synchromesh gearbox" - if you can´t figure out they are the same thing...

Edited by dr_gn on Sunday 6th June 12:45

I know exactly what dog engagement gears are.

I queried the term constant mesh, as Ive never heard or seen of a gearbox where the gears arent always meshed !! So seems odd to make reference to it, when every single car gearbox is like that.

As for syncromesh clutch gears.....you post one link. Still doesnt alter the fact virtually nobody refers to them as such.

And I queried dog clutch...as people make upm some very strange names for things, which often have no relevance to what they are trying to describe in the first place.

As you seem to be the rocket scientist here....its amazing you dont already have any pictures, as you seem to know everything about them.

[Pigeon]

"Dog clutch" is hardly "made up", it's been in widespread use for yonks.

[Zad]

I guess this is from the same source. The right hand one is what I would call a dog box:



http://www.carbibles.com/transmission_bible.html

[dan19evans]

Zad said:

I guess this is from the same source. The right hand one is what I would call a dog box:



http://www.carbibles.com/transmission_bible.html

yep same source