Choosing a brake for multiple wheel system 4

[SR71-110]

Hi All,
A quick question about Brakes, if I need to use one brake for different size wheels. Is it feasible? If yes, if anyone can guide me in the right direction, I would really appreciate it.

Thank you.

 

[Jboggs]

You haven't provided near enough information for a valid answer. More details please.

 

[SR71-110]

It's for testing wheels of different sizes, tested on a rotating drum (WHEEL ENDURANCE TESTING). To find the slippage in the x direction where the wheel contacts the drum

 

[Jboggs]

That's nice but you haven't told us anything about any parameters. Sizes? Speeds? Materials? Forces? Type of brake? Duty cycle? Thermal considerations? Application? Test limits?

Is it feasible? Maybe.

 

[IRstuff]

Brakes are typically sized for the braking load; change the braking load without changing the brake and brake performance will vary, since that's intimately tied to the heat dissipation and ablation of the brake pad.

Braking performance would obviously vary if I had my empty Prius vs. loading it down with 500 lb of fertilizer.

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[dvd]

Braking may easily be done through the vid on a drive motor. Just depends on energy absorption - i.e., system kinetic energy = brake work

Maybe you’d want an emergency brake. Falk makes couplings that can be coupled with brakes. No doubt other options for brake couplings.

Have you searched for ASTM/EN/DIN standards on this type of test and testing equipment?

 

[SR71-110]

@dvd
Yes, I searched for it, but I couldn't find anything about brakes.
did you say Vfd or vid? on a drive motor? I am not sure if I understood. Are you implying that a brake can be used in conjunction with the drive motor? I am powering the drum with the motor which turns the wheels.

 

[IRstuff]

You can load the unpowered motor windings which will dissipate the energy that is being generated by the motor spinning mechanically. which slows down the assembly

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[Gr8blu]

There are essentially two types of brakes: ones that are intended to produce the entire braking force, and ones that aren't. In the first case (e.g. entire braking force), knowledge of a lot of inter-related details is required (see JBoggs' post above). That being said, pretty much guaranteed a given brake is good for a range of application. In the second case (e.g. partial braking force), we have the same thing - but here you need to know how much braking force needs to be applied (i.e. 20%? 40%? 60%? of the actual total needed for a "full brake" approach). In the second case, another common term used is the "holding brake", where the idea is to keep the unit from moving once it's stopped (or to cause a complete stop from a very low rotational speed (few revolutions-per-minute).

With power electronics (e.g. a variable frequency drive) as an electrical source for your motor, you might have what is called regenerative braking capability. In effect, when "braking" the motor dumps electrical energy back into the drive which is then routed through something (most often, some sort of resistor) and heat is released. These types of drive are also called "4 quadrant" drives, since the ability to rectify power must cover all directions. These drives are a bit more expensive than the "cheap" drives used for non-regenerative applications.

Converting energy to motion for more than half a century

 

[BrianE22]

A disk brake on the drum would probably be cheapest. You can vary the torque by adjusting the air pressure to the caliper. It's not super repeatable. The relationship between air pressure and torque might vary 10-20% (WAG) from day to day.

More accurate would be a hysteresis brake and closed loop torque control. You'd need a torque transducer to close the loop.

 

[dvd]

SR71... -

My vid should be vfd.

Not sure what braking you need, what is the intended purpose of the brake? Is there a specific stopping time/distance that is required? You could use a vfd-controlled motor to stop the load, it may be necessary to use a larger motor to provide a larger stopping torque if you require higher braking torque than driving/starting torque. You can use a brakemotor which provides a specific, spring-applied, braking torque. You can use a separate brake that is not part of the drive system. (You are probably not going to e-stop some high inertia load instantaneously, though.)

Are both the drum and wheel(s) powered? Why?

Do you work for a caster manufacturer, are you doing a garage project, something else?

The questions you are asking are fairly open-ended, and almost any answer is correct. Quantifying your problem will get you better suggestions.

A quick search revealed multiple standards, this was a reasonable summary -

https://www.tente.com/en-us/know-how/din-standards

 

[SR71-110]

@dvd
Thank you for your feedback.
I think DIN EN 12532 is the closest standard. Only think different is the brake addition to generate tractive force.
Only the drum is driven which drives the wheel, I need the brake applied to the wheel to generate a tractive force. I will be working with this I am just new to this.

 

[dvd]

It sounds as though you need a continuously-operating brake - tension-control brakes used in various industries are intended for continuous duty. See

https://www.forcecontrol.com/products/brakes/tension-brakes/

https://www.machinedesign.com/automation-iiot/article/21827678/tension-brakes-let-it-slide

A secondary drive system on the wheel(s) could be used to generate this type of braking, also.

 

[IRstuff]

Perhaps you should be looking at an eddy-current (magnetic), or similar, brake, since that provides a very consistent braking force.

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