Trailer Leaf Spring Hanger Bolts

It's a matter of dividing the load over the number of members supporting it. That's not too much weight for a double axle trailer. Fully loaded, each tyre would carry 1,000#. Assume that each spring has four hanger bolts per side per axle with two load carrying points each, the shear force on the bolts would be 500# max.

I'd say 1/2" shoulder bolts would be overkill. Sorry, I don't do metrics.

I'd be more inclined to use 3/4" or 19mm bolts for the spring hangers but then that is a standard size in Oz for the Bushes used in our trailer springs regardless of the Gross Mass of the trailer.

The axle U bolts are 1/2" for the smaller 1/2tonne trailers but usually 5/8" for anything larger.

Kits are readily available in Oz over the counter or online, for making your own trailer be it single, tandem or triple axle type.

It all depends on whether it will be load sharing or not.

A load sharing tandem axle trailer will be nicer to tow and won't be as stressed in articulation over bumps as a non load sharing axle setup where there is the potential for the entire load to be carried by only one axle. If the axle/bearings/springs are not rated accordingly you will have trouble.

My 6 million dollar box trailer started as a run of the mill 6'x4' 3/4 ton trailer but upgrades during necessary rebuilds have "improved" this to 8'x4' with a 65mm axle running "Ford" 1.5tonne bearings (Gross Axle limit now 3 tonnes) with Landcruiser wheels and light truck tyres. I can happily load it to 2.5tonnes and not break it. Or lend it out and know that nobody else will break it either. One day I'll put brakes on it...

As you are just in the planning stage, plan on putting overide brakes on at least the front axle. Cable pull is ok, but hydraulic is better. Electric brakes are ok, as long as there is a dedicated tow vehicle set up for it, otherwise overide brakes are the way to go.

I know your in Kenya, what are the local traffic regulations regards trailers?

In Oz we have these government documents to deal with.

http://www.infrastructure.gov.au/roads/vehicle_regulation/bulletin/vsb1/index.aspx

Sounds like good advice to me.

When You purchase the leaf springs the appropriate bolts are included.

oilcan13

Hai id don't know the formula for calculating the capacity of the bolt, but try the M10 or M12 bolt with suitable for the leaf spring thickness. Check the standard tensile strength of the bolts i guess you can find the solution for your answer.

Thanks & Regards

Jayakrishnan

India

Throw that old slide rule in the back of the closet again. Just go look at someone other's mass produced trailer. If that manufacturer felt safe using what they did, It should be fine for you. Just go to a higher strength bolt than the factory used. most companies use softer bolts because they are cheaper to buy. For your small quantities, just buy the better hardware, in the same size. Good luck.