Wednesday, 25 July 2012

Ramping My Style

This may well be the final post of the trailer build, I finally got the MIG welder set up for ally a couple of weekends ago and had a stab at making the ramps.

The previous ramp design was simply to bolt a length of 40x40 angle steel down each side of the runners to provide some stiffness and weld in some cross bars to hold them together, if you have a look in the back ground of the photo's in previous posts you can see them kicking about. Unfortunately they this was nowhere near strong enough so a new solution had to be sought.

We decided that welding in two lengths of 50x50 aluminium channel using the lower surface of the ramp to complete a box section  was the way forward as not only would this give us twice as many vertical webs but they would be over 10mm deeper, the material was a full mm thicker and they would be forming not one but two hallowed box sections that were welded (not bolted) into place, something we were entirely lacking with the previous design.

I had one roll of wire and two small cylinders of Argon so after a mere six inches of practise welds on some off-cuts to get a feel for the right setting and technique it was time to go for it. Ill let you make your own minds up.

I must say I'm fairly happy with the results, for a first attempt they came out pretty good. aluminium behaves totally differently to steel, it's much softer so you use loads of wire and need a much higher wire-speed, it expands when heated a lot more than steel so you need to stay further away from the arc to prevent the wire getting stuck in the tip and the heat doesn't seem to sink into it in quite the same way. I think with more time to find the perfect setting and perfect my technique I could get some tidy looking welds. As it is, some were really good and some not so good and I don't have the experience yet to know why that is, even with the really good ones I was getting lots of spatter and not quite the same level of penetration I can get with steel but I think to do really good job of Ally you need a TIG welder and that's way out of my price range (yes I'm blaming my tools).

We also needed to devise a way of storing the ramps on the chassis when they're not in use. The runners and ramps are 400mm wide and quite by chance the space between them is just over 800mm so it was immediately obvious where they would be going, it was merely a question of thinking of a simple method of holding them to the chassis that allowed easy access with a car on board and didn't have them rattling around.

We decided on a nice, simple under/over lever set-up and over-centre clamps. Basically the ramps go under a bar in the middle of the chassis:

Over another bar that's slightly less than the the depth of the ramp lower than the first bar toward the rear of the trailer:

So a heavy duty stainless over-centre clamp can pull it tight against the bottom/top of each bar to hold it firmly in place:

The middle bar is a little too high which is why they don't pull neatly down to meet the chassis, this is because it was welded in before we knew the ramps themselves were going to need a rethink, but it's a simple enough job to chop it out and weld it back in a little lower. But for now they look great, can be easily loaded and unloaded, with or without a car on board and its all padded out with rubber pads so they don't rattle in the slightest, that's all the boxes ticked.

As you can see the trailer seems to be in a new location, that's because its at my folk's pace in north Wales but I think I'll keep that for the next post.