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# Parking Swivel

A fifth wheel and a differential power system for very tight turns
 (+12, -1) [vote for, against]

My husband collects cars.  He is fanatical about not starting them unless they are going to be driven.  “Condensation collects in and corrodes the exhaust system unless they are brought up to full temperature,” he says.  So, he often uses a hydraulic floor jack under the rear of the car to move the cars around in the garage.  It’s amazing how adept he has gotten at gliding the cars around--getting them in and out of tight spots--just using that floor jack.  Watching him do this tonight got me to thinking . . . .

How nice it would be if my (non-collectable) car was equipped with a small, heavy-duty 5th wheel that descended and picked up the back end of the car just enough to allow the rear of the car to be moved laterally on the 5th wheel.  The small, hard-rubber adorned, wheel would caster and the transaxle would supply directional impetus through the front wheels by channeling power precisely, differentially, to each wheel based on input from the steering wheel.  Turn the steering wheel slightly left and the back of the car swings to the right, and vice versa.  The further the steering wheel is turned, the tighter the arc, until some limit, perhaps the caster limit of the 5th wheel, is reached.  One wheel would have to roll forwards and the other backwards to do very tight turns and slightly wider sweeps would only need one wheel to roll while the other is stoutly held stationary.  The throttle would be managed by the power system (as it is when traction control engages), so that the rate of turn is safe and slow.  With this arrangement, I could navigate in and out of very tight spots by pirouetting on the front wheels to orient the car and then retracting the 5th wheel and moving into the spot normally.  This system would only work on front-wheel drive cars, of course.

There are a few patents covering systems similar to this but none of them use differential power to the drive wheels to effect the lateral motion (as far as my searches revealed).  No mercy votes, please.  If you think this is baked . . . 'bone it.

 — bristolz, Mar 28 2002

Crabbing wheel idea http://www.halfbake...m/idea/rear_20steer
Main wheels crab but not nearly as tightly as a fifth wheel, or rear-steering vehicle. [bristolz, Mar 28 2002]

Dymaxion three-wheel car http://www.pbs.org/wnet/bucky/car.html
R. Buckminster Fuller's car design featuring rear wheel steering. This car could turn tightly like I want but at the cost of horrendous instability at road speeds. [bristolz, Mar 28 2002]

Vehicle mounted parking device http://www.delphion...ils?pn10=US04516653
A patent that, for the life of me, I can't figure out if it's using the same idea or not for transmitting the power to the ground to effect a swiveling motion. [bristolz, Mar 28 2002, last modified Apr 12 2002]

Floor jacks http://www.hyjacks.com/H22.HTM
In case you don't know what a floor jack is. [bristolz, Mar 29 2002]

AutoJack http://www.halfbakery.com/idea/AutoJack
[StarChaser, Mar 29 2002]

Does he have any extra cars laying around?
Is this a contest where the first annotation wins it?
 — thumbwax, Mar 28 2002

Impressive use of “Smart Quotes”, bris.
Oh yes - nice idea too. Croissant. Can the 5th wheel be used for jacking the car up to change tyres too?
 — hippo, Mar 28 2002

Currently, the only dance available to cars is the Pogo. Bristolz' device would open up a whole new world of dance moves. "The Bump," for instance.
 — beauxeault, Mar 28 2002

 I need this badly so you have my +. It takes me about 20 minutes to parallel park.

The image this brings to mind is of those battery-operated noisy toy cars from childhood, which had the center wheel poking down. You know, the ones with the spinning motion, so the car moves in random directions and can back away from an obstacle.
 — waugsqueke, Mar 28 2002

 This was baked in the 30's. Saw a movie of a model T with an extra wheel that worked exactly like this. Thought it was a good idea then, and still is now...

Heh! Halfbaked, too. I went looking for it, and found the same thing on the Halfbakery, as the first link.
 — StarChaser, Mar 29 2002

Sorry, I guess I did a poor job writing the description as my intent is that the idea is to do with the way the car is impelled to move laterally through differential power controlled through the steering wheel rather than the car-borne jack (the jack part is quite baked).
 — bristolz, Mar 29 2002

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