Lengh to depth ration of a sliding element? 2

[Mattsudd]

What is the ratio of lengh to breadth/depth of a sliding element, that ensures that the element will not stick whilst sliding? In German there is a formulae called the schublade formulae (draw formaule). For example, an old chest of drawers, when you pull the drawers out, if you dont pull the draw out stright it gets stuck. Is there a norm or ratio to ensure that this does not happen!

Any help will be great.

Thanks

 

[zekeman]

The tangent of the angle between the two sliding elements should not exceed the coefficient of static friction.

 

[Mattsudd]

Thanks for the help. Can you give a referance to that from a book or web page, that would be excellent.

 

[swearingen]

Put some math to it. You can work it out from first principles. Go ahead and bang it out - when you see it on paper, you'll have one of those A-HA moments...


If you "heard" it on the internet, it's guilty until proven innocent. - DCS

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[eromlignod]

An old rule-of-thumb is about 2:1.

Don
Kansas City

 

[zekeman]

I couldn't find the literature you requested but it is a fairly academic problem, like, for example, take a broom (or rod) and push on it under tension at increasingly larger angles until it just stalls. Write the free body forces including tension in the broom, normal force from surface and friction force; when you satisfy the two equilibrium equations you will get the answer
If this doesn't help, then I will make it clearer.

Swearingen,
It may be that the OP doesn't have the grasp you have and may need a little help before "banging it out".

 

[hydtools]

Zekeman, that's confusing. How do you push on a rod under tension? Doesn't push create compression? Pull to create tension?

Ted

 

[zekeman]

Sorry, I got carried away. I meant compression.

 

[chicopee]

The angle that Zekeman is alluding to should not be more than about 6 degrees. Get a book on" Statics and Dynamics" on this subject. This is a fundamental question for any ME during their second year of college.