Spring calculation?

[robwizard]

I have a cabinet which I want to add some suspension to and so I bought some gate castors rated to 57kg each, one on each corner to handle a load of about 100-120kg. Turns out they just bottom out completely with nothing in it So I need to buy some stiffer springs! Does anyone know a means of figuring out what springs I would need using the total weight and the size of the brackets/travel of the shaft?

I can attach photos if they will help to explain the issue

Cheers

 

[Kent]

I have a cabinet which I want to add some suspension to and so I bought some gate castors rated to 57kg each, one on each corner to handle a load of about 100-120kg. Turns out they just bottom out completely with nothing in it So I need to buy some stiffer springs! Does anyone know a means of figuring out what springs I would need using the total weight and the size of the brackets/travel of the shaft?

I can attach photos if they will help to explain the issue

Cheers

Read it three times still clueless

 

[scottmk1]

A quick google gives this and loads more https://www.acxesspring.com/spring-force-constant-calculator.html

 

[robwizard]

Read it three times still clueless

Me too!

A quick google gives this and loads more https://www.acxesspring.com/spring-force-constant-calculator.html

I'll give that a go cheers

 

[zzr1200]

I can attach photos if they will help to explain the issue

Cheers

Sounds like a good idea as I haven't got clue what your on about apart from a box/cabinet and some suspension/wheels..............

 

[bigegg]

he bought 4 of these:


to use as wheels on a cupboard.

he needs stiffer springs on them

how can he work out was sized springs he needs for a cupboard full of stuff.


ps, id be looking at trampoline springs, btw

 

[Luke]

You need to select springs with the correct rate. Hooke's Law states that F = kx, so for a given spring (with rate k), so much force (F) will change the length by x.

Your load is 120 kg, assuming that the majority of the load will be taken by 3 of the 4 wheels, the worst case distributed load is 40 kg. There are 9.81 N to a kg, so 392.4 N loading per spring.

If you'd like the springs to settle by 10 mm, you need a spring rate of 39.2 N/mm.

This spring has a rate of 37.41 N/mm, and a free length of 50.8 mm, so it'd end up with about 10.5 mm compression, and about 40 mm compressed length, which is a bit close to the min. compressed length of 37.2 mm, but you get the idea.

In reality, the 4th wheel will take some of the load, so it might be about right.

http://www.entexstocksprings.co.uk/index.php?route=product/product&product_id=1711

How are you going to stop the cabinet tipping over or leaning?

Luke

Edit - This could be a better fit - http://www.entexstocksprings.co.uk/index.php?route=product/product&product_id=1716

 

[robwizard]

@Luke That is perfect thanks! The cabinet lives inside a docking station with foam padding allowing it move in every direction a bit. It's also tethered to this docking station with wire rope to stop it tipping over or escaping at speed

Cheers

 

[Maker]

ps, id be looking at trampoline springs, btw

Those wheels use compression springs though, they'd need modifying to use trampoline (Extension) springs.

 

[bigegg]

true.

the ones i have were removed from a second hand trampoline, and have been over stretched, so have some compressive strength.

cut em to length, and theyd give 15-20mm of "give"