how does TX4 taxi achieve tight turning circle?

[b***@topmail.co.nz]

London taxis are supposed to have a 25-foot turning circle.
Other RWD cars with same wheelbase would have turning circle over 30 feet.
I am told the Chinese-made TX4 does achieve this tight circle as it uses
a different steering rack. I had assumed that the front wheels were
turned more than other cars, and it has narrow tyres that would allow this.
I looked at videos of the taxi and front wheels only seem to twist about 45
degrees on full lock. Fork lift trucks twist wheels more than that.
I have also seen an old LWB Bentley whose front wheels twisted more.
Is the front end setup with some unusual combination of camber and scrub
radius or whatever that permits tight turns? I would presume it is
something others avoid as it increases tyre wear or degrades handling.

[Chris Whelan]

On Tue, 08 Apr 2014 06:24:40 -0700, bruce56 wrote:

> London taxis are supposed to have a 25-foot turning circle.

Yep. The reason why? Scroll down to vehicle design:

http://en.wikipedia.org/wiki/Hackney_carriage#Vehicle_design

> Other RWD cars with same wheelbase would have turning circle over 30
> feet. I am told the Chinese-made TX4 does achieve this tight circle as
> it uses a different steering rack. I had assumed that the front wheels
> were turned more than other cars, and it has narrow tyres that would
> allow this.
> I looked at videos of the taxi and front wheels only seem to twist about
> 45 degrees on full lock. Fork lift trucks twist wheels more than that.
> I have also seen an old LWB Bentley whose front wheels twisted more.
> Is the front end setup with some unusual combination of camber and scrub
> radius or whatever that permits tight turns? I would presume it is
> something others avoid as it increases tyre wear or degrades handling.

A friend once owned an ex-London taxi as a cheap runabout. They don't
handle, and they do wear their front tyres fast! At the age his was, they
were not allowed to have lockable rear doors. His solution was to tie
them together inside...

There is nothing special about the steering arrangement, apart from being
very old-fashioned on even the latest models.

Chris

--
Remove prejudice to reply.

[Dave Plowman (News)]

In article <li120g$7eg$***@dont-email.me>,
Chris Whelan <***@prejudicentlworld.com> wrote:
> A friend once owned an ex-London taxi as a cheap runabout. They don't
> handle, and they do wear their front tyres fast!

It was probably on crossplies which accounts for both...

They had 16" wheels in the days when 15" was about the largest common size
so radials for them were rare and expensive. They also made the steering
even heavier - before power steering arrived.

--
*A closed mouth gathers no feet.

Dave Plowman ***@davenoise.co.uk London SW
To e-mail, change noise into sound.

[Mrcheerful]

On 08/04/2014 16:16, Dave Plowman (News) wrote:
> In article <li120g$7eg$***@dont-email.me>,
> Chris Whelan <***@prejudicentlworld.com> wrote:
>> A friend once owned an ex-London taxi as a cheap runabout. They don't
>> handle, and they do wear their front tyres fast!
>
> It was probably on crossplies which accounts for both...
>
> They had 16" wheels in the days when 15" was about the largest common size
> so radials for them were rare and expensive. They also made the steering
> even heavier - before power steering arrived.
>

yet the new nissan taxi will have 14 inch wheels, bizarre.

[Dave Plowman (News)]

In article <hKU0v.115855$***@fx11.am4>,
Mrcheerful <***@yahoo.co.uk> wrote:
> On 08/04/2014 16:16, Dave Plowman (News) wrote:
> > In article <li120g$7eg$***@dont-email.me>,
> > Chris Whelan <***@prejudicentlworld.com> wrote:
> >> A friend once owned an ex-London taxi as a cheap runabout. They don't
> >> handle, and they do wear their front tyres fast!
> >
> > It was probably on crossplies which accounts for both...
> >
> > They had 16" wheels in the days when 15" was about the largest common
> > size so radials for them were rare and expensive. They also made the
> > steering even heavier - before power steering arrived.
> >

> yet the new nissan taxi will have 14 inch wheels, bizarre.

I'd guess they've relaxed the regs? (At one time all chassis nuts had to
be wired - and so on)

--
*When did my wild oats turn to prunes and all bran?

Dave Plowman ***@davenoise.co.uk London SW
To e-mail, change noise into sound.

[Adrian]

On Tue, 08 Apr 2014 18:06:13 +0100, Dave Plowman (News) wrote:

>> yet the new nissan taxi will have 14 inch wheels, bizarre.

> I'd guess they've relaxed the regs? (At one time all chassis nuts had to
> be wired - and so on)

A quick google reckons not - the NV200 van's had the suspension raised to
meet the ground clearance requirement.

What's most interesting about it, though, is that it meets the turning
circle requirement - despite being FWD, and without having to resort to
the rear-steer of the Merc Vito taxi (RWD). Any bets on how long the CV
joints are going to last?

[Dave Plowman (News)]

In article <li1bk0$42d$***@speranza.aioe.org>,
Adrian <***@gmail.com> wrote:
> What's most interesting about it, though, is that it meets the turning
> circle requirement - despite being FWD, and without having to resort to
> the rear-steer of the Merc Vito taxi (RWD). Any bets on how long the CV
> joints are going to last?

The Triumph 1300/1500 FWD had an excellent turning circle. They achieved
this by angling the driveshafts. Not quite as good as the Herald, but
close.

--
*When chemists die, they barium.*

Dave Plowman ***@davenoise.co.uk London SW
To e-mail, change noise into sound.

[b***@topmail.co.nz]

On Wednesday, April 9, 2014 1:28:32 AM UTC+8, Adrian wrote:
>
> A quick google reckons not - the NV200 van's had the suspension raised to
>
> meet the ground clearance requirement.
>
>
>
> What's most interesting about it, though, is that it meets the turning
>
> circle requirement - despite being FWD, and without having to resort to
>
> the rear-steer of the Merc Vito taxi (RWD). Any bets on how long the CV
>
> joints are going to last?

The NV200 taxi has an extra universal joint to allow the increased angle.
So the drivetrain is Cardan plus Birfield plus odd number of uni joints.
Will no longer be constant velocity. I reckon it must wobble a bit going
around the Savoy.

[Duncan Wood]

On Wed, 09 Apr 2014 10:39:02 +0100, <***@topmail.co.nz> wrote:

> On Wednesday, April 9, 2014 1:28:32 AM UTC+8, Adrian wrote:
>>
>> A quick google reckons not - the NV200 van's had the suspension raised
>> to
>>
>> meet the ground clearance requirement.
>>
>>
>>
>> What's most interesting about it, though, is that it meets the turning
>>
>> circle requirement - despite being FWD, and without having to resort to
>>
>> the rear-steer of the Merc Vito taxi (RWD). Any bets on how long the CV
>>
>> joints are going to last?
>
> The NV200 taxi has an extra universal joint to allow the increased angle.
> So the drivetrain is Cardan plus Birfield plus odd number of uni joints.
> Will no longer be constant velocity. I reckon it must wobble a bit going
> around the Savoy.


Well a cardan joint plus an odd number of inversal joints is an even
number.

[b***@topmail.co.nz]

On Thursday, April 10, 2014 5:02:44 AM UTC+8, Duncan Wood wrote:
>
>
> Well a cardan joint plus an odd number of inversal joints is an even
>
> number.

I meant Cardan shaft (a joint at each end).

[b***@topmail.co.nz]

On Wednesday, April 9, 2014 1:28:32 AM UTC+8, Adrian wrote:
>
> What's most interesting about it, though, is that it meets the turning
>
> circle requirement - despite being FWD, and without having to resort to
>
> the rear-steer of the Merc Vito taxi (RWD). Any bets on how long the CV
>
> joints are going to last?

And as for the Merc London taxi, they used 4-wheel steering to achieve
the 25-foot turning circle. So it probably has good handling, but must
be fairly expensive.

[Adrian]

On Wed, 09 Apr 2014 02:43:29 -0700, bruce56 wrote:

> On Wednesday, April 9, 2014 1:28:32 AM UTC+8, Adrian wrote:
>> ... without having to resort to the rear-steer of the Merc Vito taxi

> And as for the Merc London taxi, they used 4-wheel steering

Gosh, did they?

[Chris Whelan]

On Tue, 08 Apr 2014 16:16:51 +0100, Dave Plowman (News) wrote:

[...]

> They had 16" wheels in the days when 15" was about the largest common
> size so radials for them were rare and expensive.

Yes, partly due to the somewhat bizarre requirement to have a minimum of
seven inches ground clearance.

Chris

--
Remove prejudice to reply.

[Mrcheerful]

On 08/04/2014 18:19, Chris Whelan wrote:
> On Tue, 08 Apr 2014 16:16:51 +0100, Dave Plowman (News) wrote:
>
> [...]
>
>> They had 16" wheels in the days when 15" was about the largest common
>> size so radials for them were rare and expensive.
>
> Yes, partly due to the somewhat bizarre requirement to have a minimum of
> seven inches ground clearance.
>
> Chris
>

ten according to the nv200 specs

[Chris Whelan]

On Tue, 08 Apr 2014 18:39:07 +0100, Mrcheerful wrote:

> On 08/04/2014 18:19, Chris Whelan wrote:
>> On Tue, 08 Apr 2014 16:16:51 +0100, Dave Plowman (News) wrote:
>>
>> [...]
>>
>>> They had 16" wheels in the days when 15" was about the largest common
>>> size so radials for them were rare and expensive.
>>
>> Yes, partly due to the somewhat bizarre requirement to have a minimum
>> of seven inches ground clearance.
>>
>> Chris
>>
>>
> ten according to the nv200 specs

Apparently only up until 1927 ;-)

http://en.wikipedia.org/wiki/Conditions_of_Fitness

Chris

--
Remove prejudice to reply.

[Peter Hill]

On 08/04/2014 14:24, ***@topmail.co.nz wrote:
> London taxis are supposed to have a 25-foot turning circle.
> Other RWD cars with same wheelbase would have turning circle over 30 feet.
> I am told the Chinese-made TX4 does achieve this tight circle as it uses
> a different steering rack. I had assumed that the front wheels were
> turned more than other cars, and it has narrow tyres that would allow this.
> I looked at videos of the taxi and front wheels only seem to twist about 45
> degrees on full lock. Fork lift trucks twist wheels more than that.
> I have also seen an old LWB Bentley whose front wheels twisted more.
> Is the front end setup with some unusual combination of camber and scrub
> radius or whatever that permits tight turns? I would presume it is
> something others avoid as it increases tyre wear or degrades handling.
>

It was required to have that turning circle so they don't have to do 3
point turns to collect a fare on the other side of the road. AND it's
wall to wall turning circle - that wall will be a wall of people on the
pavement.

While these days the local "taxis" bring the A511 in Burton on Trent to
a halt doing a 3 point turn. 20m away from a nice quiet side road where
they could that other "quiet road" driving test standard "reversing
round a corner".

http://www.autoindustryinsider.com/wp-content/uploads/2012/10/LTi-TX4-front-suspension-080906.jpg
http://www.baconsdozen.co.uk/taxi/susosf2.jpg
http://www.baconsdozen.co.uk/taxi/susosf3.jpg
1: Fabricated lower "A" arm with very curved front tension arm bolted to
front of the lower arm. Normally the tension rod would be straight - it
will tend to bend straight every time it brakes.
2: Lever arm steering with whacking long lever.
3: Lots of neg camber!
4: Upper A arm very high in a big wheel with a very small base at the
chassis end.

So the answer is by having utterly shit handling.

Kerb to kerb you can deduct about 1-2ft.

Triumph Spitfire had 24ft - kerb to kerb?
72 Datsun 1200 coupe 26 ft, 4 inches
Herald 27ft.

31.1ft (9.5m) does me and my 200SX just fine. Don't get many cars with
that sort of turning circle any more, most are around 36ft (11m). MX-5
is about the only one and that's an impractical 2 seater.

On this claimed "TOP 10" list only the Yaris has a decent turning circle
- which means it's easy to park, either in short spaces when parallel
parking or in car parks with narrow lanes between the rows. Yaris may be
as good as the old Mini for turning circle. Old Mini had mods very early
on as it was so crap when first produced they had to FIX it, while the
NEW Mini is hopeless.
http://www.cars.com/go/advice/Story.jsp?section=top&subject=more&story=top10urban

This list starts off well with Smart Four2 28.7ft and Fiat 500 30.6ft,
then they mess it up by claiming the 35.1ft Mini Copper as "good". Oops.
http://www.automobilemag.com/features/news/1107_best_cars_for_people_who_can_t_park/

Utterly clueless as what a "good" turning circle is or the value of it.
What do you expect?
http://www.forbes.com/2008/02/13/cars-city-driving-forbeslife-cx_jm_0213citycars.html

A bunch of barge owners prove to be yet more clueless idiots.
http://www.mbclub.co.uk/forums/general-discussion/134878-amazing-turning-circle.html
None are better than 35ft.
http://www.mybenz.org/zoopp/html/modules/newb/viewtopic.php?topic_id=8291&forum=1
While the Volvo 740 one mentions is a whole yard less at 32ft - it makes
all the difference between a kerb to kerb or a 3 pointer becoming a 5.
That C70 has to be wrong, how have they gone from fairly good to that
sad joke at 38.4ft? Lost all their design rules, values and integrity
under Ford ownership? Link below V70 seems to have a much bigger turning
circle for Auto 40ft compared to Manual 36.7ft. Is it restricted by
gearbox to wheel clearance? Both are barges.
https://www.media.volvocars.com/global/en-gb/models/v70/2013/specifications

And when it comes to skidding the RWD car with most opposite lock and a
back axle that doesn't throw a fit about it wins.

--
Peter Hill
replace nospam with domain host name to reply

[b***@topmail.co.nz]

On Wednesday, April 9, 2014 7:16:58 AM UTC+8, Peter Hill wrote:

>
> While the Volvo 740 one mentions is a whole yard less at 32ft - it makes
>
> all the difference between a kerb to kerb or a 3 pointer becoming a 5.
>
> That C70 has to be wrong, how have they gone from fairly good to that
>
> sad joke at 38.4ft? Lost all their design rules, values and integrity
>
> under Ford ownership? Link below V70 seems to have a much bigger turning
>
> circle for Auto 40ft compared to Manual 36.7ft. Is it restricted by
>
> gearbox to wheel clearance? Both are barges.
>
> https://www.media.volvocars.com/global/en-gb/models/v70/2013/specifications
>
>
Volvo 700 series was RWD. C70 is FWD.
Usually the difference in turning circle is less than 4.7 feet.

[The Revd]

On Tue, 8 Apr 2014 06:24:40 -0700 (PDT), ***@topmail.co.nz wrote:

>London taxis are supposed to have a 25-foot turning circle.
>Other RWD cars with same wheelbase would have turning circle over 30 feet.
>I am told the Chinese-made TX4 does achieve this tight circle as it uses
>a different steering rack. I had assumed that the front wheels were
>turned more than other cars, and it has narrow tyres that would allow this.
>I looked at videos of the taxi and front wheels only seem to twist about 45
>degrees on full lock. Fork lift trucks twist wheels more than that.
>I have also seen an old LWB Bentley whose front wheels twisted more.
>Is the front end setup with some unusual combination of camber and scrub
>radius or whatever that permits tight turns? I would presume it is
>something others avoid as it increases tyre wear or degrades handling.

In the 1960s, oil millionaire Nubar Gulbenkian drove about in a
custom-built gold and black taxi. He once exclaimed "It can turn on a
sixpence - whatever that is."

[The Peeler]

On Tue, 08 Apr 2014 16:35:34 -0700, The Rectum, the resident psychopath of
sci and scj and Usenet's famous sexual cripple, FAKING his time zone again,
farted:

>>Is the front end setup with some unusual combination of camber and scrub
>>radius or whatever that permits tight turns? I would presume it is
>>something others avoid as it increases tyre wear or degrades handling.
>
> In the 1960s, oil millionaire Nubar Gulbenkian drove about in a
> custom-built gold and black taxi. He once exclaimed "It can turn on a
> sixpence - whatever that is."

Even he would have considered you an asshole, The Rectum!

--
Retarded, anal, subnormal and extremely proud of it: our resident
psychopath, The Retard (aka "The Rectum").

[Mr Pounder]

<***@topmail.co.nz> wrote in message
news:7d2210de-742b-48cb-be4f-***@googlegroups.com...
> London taxis are supposed to have a 25-foot turning circle.
> Other RWD cars with same wheelbase would have turning circle over 30 feet.
> I am told the Chinese-made TX4 does achieve this tight circle as it uses
> a different steering rack. I had assumed that the front wheels were
> turned more than other cars, and it has narrow tyres that would allow
> this.
> I looked at videos of the taxi and front wheels only seem to twist about
> 45
> degrees on full lock. Fork lift trucks twist wheels more than that.
> I have also seen an old LWB Bentley whose front wheels twisted more.
> Is the front end setup with some unusual combination of camber and scrub
> radius or whatever that permits tight turns? I would presume it is
> something others avoid as it increases tyre wear or degrades handling.

Ever owned a Triumph Herald?

[b***@topmail.co.nz]

On Saturday, April 12, 2014 5:18:50 AM UTC+8, Mr Pounder wrote:
>
> Ever owned a Triumph Herald?

No. I have seen its turning circle quoted as 25' and also 26'4""
That requires a steering angle of 43 degrees. I think most cars
today stop at 38 degrees.
Anyway it is a 2-door car somewhat smaller than a taxi.

[Chris Whelan]

On Sun, 13 Apr 2014 01:25:33 -0700, bruce56 wrote:

> On Saturday, April 12, 2014 5:18:50 AM UTC+8, Mr Pounder wrote:
>>
>> Ever owned a Triumph Herald?
>
> No. I have seen its turning circle quoted as 25' and also 26'4""
> That requires a steering angle of 43 degrees. I think most cars today
> stop at 38 degrees.
> Anyway it is a 2-door car somewhat smaller than a taxi.

Oddly, there is a factor to consider with those two vehicles - the type
of steering. They both have 'old-fashioned' systems, using a steering box
and links. Using a rack and pinion box might make it more difficult to
achieve the articulation needed.

As an aside, the (non-commercial) vehicle with the worst turning circle I
have ever driven is a LR 110; it completely caught me out the first time
I drove one!

Chris

--
Remove prejudice to reply.

[Mrcheerful]

On 13/04/2014 09:52, Chris Whelan wrote:
> On Sun, 13 Apr 2014 01:25:33 -0700, bruce56 wrote:
>
>> On Saturday, April 12, 2014 5:18:50 AM UTC+8, Mr Pounder wrote:
>>>
>>> Ever owned a Triumph Herald?
>>
>> No. I have seen its turning circle quoted as 25' and also 26'4""
>> That requires a steering angle of 43 degrees. I think most cars today
>> stop at 38 degrees.
>> Anyway it is a 2-door car somewhat smaller than a taxi.
>
> Oddly, there is a factor to consider with those two vehicles - the type
> of steering. They both have 'old-fashioned' systems, using a steering box
> and links. Using a rack and pinion box might make it more difficult to
> achieve the articulation needed.
>
> As an aside, the (non-commercial) vehicle with the worst turning circle I
> have ever driven is a LR 110; it completely caught me out the first time
> I drove one!
>
> Chris
>

you get used to it. but worse than those is the ferrari 308, it can be
very time consuming to get into a parking space.

[Chris Whelan]

On Sun, 13 Apr 2014 10:04:22 +0100, Mrcheerful wrote:

[...]

> you get used to it. but worse than those is the ferrari 308, it can be
> very time consuming to get into a parking space.

308 between kerbs is 39 feet, 110 is 44.

Incidentally, the LR 130 is 50 feet!

I realise there would be other difficulties with the Ferrari however.

Chris

--
Remove prejudice to reply.

[Mrcheerful]

On 13/04/2014 10:19, Chris Whelan wrote:
> On Sun, 13 Apr 2014 10:04:22 +0100, Mrcheerful wrote:
>
> [...]
>
>> you get used to it. but worse than those is the ferrari 308, it can be
>> very time consuming to get into a parking space.
>
> 308 between kerbs is 39 feet, 110 is 44.
>
> Incidentally, the LR 130 is 50 feet!
>
> I realise there would be other difficulties with the Ferrari however.
>
> Chris
>

certainly the ferrari seems much worse and lack of visibility does not help.

best big car I had for parking was the mk2 granada estate, good lock and
excellent visibility coupled with square corners you could see, meant it
would go in gaps just a couple of foot longer than the car. Nobody has
mentioned volvo 240, they had amazing steering angles and could fit in
tight spaces, again helped by squareness and visibility.

[LumpHammer]

On 13/04/2014 11:01, Mrcheerful wrote:
> On 13/04/2014 10:19, Chris Whelan wrote:
>> On Sun, 13 Apr 2014 10:04:22 +0100, Mrcheerful wrote:
>>
>> [...]
>>
>>> you get used to it. but worse than those is the ferrari 308, it can be
>>> very time consuming to get into a parking space.
>>
>> 308 between kerbs is 39 feet, 110 is 44.
>>
>> Incidentally, the LR 130 is 50 feet!
>>
>> I realise there would be other difficulties with the Ferrari however.
>>
>> Chris
>>
>
> certainly the ferrari seems much worse and lack of visibility does not
> help.
>
> best big car I had for parking was the mk2 granada estate, good lock and
> excellent visibility coupled with square corners you could see, meant it
> would go in gaps just a couple of foot longer than the car. Nobody has
> mentioned volvo 240, they had amazing steering angles and could fit in
> tight spaces, again helped by squareness and visibility.

I agree with the Volvo 240, the one I learned to drive in could turn
very tightly in car parks. I found it easier to park than a Rover Metro.

[Dave Plowman (News)]

In article <lidj8q$ha3$***@dont-email.me>,
Chris Whelan <***@prejudicentlworld.com> wrote:
> >> Ever owned a Triumph Herald?
> >
> > No. I have seen its turning circle quoted as 25' and also 26'4""
> > That requires a steering angle of 43 degrees. I think most cars today
> > stop at 38 degrees.
> > Anyway it is a 2-door car somewhat smaller than a taxi.

> Oddly, there is a factor to consider with those two vehicles - the type
> of steering. They both have 'old-fashioned' systems, using a steering
> box and links. Using a rack and pinion box might make it more difficult
> to achieve the articulation needed.

The Herald had R&P.

--
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Dave Plowman ***@davenoise.co.uk London SW
To e-mail, change noise into sound.