Help, Need to calculate braking force? PLEASE HELP

In summary, the conversation is about a student seeking help with calculating the forces required for their university project involving a trolley. The trolley weighs 1687 Newtons and has a force of 98.1N from a spring pushing a rubber pad. The trolley travels at 4mph and requires 27N of force to move forward on level ground. The discussion includes suggestions for calculating the force of friction needed to stop the trolley and determining the pressure needed to activate the braking system. The conversation ends with the student asking for further clarification on the topic.
  • #1
a_u_nscopio
3
0
Hi guys, I am new to this forum, but I am in desperate need of help on something for my Final year university project. I have designed a Trolley and need to calculate some forces.

Does anyone know the formula to calculate the pushing forces required to stop this trolley from moving.

Weight of trolley is 1687 Newtons
the force of the spring pushing the rubber pad 98.1N.
The trolley is traveling around walking pace, 4mph.
Force required to move trolley forward is about 27N on level ground (road)

So currently 98.1N are pushing on the Pneumatic wheel, but I am not sure whether or not this force is strong enough to prevent trolley stopping when in motion.

It is a standard pneumatic wheel, with 50mm wide rubber material. The width of the rubber pad is 50mm x 50mm.

Is is possible to calculate the force of friction required to stop the wheel from spinning. The pneumatic wheel has textured rubber, as does the pad, which probably increases friction.
The pads act on two wheels.

[PLAIN]http://img714.imageshack.us/img714/1829/trolley1.jpg [Broken]

[PLAIN]http://img38.imageshack.us/img38/2768/trolleyv.jpg [Broken]

Thanks!
 
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  • #2
I am not sure if I can help you as I am only familiar with disc and band brakes. This was my thought process on your problem.

But you wheel will have a normal reaction to oppose the weight of the trolley. So there will be an associated rolling friction with that which will act in the same direction as the braking friction.

If you can find the torque needed to make the trolley move at 4mph, you can do a torque balance on the wheel:

Tpushing-Trolling-Tbrake=0, where you can get Tbrake and hence Fbrake.

So you can get the pressure needed to activate the braking system.
 
  • #3
rock.freak667 said:
I am not sure if I can help you as I am only familiar with disc and band brakes. This was my thought process on your problem.

But you wheel will have a normal reaction to oppose the weight of the trolley. So there will be an associated rolling friction with that which will act in the same direction as the braking friction.

If you can find the torque needed to make the trolley move at 4mph, you can do a torque balance on the wheel:

Tpushing-Trolling-Tbrake=0, where you can get Tbrake and hence Fbrake.

So you can get the pressure needed to activate the braking system.



Hi thanks for you help, I forgot to mention, I carried out some testing, and the force needed to push the trolley was about 27N on level ground (road).
 
  • #4
a_u_nscopio said:
Hi thanks for you help, I forgot to mention, I carried out some testing, and the force needed to push the trolley was about 27N on level ground (road).

That would be your resultant force. So 27=Fpushing-Frolling friction
 
  • #5
rock.freak667 said:
That would be your resultant force. So 27=Fpushing-Frolling friction

Again, thanks for your help. I'm still not quite sure, I am a design student, so my engineering skills are quite bad. Could you perhaps elaborate some more? Thanks
 
  • #6
a_u_nscopio said:
Again, thanks for your help. I'm still not quite sure, I am a design student, so my engineering skills are quite bad. Could you perhaps elaborate some more? Thanks

If you ignore the wheels for the moment, the force you found would be the resultant force. So if you use the equation

Resultant force =Fpushing-Ffriction

and find Fpushing, this will be the total force needed to push.
 

1. What is braking force?

Braking force is the force that is applied to a moving object in order to slow it down or bring it to a stop.

2. How is braking force calculated?

Braking force can be calculated by multiplying the mass of the object by its acceleration.

3. What units are used to measure braking force?

Braking force is typically measured in units of Newtons (N) or pounds (lbs).

4. What factors affect the amount of braking force needed?

The amount of braking force needed depends on the mass of the object, the speed at which it is moving, and the coefficient of friction between the object and the surface it is moving on.

5. How does braking distance relate to braking force?

The braking distance is directly related to the amount of braking force applied. The more braking force that is applied, the shorter the braking distance will be.

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