[oldopelguy]

Not that it really matters, but.....

Several of the local car dealerships use the type of ramp you are describing to highlight certain cars out in front. The same ramp is used for several different cars, trucks, and minivans, so there must be some sort of trick to it that makes them work no matter where the center of gravity is.

I was planning on taking a picture, but I haven't gotten out of the house much the last few days. (It is really cold here) The ramps are constructed, if you will, in the shape of the state of Nevada. Imagine the Utah side about 18 feet long and the northern half of the California side about 10 feet. Seperate those 2 parallel sides by about 4 feet, add a top and the remaining side and you're in there.

I whipped up a quick drawing to hopefully illustrate the dimension I would think is actually the most important:

 

[oldopelguy]

continuing:

The green line above represents where the car will be before any of the weight of the car passes the pivit point. As long as this part of the ramp is longer than the wheelbase of the car, then all of the weight of the car will be on the ramp before it can possibly move.

Then, after the ramp has pivited down, as long as the 2 parallel parts of the ramp are long enough to get the center of mass forward of the pivit point the ramp will be stabile in the down position. In the case of an Opel that would need to be at least 7 feet or so, but even a full sized pickup wouldn't need much more than 8 or 9, so fail conservative with 10 and your can work on your truck or car too.

You could also design the ramp with the short parallel leg intentionally short, so the car can't pivit the ramp. Add in even a $29 boat winch to PULL the front of the ramp down, and a couple of support legs in the rear to hold it after it is down, and you won't have to take any roller coaster rides in the car. The whole works would be shifted from outside the car, and certainly more easily than with any jack. You could then keep the angle of the ramp very low and use the winch to pull cars up onto the ramp as well.

 

[oldopelguy]

With the shorter leg

This shape has a winch for pulling the car onboard, then pulling the nose down to raise the whole car. With all manual controls it would work nice and slow (slower is safer) and still get the job done with minimal effort and time. Lifting the car off the engine and trans would be as easy as slowly releasing a hand winch.

You could even use it just as a big ramp for things like oil changes or the like where the whole works would be OK at an angle for a while. It would make detailing the undercarrage neat on, say, an old Olympia you were getting ready to tak to a car show.

By the way, anyone building a new garage?