" Wouldn't want that thing dying when you need it most."

"Definitely a good idea for it being a massive, solid structure. One problem which could become an issue in time would be the fuel to run it. Unless you start pouring something else into the dozer, or have an abundance of diesel, trying to move that thing from your path would be dang near impossible.

But, if this is not an issue, that would be a great door, wide enough for vehicles to move in and out, sturdy and heavy enough to keep anything from pushing it, i don't care if Nemesis himself came walking up to it, that thing aint budging.

I actually have a very large open pit Copper Mine only about 10 miles give or take from my house, and from my BOB, it would only be about a 100 miles. They have some of these, as well as other very large machinery they use up there, so finding one would not be a problem for myself...."

"I like this idea, I'm just apprehensive about the Dozer not starting and the fuel requirements.

There's quite a few factors behind effective gate design. There's no doubt in my mind that I could build a gate that would be next to impossible to penetrate. The problem lies in opening and closing it easily and quickly.

Heavy vertically-hinged doors would have to be on well-balanced hinges. A tractor would have to be very well maintained, A portcullis system would have to be counterbalanced.

Personally I like the idea of a combo drawbridge/portcullis myself. But that would require immense fabrication time. The dozer has the perks of being much faster, and very intimidating."

"moat?"

"I designed the gate for the truck entrance of a structural steel company I worked for once. It was a two leaf swinging gate, hinged for a 225 degree arc. The hinges were nothing too carefully machined. Just thick plates with a bar stock hinge pin. There was no thought given to balance. It was largely a brute force kinda design. Fifteen years later they are still using it."

"Interesting.

What was it made of?
How big was it?
How heavy do you think it was?
How many people did it take to open it?"

"Some interesting ideas here but there may be a simpler solution. Think of a field gun or old fashioned cannon carriage. Your actual gate would be mounted on wheels like the cannon and the arms or 'trail' leads off behind.

Not only does the trail make the door easy to manage (whatever the weight is) but the more pressure applied to the outside of the door causes the trail dig itself in further. As it was designed to limit the recoil of a gun, no?

The heavier the door the longer the trail, I suppose you could mount a gun in it. . .
You might as well. . .
_"