Posted by: warznorth ® 05/23/2006, 02:01:50 Author Profile eMail author Edit

Could you guys help me out with this? I need to know what this thing will lift and I cant wrap my head around the formula to figure it out, what is the formula?

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Re: Lever calculation
Re: Lever calculation -- warznorth	Post Reply	Top of thread	Forum

Posted by: zelgar00 ® 05/30/2006, 14:03:14 Author Profile eMail author Edit

The basis for Statics are the following 2 rules: #1 The sum of forces at any one point are equal to 0 (i.e., Sigma x = 0, Sigma y = 0 and Sigma z=0 at any point) #2 The sum of moments at any point are equal to 0

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Re: Re: Lever calculation
Re: Re: Lever calculation -- zelgar00	Post Reply	Top of thread	Forum

Posted by: warznorth ® 05/31/2006, 10:42:16 Author Profile eMail author Edit

You guys were right there is more to this than meets the eye, at first I tried calculating this as a class 3 lever wich I beleive is ok but not accurate, am I right.

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Re: Lever calculation
Re: Lever calculation -- warznorth	Post Reply	Top of thread	Forum

Posted by: zekeman ® 05/23/2006, 13:41:32 Author Profile eMail author Edit

This is not a DIY probject unless you are very familiar with statics. And it is a lot more complicated than meets the eye. You are talking at least 4 equations including the cutting of sections since you show two 4 bar linkages, etc. If you are still game and this is not a HW problem, perhaps we can guide you somewhat.

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Re: Lever calculation
Re: Lever calculation -- warznorth	Post Reply	Top of thread	Forum

Posted by: swearingen ® 05/23/2006, 07:06:51 Author Profile eMail author Edit

I'll call the rightmost pin of the 30,000lb cylinder Pt. B. You need to create an equation that shows the vertical load at Pt. B in terms of a variable load "P" at the end of the boom (Equation 1). Then you could use vectors to set up an equation for how much vertical force can be produced at Pt. B by the cylinder (Equation 2). Since you know the force the cylinder produces, you can directly calculate this value. Plug that value into Equation 1 and solve for P.

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Re: Re: Lever calculation
Re: Re: Lever calculation -- swearingen	Post Reply	Top of thread	Forum

Posted by: warznorth ® 05/23/2006, 08:15:28 Author Profile eMail author Edit

Do I need to account for the angle of the cylinder?

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Re: Re: Re: Lever calculation
Re: Re: Re: Lever calculation -- warznorth	Post Reply	Top of thread	Forum

Posted by: swearingen ® 05/24/2006, 09:13:03 Author Profile eMail author Edit

You absolutely must account for the cylinder angle. As I said before, break it into vectors at the Pt. B and the vertical vector portion of the 30,000 lbs, based on the angle, should be plugged into the equation you set up for P. I'm being intentionally vague because this reeks of a homework problem...

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Re: Re: Re: Re: Lever calculation
Re: Re: Re: Re: Lever calculation -- swearingen	Post Reply	Top of thread	Forum

Posted by: warznorth ® 05/25/2006, 10:47:32 Author Profile eMail author Edit

Ha thanks, be nice if I could find a calculator that would do the whole thing, once I get the formulas figured out I think ill program one so I dont have to go thru this again, My wife said this would be easyer if I went to engineering school.

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Lever calculation
Re: Re: Re: Re: Re: Lever calculation -- warznorth	Post Reply	Top of thread	Forum

Posted by: swearingen ® 05/25/2006, 14:41:13 Author Profile eMail author Edit

Just yesterday, as I was leaving work, I saw an arm that is proportioned and detailed almost EXACTLY like the one you have shown. The writing on the hub said: PRENTIC F90. Where did you get the drawing you have and what will it be used for?

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Re: Lever calculation
Re: Lever calculation -- swearingen	Post Reply	Top of thread	Forum

Posted by: warznorth ® 06/09/2006, 11:53:43 Author Profile eMail author Edit

I found the software to solve my problem its from (Design Simulation) and its called Working Model I downloaded the trial version then imported my design data ran the simulation and got my loads, it was simple Modified by Administrator at Fri, Jun 09, 2006, 13:57:03

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Re: Re: Lever calculation
Re: Re: Lever calculation -- warznorth	Post Reply	Top of thread	Forum

Posted by: Kelly_Bramble ® Administrator 06/09/2006, 14:06:06 Author Profile eMail author Edit

Design Simulation's software is very pricy for what it does, you do the same sumulation with almost any CAD software on the market. Additionally, a simple pop-stick model is just as helpfull. Warznorth, who do you work for?

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