OT Trailer ground clearance.

Yes, its Landrover OT, except its going to be a landie pulling it on its
trials, but I have just been offered a project to design and build six
plus pieces of kit that will be hauled around on their own custom
trailers, then, when they arrive on site, they are lowered through the
floor of the trailer and sit on the ground surrounded by their support
gear in the rest of the trailer but isolated for vibration purposes from
it.

For technical reasons, I want the ground clearance of the towed rig to
be "as low as possible". The question is what IS permissible ? Is there
actually a legal limit ?

Ta

Steve

"steve Taylor" <[email protected]> wrote in message
news:[email protected]...

> For technical reasons, I want the ground clearance of the towed rig to
> be "as low as possible". The question is what IS permissible ? Is there
> actually a legal limit ?
>
> Ta
>
> Steve

dunno but you need to calculate the height of the average bit of road debris
and weigh up against the sensitivity of kit and repair issues.

4 inch plus a thou.... (house brick and a bit!)

Of course you could develope an evil streak and build in some deliberate
design flaws (I can say that as it's very on topic!) ;0)

Lee D

steve Taylor wrote:
> Yes, its Landrover OT, except its going to be a landie pulling it on its
> trials, but I have just been offered a project to design and build six
> plus pieces of kit that will be hauled around on their own custom
> trailers, then, when they arrive on site, they are lowered through the
> floor of the trailer and sit on the ground surrounded by their support
> gear in the rest of the trailer but isolated for vibration purposes from
> it.
>
> For technical reasons, I want the ground clearance of the towed rig to
> be "as low as possible". The question is what IS permissible ? Is there
> actually a legal limit ?

Are you going to have suspension on the trailer or will the wheels be
solid mounted? And is it possible to have an axle full width across the
trailer?

--
EMB

EMB wrote:

> Are you going to have suspension on the trailer or will the wheels be
> solid mounted? And is it possible to have an axle full width across the
> trailer?

Its a pretty delicate cargo, so suspension will be important. Axle
across ? Possibly. Is that better than separate units ?

Steve
>

steve Taylor wrote:
> EMB wrote:
>
>
>>Are you going to have suspension on the trailer or will the wheels be
>>solid mounted? And is it possible to have an axle full width across the
>>trailer?
>
>
> Its a pretty delicate cargo, so suspension will be important. Axle
> across ? Possibly. Is that better than separate units ?
>
> Steve
>
What I'd do is use duratorque suspension units (I assume they're
available in the UK - or at least something like them) as they let you
get close to the ground and still have good suspension.

http://www.trojan.co.nz/PRD_Dts.htm

If you use a full width duratorque axle you can mount it on an eccentric
and make it rotate on a couple of hydraulic rams to drop the entire
trailer to the ground when it's stationary. I've drawn a horrible
usenet picture below - hope it makes sense (end on view of axle - same
setup both ends)



II <--- ram
II
-------------------------
| |
| O |-| <--- axle |<--- steel pivot plate
| ^ |_| |
|___|_____________________
|
pivot point




--
EMB

On or around Thu, 18 Aug 2005 20:06:59 +0100, steve Taylor
<[email protected]> enlightened us thusly:

>Yes, its Landrover OT, except its going to be a landie pulling it on its
>trials, but I have just been offered a project to design and build six
>plus pieces of kit that will be hauled around on their own custom
>trailers, then, when they arrive on site, they are lowered through the
>floor of the trailer and sit on the ground surrounded by their support
>gear in the rest of the trailer but isolated for vibration purposes from
>it.
>
>For technical reasons, I want the ground clearance of the towed rig to
>be "as low as possible". The question is what IS permissible ? Is there
>actually a legal limit ?

don't think so. there are practical limits, of course - for a wide-track
trailer, I'd aim at 6" in the centre, minimum. by wide-track, I mean 6'
plus.
--
Austin Shackles. www.ddol-las.net my opinions are just that
Satisfying: Satisfy your inner child by eating ten tubes of Smarties
from the Little Book of Complete B***ocks by Alistair Beaton.

On or around Thu, 18 Aug 2005 22:07:56 +0100, steve Taylor
<[email protected]> enlightened us thusly:

>EMB wrote:
>
>> Are you going to have suspension on the trailer or will the wheels be
>> solid mounted? And is it possible to have an axle full width across the
>> trailer?
>
>Its a pretty delicate cargo, so suspension will be important. Axle
>across ? Possibly. Is that better than separate units ?

Separate units can be changed more easily in the event of a failure. You
can also do more with mounting them to minimise height - for a smooth ride,
you want to be looking at largish wheels, at least 14", in addition to
speccing the suspension units right for the job. In order to get the floor
height lower you may want to look at mounting the units the wrong way up or
the wrong way 'round. normally, the arms are trailing and point downwards
at 30-45 degrees, but I see no reason why they have to, as such. Might want
to look at ratings if you mount them otherwise, although the movement is not
all that great anyway. funny mounting of axles is easier with separate
units, but of course alignment is important... axles in one piece are easier
to align but do have a straight tube all the way across at a bit more than
hub centre height (unless you mount 'em upside down I suppose).

dunno why I'm telling you all this, mind, 'cos one of my many hats is
"trailer-builder", when I can find people prepared to pay for 'em. Most
people instead go for a rusty old heap and then spend alsmost as much as
it'd have cost 'em to have me build one in repairing it...

--
Austin Shackles. www.ddol-las.net my opinions are just that
"Quos deus vult perdere, prius dementat" Euripedes, quoted in
Boswell's "Johnson".

"steve Taylor" <[email protected]> wrote in message
news:[email protected]...
> EMB wrote:
>
> > Are you going to have suspension on the trailer or will the wheels be
> > solid mounted? And is it possible to have an axle full width across the
> > trailer?
>
> Its a pretty delicate cargo, so suspension will be important. Axle
> across ? Possibly. Is that better than separate units ?
>
> Steve
> >
In my younger and some would say sillier days I used a very low
trailer designed specifically to tow a car whilst the tow vehicle was
setup with a camera rig for TV commercials.

It basically had a wheel in each corner, using a rubber monobloc
suspension with stub axles.

The deck was lower than the centre of the axles to give the impression
that the vehicle was on the road and being driven. There was
the ability to raise and lower the deck by the use of four motorcycle
style shock absorbers as well.

The front wheels steered by means of the drawbar and various linkages
which somehow we connected to the vehicle on the trailer steering so that
the "driver's steering wheel" turned (to make it real - bear in mind that
the advertising agencies were overrun with "art directors" back in the
80s).

Austin Shackles wrote:
>
> dunno why I'm telling you all this, mind, 'cos one of my many hats is
> "trailer-builder", when I can find people prepared to pay for 'em. Most
> people instead go for a rusty old heap and then spend alsmost as much as
> it'd have cost 'em to have me build one in repairing it...
>
You have that problem too - it's obviously a worldwide syndrome.


--
EMB

On or around Fri, 19 Aug 2005 09:43:26 +1200, EMB <[email protected]>
enlightened us thusly:

>steve Taylor wrote:
>> EMB wrote:
>>
>>
>>>Are you going to have suspension on the trailer or will the wheels be
>>>solid mounted? And is it possible to have an axle full width across the
>>>trailer?
>>
>>
>> Its a pretty delicate cargo, so suspension will be important. Axle
>> across ? Possibly. Is that better than separate units ?
>>
>> Steve
>>
>What I'd do is use duratorque suspension units (I assume they're
>available in the UK - or at least something like them) as they let you
>get close to the ground and still have good suspension.
>
>http://www.trojan.co.nz/PRD_Dts.htm

Indespension or Peak in this country. simialr system though.

>
>If you use a full width duratorque axle you can mount it on an eccentric
>and make it rotate on a couple of hydraulic rams to drop the entire
>trailer to the ground when it's stationary. I've drawn a horrible
>usenet picture below - hope it makes sense (end on view of axle - same
>setup both ends)

that's what my big trailer does, except that the axle beam is mounted in
circular things and the beam just rotates. >
--
Austin Shackles. www.ddol-las.net my opinions are just that
Confidence: Before important work meetings, boost your confidence by
reading a few pages from "The Tibetan Book of the Dead"
from the Little Book of Complete B***ocks by Alistair Beaton.

On or around Fri, 19 Aug 2005 09:55:57 +1200, EMB <[email protected]>
enlightened us thusly:

>Austin Shackles wrote:
>>
>> dunno why I'm telling you all this, mind, 'cos one of my many hats is
>> "trailer-builder", when I can find people prepared to pay for 'em. Most
>> people instead go for a rusty old heap and then spend alsmost as much as
>> it'd have cost 'em to have me build one in repairing it...
>>
>You have that problem too - it's obviously a worldwide syndrome.

people are strange... as they said in the song.

chap up the road spent 600 quid on an unsuitable trailer (too heavy for the
car) with a rotten floor, dubious mechanicals and no gates. He then paid me
about 100 quid to repair the floor and make new gates (livestock trailer)
and paid someone else to fix the brakes and replace the tyres. For about
200 quid more total he could have had a purpose built one which would have
been a lot better suited to the job...
--
Austin Shackles. www.ddol-las.net my opinions are just that
Confidence: Before important work meetings, boost your confidence by
reading a few pages from "The Tibetan Book of the Dead"
from the Little Book of Complete B***ocks by Alistair Beaton.

Steve

Have a look at these two sites. The NTTA one is good reference.

http://www.dft.gov.uk/stellent/groups/dft_roads/documents/pdf/dft_roads_pdf_506866.pdf

http://www.ntta.co.uk/law/law/dimensions.htm

Mike

"steve Taylor" <[email protected]> wrote in message
news:[email protected]...
> Yes, its Landrover OT, except its going to be a landie pulling it on its
> trials, but I have just been offered a project to design and build six
> plus pieces of kit that will be hauled around on their own custom
> trailers, then, when they arrive on site, they are lowered through the
> floor of the trailer and sit on the ground surrounded by their support
> gear in the rest of the trailer but isolated for vibration purposes from
> it.
>
> For technical reasons, I want the ground clearance of the towed rig to
> be "as low as possible". The question is what IS permissible ? Is there
> actually a legal limit ?
>
> Ta
>
> Steve

Mike Derrick wrote:
> Steve
>
> Have a look at these two sites. The NTTA one is good reference.
>
> http://www.dft.gov.uk/stellent/groups/dft_roads/documents/pdf/dft_roads_pdf_506866.pdf
>
> http://www.ntta.co.uk/law/law/dimensions.htm
Thanks for those Mike - very useful.

Steve