Question on centrifugal brakes

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    Brakes Centrifugal
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Discussion Overview

The discussion revolves around the design and specifications of centrifugal brakes, particularly in the context of a weight-lowering mechanism for a system with a mass of approximately 1000 kg. Participants explore the general values for the friction coefficient, mass of brake shoes, and spring constant, while clarifying the operational principles of centrifugal brakes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant requests general estimates for the friction coefficient, mass of brake shoes, and spring constant for centrifugal brakes used in a weight-lowering mechanism.
  • Another participant seeks clarification on the term 'centrifugal brakes', suggesting it may refer to an automatic system like a 'flyball' governor, and notes that the specific mechanical device would influence the values needed.
  • A participant provides a link to a diagram of a braking system similar to the one being discussed, explaining that the centrifugal brakes would use brake shoes and pads to stop the rope drum when it rotates too quickly.
  • One participant expresses unfamiliarity with this type of elevator safety system, noting they are more accustomed to systems that clamp onto side-rails, and acknowledges the idea but cannot provide assistance.
  • Another participant mentions that centrifugal brakes are commonly used in emergency systems, such as in mine cages, but raises concerns about overheating and potential seizing due to increased braking force.
  • The original poster thanks participants for the information and indicates they will modify their design based on the feedback received.

Areas of Agreement / Disagreement

Participants express varying levels of familiarity with centrifugal brakes and their applications, leading to a lack of consensus on specific values and operational details. Multiple competing views on the effectiveness and design considerations of such systems remain unresolved.

Contextual Notes

Participants highlight the importance of the specific mechanical design and operational conditions, such as load and braking mechanisms, which may influence the values and performance of the centrifugal brakes. There are also concerns about heat generation and its effects on braking efficiency.

enkiduz190
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hey guys, i was wondering if any of you know the general values for the friction coefficient as well as the mass of the brake shoes and the spring constant for the centrifugal brakes (i know there are probably all sort of values, but please just give me a general rough estimate)? The brake is going to be incoporated in a weight lowering mechanism of about 1000kg.

i tried to search for it, but can't find anything, so if anyone has knowledge in this field, please give me a rough estimate on the values, really appreciate it.
THANKS a lot!
 
Last edited:
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Welcome to PF, Enkiduz.
I won't be able to help with any calculations, but I just want to clarify what you mean by 'centrifugal brakes'. I've never heard that term. Do you mean some sort of automatic system such as the 'flyball' governor on a steam engine that stops something when it goes too fast?
In any event, the sort of mechanical device involved would make a big difference to the numbers. While you mentioned how much weight is involved, we don't know what mechanism is doing the work. For example, is it hydraulic, or pulleys and cables, or...?
 
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http://science.howstuffworks.com/elevator5.htm
the braking system i am working on is very similar to the one they have in the diagram, except that instead of using a hook, the centrifugal brakes uses brake shoes and brake pads to stop the rope drum from rotating when it goes too fast.

the braking system i am working on works like this:
the rope drum have cable which connect the lowering platform, if the platform falls too fast, then the centrifugal force will force the brake shoe and the brake pad out, thus stopping the rope drum.
i hope this provides more information as to what i am looking for. thanks guys
 
I know what you mean now. I've never seen that sort of elevator safety before; I'm more used to the ones that clamp onto the side-rails.
So your idea, it would seem, is to have the same governing system as the one depicted, but with less 'g-load' upon braking. That's a pretty cool idea, and I wish you the best with it. Unfortunately, that doesn't imply that I can help you.
 
It's a common system on things like mine cages - usually as an emergency system if the motor controlling the cable drum fails.
The problem with using it as the sole speed control is that the brakes heat up and so tend to expand, so putting in more braking force and so more heating - and so on until they seize on.
For lighter load systems like autodesceding abseiling lines you use a fan rotating in a housing and let air ( or oil ) resistance slow it down so it is easier to dump the waste heat.
 
Thx for the info, i will now modify the design accordingly.
 

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