Main Question or Discussion Point

At work we have very heavy carts. The floor is in terrible shape. Management knows that they need to fix the floor but don't know if it will be cost effective. I.E. money spent on floor vs. increased production.

I want to make a spreadsheet. I don't know the math and I need your help.

I want to have 3 variables

The mass of the cart. the diameter of the wheel, and the size of the bumps on the floor will all change. I want to find out how many Newtons it takes to push this trolley.

M mass

D dia of wheel

H height of bump on floor

step 1

I need the math formula of how many Newtons will it take to get this trolley moving from a stationary position?

step 2

How many Newtons will it take to push this trolley over a bump on the floor? H

http://content.screencast.com/users/dchristensen777/folders/Default/media/60586f4a-cedd-4117-8698-04afc5060eaa/trolly.bmp [Broken]

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mfb
Mentor
That will depend on details of the bump structure, the size and typical mass and speed of the trolleys, the way they absorb shocks, and various other factors that are impossible to include in a pen&paper solution with reasonable effort (i.e. significantly cheaper than getting a new floor).
Experiments are probably easier - you can measure the time and effort needed to push a trolley over flat and bumpy ground, for example.

Suspension on the trolley is impossible. \$10 million worth of machinery is designed for this trolley. If suspension was added, it would not fit in the machines.

I understand that bump size, shape, and speed are a big factor. I'm not worried about that. I only want a rough idea. I'm doing this on my own, without pay. The managers don't know that I'm even doing this. Trials are not an option for political reasons. Half of the management don't even want to know how bad the floor is. 30% of the workers on the shop floor (including me) have health problems from pushing hundreds of these trolleys around all day. The intention of this spreadsheet is not to have an accurate rate of force required. It is to show that the bumps in the floor and the size of the wheels make a big difference. (and will give the managers that want the floor repaired some ammunition. At the moment, some of the managers are being an ostrich and are trying not to realize that the floor causes injury.

'It can't be done because .....' is an automatic response. Managers are not the only ones that do it. Some people that hang out on forums do it as well.

mfb
Mentor
You can try to use some geometry to estimate the angle the trolleys have to take to get up to a bump (or out of a hole) and then calculate the force needed for this angle - similar to an inclined plane, a standard textbook question. I doubt the result will help much, but that's probably the best you get without experiments or with a lot of effort.

If the trolleys carry sensitive or expensive material around, there could be another argument to fix the floor.