What is the formula for calculating force in a crank and slider mechanism?

In summary, the individual needs to calculate the amount of force needed to fold the two plates at a specific angle, based on the mass of each plate. The force is non-linear, and becomes easier to lift as the angle gets closer to 180 degrees.
  • #1
ShaiNaveh
5
0
Hi all,

I have a question regarding a simple crank and slider mechanism, but I'm not a mathematician. This means that long formulas scare me... (: I've been searching around and haven't found anything I can really understand.

I'm trying to get a "ball park" formula to calculate the amount of force I'll need to push plate B at a given angle between the two plates in order for them to fold. I suppose that when the angle is 180 deg., no force would do the trick, but at 0 deg it would be the easiest. I'm also sure it's not linear, but that's as far as my knowledge takes me for this kind of linkage...

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For this example let's say the the plates weigh 1kg each, and there is no friction involved. It's probably something you guys blurt out in your sleep, for me it's voodoo...Any help would be appreciated.

Many thanks, and happy September 1st holiday for us parents... (:
 
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  • #2
Lengths of the plates?
 
  • #3
Bystander said:
Lengths of the plates?
Ohhh dear, you're right, that IS important... It's 0.5m each.

Thank you.
 
  • #4
Are you familiar with trig functions?
 
  • #5
Bystander said:
Are you familiar with trig functions?
The basic stuff I suppose
 
  • #6
Give you any ideas?
 
  • #7
Bystander said:
Give you any ideas?
Not sure I understand what you mean...
Do trig functions give me any ideas, or are you asking me if I want you to give me any ideas...
 
  • #8
ShaiNaveh said:
Do trig functions give me you any ideas
 
  • #9
Yes, they give me an idea, but only an idea regarding the non-linear fashion of the force I need. As I said, I have a real problem with understanding formulas, all the way back to my school years. I've been designing and building machines for years using my experience and gut feeling when it comes to selecting motion components. So far nothing has crashed... but sometimes my gut feeling is not enough and I need to go back to school.

The way I see it, the mass is centered in the pivot. It should be half of each plate's mass when the angle is 180 deg., so there's 1kg to lift there. I also know that the pivot point gets easier to lift in a non-linear manner. It should be half the mass at 60 deg. if I'm not mistaken.
 

1. What is a crank and slider mechanism?

A crank and slider mechanism is a mechanical linkage used to convert rotational motion into linear motion. It consists of a crank (rotating arm) and a slider (moving arm) connected by a rod or link.

2. How does a crank and slider mechanism work?

When the crank rotates, it causes the slider to move back and forth in a straight line. The amount of linear motion is determined by the length of the crank and the angle of rotation.

3. What is the purpose of a crank and slider mechanism?

Crank and slider mechanisms are commonly used in engines, pumps, and other machines to convert rotational motion into linear motion. They are also used in toys, such as pull-back cars, and in steering systems for vehicles.

4. How does the crank length affect the linear force of a crank and slider mechanism?

The longer the crank length, the greater the linear force produced by the mechanism. This is because a longer crank creates a larger rotational distance, resulting in more linear motion.

5. What factors can affect the efficiency of a crank and slider mechanism?

The efficiency of a crank and slider mechanism can be affected by factors such as friction, wear and tear, and misalignment of the crank and slider. Regular maintenance and proper lubrication can help improve the efficiency of the mechanism.

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