On Thu, 26 Jan 2006 22:02:20 GMT, Nick Hull
wrote:

In article . com,
"TJH" wrote:

OK, perhaps this might sound strange, but I'd like to drop a car from a
crane.

I'm thinking about doing a project for a high school senior class to
show the violence of an auto crash (educational for prom week) at
roughly 30-45mph. In order to do this, I'd hoist an auto by a crane up
say 40 - 50 feet, and then drop it to the ground. But, to do this, I
need some type of quick release mechanism, because the crane owner
isn't going to risk damaging his equipment by free-falling the cable.

I've thought about using heavy duty strap webbing with a quick release
buckles, but I'm not sure if they would support the weight. The release
has another problem - how do I do it from the ground? Ideally, I would
have some sort of remote controlled release, but wireless? Wired?
Mechanical? Cheap and easy is the challenge as well.

If any have any suggestions, I'd love to hear them.

A standard bomb release would be perfect. IIRC, in WW2 the japs
strapped the bombs to the plane and used a cutter to release. A heavy
strap (seat belt?) and a paramedic seat belt cutter should work.

Dad made one by cutting a piece of 1" plate, drilling a hole for a big
anchor shackle, then cutting a notch which held another anchor
shackle. He welded a 3' stick of 1" round to the top to one side of
the hole. In practice, he hooked onto the captured shackle with the
winch truck, and hooked the slot shackle to a chain around a levee
roller, a concrete spool weighing about 2 tons. A rope was tied to
the 3' release handle. He winched to roller in the air, backed over a
junk car, and then pulled the rope from a safe distance. It dropped
the roller just fine, but the junker wrapped around the roller and we
had to cut it off. The objective had been to crush the old cars.

The release was crude, and probably unsafe, but there were no lawyers
around, and if there were we had access to a backhoe.

Pete Keillor