The tractor retractor can be a built in or bolt on addition to rough terrain vehicles. I imagine it easier to engineer for four wheel vehicles, but i'll try to explain it for a single rail three wheeler (4 wheelers could have double rails).
A 3 wheel tractor hits a soft patch of earth, pure swamp you might say. One tire sinks down deep into the quagmire. Up to the frame! Go ask farmer Ron if his International can pull you out.
The tractor retractor is a steel beam sitting on the underbelly of the tractor. It is attached to hydraulic pistons and has the power to lift the tractor out of the sunken mess. Now, you as the driver will have to go get some logs or such to throw across the tire digit, but no need to plead to farmer Ron and his international again.
Note: this system probably works better for 4 wheel heavy lifters who need to operate in soft soils as two beams could lift the vehicle.-- Zimmy, Jul 01 2011 High Lift Jack http://www.hi-lift.com/Widely used for the purpose described. [Twizz, Jul 01 2011] I can't figure out how to edit on this phone right now. I wanted to change the last line to indicate the stability advantage of dual retractor rails.
Oooh, yeah! You can't take the country out of the boy, can you?-- Zimmy, Jul 01 2011 I envisage the steel beams also sinking into the mire.-- pocmloc, Jul 01 2011 beam will need a large plate at bottom.-- VJW, Jul 01 2011 The high lift jack requires no power other than the operator, can be transferred from one vehicle to another, requires no installation, can be used as a winch and as a jack at any angle (such as pushing the vehicle away from the rock it's jammed against).
I've done this a lot. With a high lift jack, you lift the vehicle's wheels out of their holes, then push it sideways to topple it off the jack and onto the ground beside the holes.
Redundant.-- Twizz, Jul 01 2011 I too have felt your pain, [Twizz]. It is the price of love for your 4x4.
The rails would not have to be more than 4" wide on a large vehicle, provided they run most of the length between the axles (I assume they were not intended to run the full length of the vehicle, as this would interfere with the suspension). It's a matter of surface area, guys, not shape.
What I'm most concened about is safety. Improper use of this on uneven ground or a slope could be disastrous, as could accidental or malfunction deployment on solid ground. Plus, the system will take a lot of wear and tear, because you know the operator is just going to use it to lift the machine when he needs to instead of going back to the garage and finding a jack.
[+]-- Alterother, Jul 01 2011 This would be enormously heavy and contribute to getting stuck more often, I'm afraid.-- RayfordSteele, Jul 01 2011 Yeah, but the sound it made when accidentally deployed at highway speeds would be memorable.-- normzone, Jul 01 2011 I thought about the weight, too, but it wouldn't actually add much to the weight of a farm tractor, which is tremendously heavy to begin with, what with the cast-iron axles and all. Some hydraulic pistons, a couple of flanged steel rails, and associated mechanical gubbinz: I figure 600-800 lbs, tops, and that's for a large-ish tractor.-- Alterother, Jul 01 2011 random, halfbakery