Team-BHP - Fiat Premier Padmini - Shorter turning radius in reverse???
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-   -   Fiat Premier Padmini - Shorter turning radius in reverse??? (https://www.team-bhp.com/forum/technical-stuff/62105-fiat-premier-padmini-shorter-turning-radius-reverse.html)

An uncle recently told me that the Fiat PP had a shorter turning circle in reverse.

I was a bit confused as to how this could be possible.

Can anyone explain as to what causes this, if at all its true.

Shan2nu

Check out in this thread.

http://www.team-bhp.com/forum/post-1...on-thread.html

I think your uncle was pulling a fast one on you, Shantanu :D

Quote:

I think your uncle was pulling a fast one on you, Shantanu
He is not the kind who jokes about such things. But somehow, he has been made to believe that this is possible.

Technically, it makes no sense but i thought id get some inputs from the various FPP owners/enthusiasts on the forum.

Shan2nu

I have no clue about the turning radius issue, but i can tell you one thing, there is on fiat premier padmini, its either a fiat 1100 delite or a premier padmini. :)

He prob meant PP coz he said the Bbay taxi walas also use this trick.

Shan2nu

I think the Premier Padmini had a front wheel alignment which was 'different': when the wheel is fully turned to the right or left, the wheel will show negative camber.

This kind of wheel alignment probably has a role in making the steering easier to turn in reverse than when moving forward (hence creating the perception that there is a shorter turning radius in reverse). This is just some loud-thinking on my part. I could be way off the mark here, though.

may be one of the reasons why heavy vehicles like the large cranes use the rear wheels to steer. i saw one series on the Discovery channel that the large fire fighting / ladder trucks in the US have a separate portion at the back to steer in narrow lanes.

i think it is same in case of all cars - why do reverse while parallel parking between two cars?

Edit:

Quote:

A tiller truck, also known as a tractor drawn aerial or a hook-and-ladder truck, is a specialised turntable ladder mounted on a semi-trailer truck. It has separate steering wheels for front and rear wheels. This truck is often used in areas with narrow streets that prevent longer single-vehicle trucks from entering. Some cities, including Los Angeles, San Francisco, Dallas, Baltimore, Seattle, and Philadelphia rely heavily on them. The hook-and-ladder concept started when larger skyscrapers and more city streets became a problem for fire departments. Larger ladders were needed to get to upper stories of buildings, and the only way to move them was in this format.
Fiat Premier Padmini - Shorter turning radius in reverse???-800pxlafd_ladder_truck.jpg

No, he wasn't talking about reverse parking. That we all know that its easier to allign the car when parking in reverse.

He meant the turning radius, which is what you get when you keep going round n round with full steering lock. This i find hard to believe.

Shan2nu

i gotto check it out :) - i will let you know later by tomorrow.

I do not know about the total turning radius but, the PP seemed to turn sharper when turned in reverse.

Cheers

i believe that it is the same in case of all cars.

@ shantanu - have you tried it with your OHC?

Quote:

i believe that it is the same in case of all cars.

@ shantanu - have you tried it with your OHC?
No, but i guess if it works for one car it should work for all cars with 2 wheel drive and front wheel steering.

But i dont see this happening unless there is some wheelspin/sliding involved.

If a car needs a certain radius to turn in 1st, it should do the same in reverse as the turning circle is decided by the circumference created by the outermost wheel.

Shan2nu

Its the same with all cars and thats the reason why PARALLEL PARKING TECHNIQUE is the most preferred methods......
When the vehicle is moving FORWARDS and is steered to one side, the rear wheels do not follow the path of the front wheels but travels at a DISPLACEMENT DISTANCE with respect to the FRONT WHEELS (i.e. a Shorter Path/ Shorter travel distance).
Hence when you drive the vehicle in reverse and TURN, the rear inner wheel act as PIVOT POINT (or like a HINGE POINT). So practically your rear inner wheel with respect to the turn stand almost at the same position (compared to other wheels movement) and the vehicle rotates about that wheel.

A very simple and good example is to consider a SMALL BOAT WITH A TAIL RADDER/TAIL MOTOR to steer it which makes very sharp turns

Quote:

Its the same with all cars and thats the reason why PARALLEL PARKING TECHNIQUE is the most preferred methods......
When the vehicle is moving FORWARDS and is steered to one side, the rear wheels do not follow the path of the front wheels but travels at a DISPLACEMENT DISTANCE with respect to the FRONT WHEELS (i.e. a Shorter Path/ Shorter travel distance).
Hence when you drive the vehicle in reverse and TURN, the rear inner wheel act as PIVOT POINT (or like a HINGE POINT). So practically your rear inner wheel with respect to the turn stand almost at the same position (compared to other wheels movement) and the vehicle rotates about that wheel.

A very simple and good example is to consider a SMALL BOAT WITH A TAIL RADDER/TAIL MOTOR to steer it which makes very sharp turns
W.R.T to parking in tight places, this is a well know fact, since reverse parking gives you better steering control over the side of the car that needs to be alligned last.

But when it comes to turning radius/circle, i think the car should need the same amount of space whether its in forward or backward motion.

If any off you have those 1:18 scale models (I can already see Dippy smiling from ear to ear, lol), you could turn the steering to full lock and just see how it behaves when moved forward and backward.

Atleast from what iv noticed, the turning circle is identical.

Shan2nu


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