In article ,
Chris J Dixon wrote:
I need to do occasional stepladder work - trimming trees and my
neighbour's laurel, plus cleaning the caravan roof and seasonally
draping Christmas lights. My existing stepladder is not really
high enough, and stability can also be marginal.

I am wondering if it is time, as a precautionary investment to
reduce the risk of injury, to get something better.

The Rolls Royce solution might be something like the 10 ft
version of this:
https://www.niwaki.com/store/niwaki-tripod-ladder/

A tripod ladder is a bad idea, as they are a lot less stable than
a corresponding quadrupod one. We bought an industrial-grade one
from Mackays at 150 quid (versus 50 quid for the 'domestic') and
have not regretted it.


Regards,
Nick Maclaren.

On 21/02/17 15:30, Nick Maclaren wrote:
In article ,
Chris J Dixon wrote:
I need to do occasional stepladder work - trimming trees and my
neighbour's laurel, plus cleaning the caravan roof and seasonally
draping Christmas lights. My existing stepladder is not really
high enough, and stability can also be marginal.

I am wondering if it is time, as a precautionary investment to
reduce the risk of injury, to get something better.

The Rolls Royce solution might be something like the 10 ft
version of this:
https://www.niwaki.com/store/niwaki-tripod-ladder/

A tripod ladder is a bad idea, as they are a lot less stable than
a corresponding quadrupod one. We bought an industrial-grade one
from Mackays at 150 quid (versus 50 quid for the 'domestic') and
have not regretted it.


Regards,
Nick Maclaren.


Can you explain why tree surgeons almost always have a tripod ladder?

They have a very wide area of footing and 3 legs is inherently stable on
unplanar ground.

In article ,
Tim Watts wrote:

Can you explain why tree surgeons almost always have a tripod ladder?

Tripod ladders are easier to get closer to trees.

They have a very wide area of footing and 3 legs is inherently stable on
unplanar ground.

You're missing the point. For a given leg separation, the distance
from the centre (at ground level) to the closest point outside the
triangle is much less than it is for the quadrilateral. Therefore,
the ladder will fall over for a much lower imbalance in the weight
or sideways force.


Regards,
Nick Maclaren.

Nick Maclaren wrote:

You're missing the point. For a given leg separation, the distance
from the centre (at ground level) to the closest point outside the
triangle is much less than it is for the quadrilateral. Therefore,
the ladder will fall over for a much lower imbalance in the weight
or sideways force.

Isn't the whole point that the design under consideration doesn't
have the same leg separation as a conventional ladder. For
instance, the 3 m ladder is 1.45 m wide at the base.

https://www.niwaki.com/store/niwaki-tripod-ladder/

Chris
--
Chris J Dixon Nottingham UK


Plant amazing Acers.

In article ,
Chris J Dixon wrote:

You're missing the point. For a given leg separation, the distance
from the centre (at ground level) to the closest point outside the
triangle is much less than it is for the quadrilateral. Therefore,
the ladder will fall over for a much lower imbalance in the weight
or sideways force.

Isn't the whole point that the design under consideration doesn't
have the same leg separation as a conventional ladder. For
instance, the 3 m ladder is 1.45 m wide at the base.

https://www.niwaki.com/store/niwaki-tripod-ladder/

Ah. That would be enough, PROVIDED that the single leg is at a shallow
enough angle. Most step ladders have the non-step legs more vertical
than the other ones, which means the CoG is closer to them - and, if
there is a single one, that leads to instability. From the picture,
that looks the case.


Regards,
Nick Maclaren.

On 21/02/17 17:19, Nick Maclaren wrote:
In article ,
Tim Watts wrote:

Can you explain why tree surgeons almost always have a tripod ladder?

Tripod ladders are easier to get closer to trees.

They have a very wide area of footing and 3 legs is inherently stable on
unplanar ground.

You're missing the point. For a given leg separation, the distance
from the centre (at ground level) to the closest point outside the
triangle is much less than it is for the quadrilateral. Therefore,
the ladder will fall over for a much lower imbalance in the weight
or sideways force.


Regards,
Nick Maclaren.


However, the tripod ladder leg spacings are MUCH larger than 4 legged
ladders - and a 4 legged ladder would be very unstable on non planar ground.

So tripods of a suitable size seem like a win to me for that particular
purpose.

On 21/02/2017 17:19, Nick Maclaren wrote:
You're missing the point. For a given leg separation, the distance
from the centre (at ground level) to the closest point outside the
triangle is much less than it is for the quadrilateral. Therefore,
the ladder will fall over for a much lower imbalance in the weight
or sideways force.

You're missing the point. Unlike a floor in a house a garden isn't a
flat plane. Which means that one leg of a 4 legged ladder is always off
the ground.

And that means it is _less_ stable than a properly designed three legged
one, as it rocks between the two stable configurations...

I have a step ladder with bars across the base of each step. It's great
indoors. Outdoors I have to fiddle around for ages so it doesn't rock,
sometime putting bricks under it

Andy

In article ,
Vir Campestris wrote:

On 21/02/2017 17:19, Nick Maclaren wrote:
You're missing the point. For a given leg separation, the distance
from the centre (at ground level) to the closest point outside the
triangle is much less than it is for the quadrilateral. Therefore,
the ladder will fall over for a much lower imbalance in the weight
or sideways force.

You're missing the point. Unlike a floor in a house a garden isn't a
flat plane. Which means that one leg of a 4 legged ladder is always off
the ground.

And that means it is _less_ stable than a properly designed three legged
one, as it rocks between the two stable configurations...

I have a step ladder with bars across the base of each step. It's great
indoors. Outdoors I have to fiddle around for ages so it doesn't rock,
sometime putting bricks under it

I've only ever seen (on't'telly) tripod ladders in use with
trees/hedges. One was Monty Don doing his Product Placement thing [he's
good at that] when cutting his 15' tall beech hedge[1], with the odd
leg shoved through into the bottom of the hedge -- you couldn't do that
with a 4-legger. "Damn good!" I thought, as a regular hedge trimmer
myself.

Another was when a programme visited an orchard, and they were using the
tripod to pick apples -- perfect.

In both cases, the tree/hedge is giving extra stability to the lad/lass
at the top of the ladder.

John

[1] You never, ever, see a sign of the small army of "assistant
gardeners" who must inhabit Monty's VAST garden at lovely old Long
Meadow. He wouldn't remotely have time, let alone the energy, to do
everything that gets done there. Bloody annoying.

In article ,
Vir Campestris wrote:

You're missing the point. For a given leg separation, the distance
from the centre (at ground level) to the closest point outside the
triangle is much less than it is for the quadrilateral. Therefore,
the ladder will fall over for a much lower imbalance in the weight
or sideways force.

You're missing the point. Unlike a floor in a house a garden isn't a
flat plane. Which means that one leg of a 4 legged ladder is always off
the ground.

And that means it is _less_ stable than a properly designed three legged
one, as it rocks between the two stable configurations...

I am sorry. I was assuming that most people knew how to use a step
ladder safely. One of the critical things to do is to put small
sheets of wood, concrete etc. under the feet to stabilise the ladder.
That is as important for a tripod as a tetrapod, because it is
critical that the ladder does not lean significantly towards one of
the sides of the enclosing polygon. Yes, that is slightly easier for
a tripod, but not doing it for either kind is a serious error.


Regards,
Nick Maclaren.

On 22/02/2017 09:39, Nick Maclaren wrote:
I am sorry. I was assuming that most people knew how to use a step
ladder safely. One of the critical things to do is to put small
sheets of wood, concrete etc. under the feet to stabilise the ladder.
That is as important for a tripod as a tetrapod, because it is
critical that the ladder does not lean significantly towards one of
the sides of the enclosing polygon. Yes, that is slightly easier for
a tripod, but not doing it for either kind is a serious error.

If you have a tripod ladder with well spread legs it will be stable on
any piece of firm, near level ground.

This is not the case for one with 4 or more legs.

I have direct experience of using both types. Do you?

Andy

In article ,
Vir Campestris wrote:

If you have a tripod ladder with well spread legs it will be stable on
any piece of firm, near level ground.

Unless the ground is absolutely level, it will lean, and THAT is the
form of instability it is twice as prone to (relative to its base
dimensions) as a tetrapod ladder. Even a slight lean is a worse danger
than most people realise, because it will put extra weight onto the
downhill legs and, if the ground is not absolutely solid, that will
cause the ladder to lean further as the user climbs it. Quite often
suddenly and unexpectedly.

If tripods did not have a serious disadvantage over tetrapods, they
would have replaced the latter millennia ago, because they are simpler
to make, lighter and (as you say) easier to position.


Regards,
Nick Maclaren.

On Tue, 21 Feb 2017 15:36:38 +0000, Tim Watts wrote:

On 21/02/17 15:30, Nick Maclaren wrote:
In article ,
Chris J Dixon wrote:


The Rolls Royce solution might be something like the 10 ft version of
this: https://www.niwaki.com/store/niwaki-tripod-ladder/

A tripod ladder is a bad idea, as they are a lot less stable than a
corresponding quadrupod one. We bought an industrial-grade one from


Can you explain why tree surgeons almost always have a tripod ladder?

They have a very wide area of footing and 3 legs is inherently stable on
unplanar ground.

Bit like the old milking stools really - far more stable with three legs
than with 4 as they cope with uneven ground far better.

On 21/02/2017 15:36, Tim Watts wrote:
On 21/02/17 15:30, Nick Maclaren wrote:

A tripod ladder is a bad idea, as they are a lot less stable than
a corresponding quadrupod one. We bought an industrial-grade one
from Mackays at 150 quid (versus 50 quid for the 'domestic') and
have not regretted it.


Regards,
Nick Maclaren.


Can you explain why tree surgeons almost always have a tripod ladder?

They have a very wide area of footing and 3 legs is inherently stable on
unplanar ground.

On recent edition of 24 hours in A&E, a tree surgeon arrived in
hospital after falling off a tripod ladder..It was shown in the
program. You can fall off any ladder if you overreach, or cut
something that sprngs back and pushes or pulls you, and/or
the ground is too soft or unstable.