# Rotary Mechanical Brake System

1. Feb 24, 2017

### Jameseyboy

Hi,

I am looking into a braking system which can limit the rotational speed of a platform; the assembly consists of a fixed vertical shaft and a rotating outer tube (seated with bearings). The platform diameter is >5 times larger than the tube.

I have looked into the typical band brake, friction brake, etc however, there is a problem:
The limit on rotational speed is set at 1 RPM, so to generate a relevant braking force centrifugally is unrealistic (considering the mass is over 200kg).
The only concern with electronically assisted brakes is the safety factor.

My only other option would be rotary dampers but if anyone has any better ideas, that would be great.

Cheers!

Last edited: Feb 24, 2017
2. Feb 24, 2017

### Work Hard Play Hard

What's the function of the design and how integral to the function is the 200kg's? I'm thinking of some of the recent engine flywheel designs where the constant mass of the flywheel has been replaced by a magnetically induced mass. With this design you can brake at a different mass then the operational mass.

3. Feb 24, 2017

### Jameseyboy

The 200kg is basically the mass of the plate + its loaded elements.

Are you talking about eddy brakes? I understand they can be calibrated such that they are applied at a particular speed and effectively maintaining it.

I am going to need to back everything up with calculations so the simpler the better.

4. Feb 24, 2017

### Work Hard Play Hard

I would keep the brakes as simple and uncomplicated as possible since you have not yet identified a function for the device. What would the weight of the tube be if it was made of carbon fiber?

For the magnetics look first at trains that run by levitation. Do a search for magnetic flywheels and the internal combustion engine.

5. Feb 24, 2017

### Jameseyboy

When the disc rotational speed reaches 1 RPM, it needs to be capped but with smooth deceleration.

The materials are steel and cannot be changed. I'll do some more research on magnetic brakes. I do have a little room to play with; my shaft is around 5cm radius, and my inner tube is around 16cm radius.

Cheers

6. Feb 24, 2017

### Nidum

What is causing the platform to rotate ?

7. Feb 24, 2017

### Work Hard Play Hard

Fair enough but that's not where I was going with my response. Your braking difficulties are due to the mass of the tube. If you cant change the tube is the tube on a clutch? What's the power source? Is brake dampening required?

8. Feb 24, 2017

### Staff: Mentor

Is 1 RPM a hard limit, such that transient overshoot to 1.01 would be a disaster?

It is not clear whether you are asking about a breaking mechanism of about the control system to apply the brake.

9. Feb 24, 2017

### Work Hard Play Hard

I see you edited your original question which raises even more.

As already asked what is powering the platform rotation? What's the potential RPM of the platform without the brake? Is it safe to assume your goal is to use a brake as a governor? If so, does the governor have to be a brake?