I don't understand how suspensions work.

[Leatherhead]

I have compleated all of the maps, but I still don't understand how to use these, I always end up using some other material. Does anyone know how to use these effectively?

[Katmai]

(Edit: I'm stupid)

Eh, sure. But not knowing how you use them now, it's hard to say what you're doing wrong. They just either pull or push (clicking changes it) whatever they're connected to. You'll need a split joint (right click a joint) unless you're only moving the end of a ramp or so. The shorter the suspension is, the less it pulls/pushes (which makes fine-tuning a bit difficult).

That's it... I guess. It allows you to easily create a drawbridge like this, where the entire left side gets pulled up: http://imgur.com/jbRVheQ

Or even something that works like a lift. http://imgur.com/fytIrhs

[Leatherhead]

Those are Hydaulics. Suspensions are the really big cables strung between two towers that hold up other cables, like on the Golden Gate Bridge (or any other Suspension Bridge)

[Katmai]

Oh damn. Sorry, my bad.

Not a fan of suspension myself, seeing other solutions are currently just as, if not easier. But I do think you should stick with the triangle support for the roads and attach the cables to those, so it doesn't flop around. Not sure what else is there to them...

[Christian_Akacro]

Suspensions work by putting the load on the structures the suspension droops from. So in this image[i.ytimg.com] you can see that the only connections for the majority of the bridge are to the suspension via cables. This distributes most of the load of the bridge to the top of the two central towers.

Hope that helps, let us know if you have any more questions!

[Leatherhead]

Thanks! That does help quite a bit. I thought you had to use all of the connection points.

[OttosTheName]

Btw there's no point in using the Suspensions. They never have the same amount of yellow nodes as the bridge below it (at least not when they're at an angle) and the fact that they make an arch cost you stability.
You're much better off using cables and manually stringing them which ever way you prefer.
Like this kind of bridge for example[www.harzone.com.cn]

Suspension are just here for the looks, but are the priciest and least efficient way to build a bridge.
Making your own cable suspended bridge is also usually not the best option, it's way too expensive and weak compared to Truss bridges (lots of triangles)