Maximizing Weight Capacity for Casters on Carpeted Surfaces

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In summary, the table has a weight capacity of 500 pounds, but six caster wheels will double the load.
  • #1
Quietrabbit
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TL;DR Summary
I have a table and I am planning to put wheels on the four legs. How do I calculate the amount of weight the casters I buy need to hold, given the load
Currently I have 6 casters with a 90lb capacity, but I need this “table” (closest description to the shape) to hold over 500lbs. If I double up the wheels on the “legs” will that increase the weight capacity?
 
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  • #2
Can you post a sketch of the table? (Use the "Attach files" link below the Edit window)

What is the 500 pound load? What are the consequences if the table fails and the load falls?
 
  • #3
Remember, three points determine the "plane" of the table.
 
  • #4
The load is about 3 people (it's the frame for a prop), if it fails we fall :-)
I suppose I am assuming that 6x6s are sufficient to hold us up?
There is also a plywood top I didn't bother CADing.
 

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  • #5
Quietrabbit said:
The load is about 3 people (it's the frame for a prop), if it fails we fall :-)
Hmm, that's not good...

Does this get wheeled around as part of the scenes in the play, or only to move it between scenes? Is it moved with people on it?
 
  • #6
berkeman said:
Hmm, that's not good...

Does this get wheeled around as part of the scenes in the play, or only to move it between scenes? Is it moved with people on it?
Ideally it would be moved with people standing on it, during the scene. We're not too concerned with how we'll push it since worse case someone gets off.
 
  • #7
Quietrabbit said:
Currently I have 6 casters with a 90lb capacity, but I need this “table” (closest description to the shape) to hold over 500lbs. If I double up the wheels on the “legs” will that increase the weight capacity?
How do you plan on installing six caster wheels on four legs?

How flat and hard and free of steps and gaps the rolling surface is?
Small wheels easily catch on those surface irregularities.

Jumping backwards from 30 inches high is not so easy: tipping over toward the back of the bodies is the worst situation, as someone’s head may hit the floor.

Is it feasible to spread the location of the casters toward a square footprint?
 
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  • #8
Quietrabbit said:
The load is about 3 people (it's the frame for a prop), if it fails we fall :-)
How do you know that the three people will not all stand in the same corner, above the same leg?

Maybe you need to look at industrial strength casters that will be capable of supporting 500 lbs each.
https://www.ebay.com.au/itm/175035922479
 
  • #9
The surface is likely carpet and has no steps. The whole "table" is only 5'x2' so it's unlikely to be too unbalanced because of space constraints of where people can stand, but I see your point. People would likely sit and slide off, so I was hoping the weight of the wood would counteract most of that imbalance, especially if I get casters with brakes.
I didn't really think through how I would fit six casters, but they were small so I kinda figured I could fit 2 side by side on two of the 6x6 posts.
The posts would ideally stay where the are now, but I could add a horizontal brace at floor level in the short direction if you think that would help.

Is the suggestion that I need 500lb each?
 
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  • #10
Quietrabbit said:
Is the suggestion that I need 500lb each?
That is the sort of reality I would expect. When you push high up on a structure, that is travelling over, say a carpet that offers resistance to wheel movement, the supported weight is transferred to the front wheels.

Casters for heavier loads also have a greater diameter and floor contact patch, that will roll better over carpet. 4x industrial casters for $50 is a simple solution.
 
  • #11
Quietrabbit said:
Is the suggestion that I need 500lb each?
It is called a safety factor. Especially when human safety is involved, the factor should be generous. Three times the maximum load expected would be reasonable.

Three 200 pound people, plus 200 pounds for the wooden table, gives 800 pounds total. Factor of three for safety gives 2400 pounds, or 600 pounds per leg.
 
  • #12
Quietrabbit said:
The surface is likely carpet and has no steps. The whole "table" is only 5'x2' so it's unlikely to be too unbalanced because of space constraints of where people can stand
The people better not be standing when you try to push that table across carpet! Just trying to start that thing moving with little castors on it will cause a big jerking motion which would easily topple them off. Even when sitting, it will be an uncomfortable ride. At least when (not if) they fall off, it will be onto a carpeted surface and not concrete...
 

What is the formula for calculating force on casters?

The formula for calculating force on casters is force (F) = mass (m) x acceleration (a).

What units are used for force and mass in the calculation?

The units used for force are Newtons (N) and the units used for mass are kilograms (kg).

How do I determine the acceleration of an object?

The acceleration of an object can be determined by dividing the change in velocity by the change in time. This can be calculated using the formula a = (vf - vi)/t, where vf is the final velocity, vi is the initial velocity, and t is the time.

What factors can affect the force on casters?

The force on casters can be affected by the weight of the object being moved, the type and condition of the casters, the surface on which the casters are rolling, and any additional forces acting on the object (such as friction or air resistance).

How can I reduce the force on casters?

To reduce the force on casters, you can decrease the weight of the object, use larger or more durable casters, choose a smoother surface for the casters to roll on, and minimize any additional forces acting on the object.

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