Thread: Building a steel folding ramp for 600kg capacity

Hi folks,

I posted previously with questions about building a steel loading ramp for ~350kg capacity. But plans have changed a fair bit - now I need 600kg capacity, and this piece of equipment has dreadful ground clearance - only 55mm at the lowest point. And while that low point is close to a set of wheels, it extends just far enough away from the wheels to make it a real pain... even on a 2.7m long straight ramp it will bottom out (according to a ground clearance jig I made up & tested last night). It's only going into the back of a Sprinter van, but the low clearance just kills any idea of a simple, straight forward ramp setup!

Using 2.3m folding alloy ramps with the little curve on the top section - no clearance problem at all. But setting up the folding ramps with tie down straps etc. multiple times per day would be a real pain. So I want to build a folding ramp similar to this that is easy to deploy and put back in the van:



I would just buy something like that if I could find it, this one is from Discount Ramps in the U.S. and it's $849 there, so I can only guess how much it would be here - cheaper (and more fun) to just make one myself.

I don't think I need the curve in the top section of the ramp, as long as it wasn't straight across the middle hinge I think that would work fine? Would you design the middle hinge so it doesn't open flat (to create the angle/curve)? Or just let it open flat and use the support legs to adjust the angle in the middle of the ramp?

I will probably add a spring assist lift mechanism out of the way on one side. But I can figure all that out. It's just the question of whether it's best to use an actual curved ramp section, or make it angled at the middle hinge? Also what type of hinge setup would you use? Weld-on pin hinge? Or just some metal tabs welded on, and bolted through? Or a series or tabs with solid bar running the whole width?

Cheers for any tips!

Hi Mugget,
What's the length of the item you're loading /unloading? The reason I ask is that sometimes a tailgate loader comes available, and it would be easier to operate, not require a wench and be resalable when you're done with it. I think I know where one is, it came off a Coaster bus, too expensive to repair the emergency hand pump. Can check for you if you're interested.
If that idea is out of the question, use 50 X 50 X 3 RHS, get it rolled into a curve that will allow your machine to be loaded. Cut in half for folding
and hinge it. Use expanded mesh will make it lighter, than using checker plate.
Kryn

Hi Kryn,

I think I jumped the gun a bit... or rather found an easier solution to my clearance problem!

It's a Walker ride on mower, the tractor wheelbase is 1020mm.

I was originally going to join together a few scaffold planks with about a 50-60mm gap in between, then I could just slide it under a false floor - easy slide in/slide out use. Thinking about building a folding ramp I realised it's quite involved...

Really the only issue will be the "tipover angle" when I get to the top of the ramp, coming into the vehicle. To solve that I thought about having a rubber wedge I can place on the ramp if needed, to give some extra clearance into the vehicle.



The low clearance is just one section near the front of the machine, a guard/frame support. It's only one piece near the middle, so I can have separate rubber sections only for the outside drive wheels, which will let the low piece pass through.

I think this will be much better, I could also have some higher rubber sections with me if I'm unloading on uneven ground with a larger ramp angle.

Thanks for the idea/heads up on the tailgate loader. I have thought about that before but I think it would be a bit overkill for me, would probably end up being a bit of a nuisance as well.

Cheers - I'll see how this idea goes!

some questions / observations

how do you (or what do you) tie the mower down to once it's inside the van?
Can I caution against tying down to a false floor.

will the ramp be permanently attached to the floor of the van?

The curve at the top of the ramp is about stopping the mower bottoming out. There are formulas that allow you to calculate what curve you need for any combination of ground clearance and change in angle from the ramp to the floor of your van.

Hi Ian,

Yes good points. The false floor will just be my current floor panel (single piece composite fibreglass construction) that is raised using aluminium rectangular tube. The floor panel is currently bolted down through the factory tie down points, those same points will be used once the floor panel is raised. And there will be additional bolt points because I will install cargo track around the centre of the floor. The bolts will all pass through the aluminium tube subfloor supports so it should all be sweet!

Here's the rough idea for the full layout:



The yellow pieces are the subfloor supports. The layout has changed a fair bit, but it gives the idea of how the subfloor supports & ramps all work together.

For tying down the mower I'll make up some brackets that will attach to the cargo track, with hold down clamps to quickly secure the mower. At least that's the plan for the back of the mower, so when I reverse into the van I can just nudge right into the bracket and know I'm in the right spot. For the front end of the mower (closest to the rear doors) I might just use a ratchet strap and the factory tie down points.

To secure the ramp I've been thinking about having a hinged 200-300mm section that will remain in the vehicle in the subfloor cavity. The idea would be that it just stops the top end of the ramp from flipping up, moving sideways, etc. It could be pulled all the way out... if that is a problem I can always add a catch latch/stopper on the underside of the ramp to stop it pulling out of the van.

Formulas to calculate the required clearance angle - that would be handy! But not sure I would be able to figure it out, I'm no math wizz...
I'm pretty happy with the jig I made up, it's just some pieces of 90x35mm timber screwed together but it replicates the ground clearance of the mower. I cut another length of timber to 2.7m to test the straight ramp length and the clearance was only short by about 10mm. (Kind of guessing because of the square edge of the timber, whereas the round tyres would have more surface area. Not sure if that would mean it could clear okay? But I figured if I'm measuring it by millimetres I'd be better off making sure that there's no doubt about it.)



It's good to be able to explain it to clever people, might save me missing something. At the very least makes me check that I know what's going on myself. Haha

Cheers

If the jig works, stay with it. I suggest you aim to achieve a "fat" 10mm of clearance with your ramp design.

tie downs
personally I don't like the idea of extending the factory fitted tie down points up to the false floor as the extended tie downs are then subject to bending.

To decrease to top angle of your ramp design use a scissor or trolley jack to lift the middle folding point.
To facilitate this the upper half of the ramp would need to fit the wheel base of your machine on it, maybe shift the hinge point down further?

Yes definitely, this fix should give at least 10mm of fat clearance!

I agree about using longer bolts & raising the tie down points, the only alternative I can think of is to reduce the distance between the tie down point & load whenever possible, so there's less of a sideways pull. But I think it will be a bit of a compromise either way - cumbersome, nuisance folding ramp and sturdier tie downs. Or super-easy slide away ramp and long tie down bolts. At least the bolts will be supported along their length, so it's not like a load at the top of the bolt will bend it at the base.

All good Harry - I've got a fix in mind, I will have enough clearance without needing a folding ramp.

personally I'd go for the cumbersome ramp.

Where I'm concerned is I think your tie down points are designed for near vertical or near horizontal loading. In a crash, the hold downs are supposed to restrain the load so that it doesn't slide forward and pin you against the inside front of the van.
The risk I see with the long bolts you propose is that in a crash, the bolts will bend enough to tear out of their mountings