Harper Adams 4x4 Videos

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Freediscoranger said:
not sure of the specific rating of the strain guage but its used a lot with the tractors and is a pretty huge chunk of metal. another thing we used it for recently was to lift a lightweight up with a telle-handler calculating center of gravity, so it can easily take the weight of a vehicle hanging off the end.

as for the tractive effort on tarmac... im sure we could try that for one of the next tutorials :D
a rough estimate can be worked out if you had the shear force of the rubber on tarmac (assuming the vehicle can break traction)
in our off-road test the weight of the vehicle had far more effect than the track size (due to such a small shear force)

i hope that was faily clear :D weve literally only done that session on that topic :D:D
Click to expand...
while i agree that the vehicle weight will have a bearing on tyre shear force, the surface under the tyre must also be taken into account.
where you guys can pretty much load the shear force with the tractor to take readings, it would be interesting to see the maximum forces generated on tarmac, then compare them with daily life such as loading a 3.5ton ifor to capacity and taking the readings setting off on level at traffic lights, fast pull outs at congested runabouts, initial inertia when setting off up a 1:3 road etc.

do you not have to document your test instruments for stuff like that?
(we do in the real world!) make, model, rating, etc

finally, you seem to have stirred up a bit of a hornets nest here......
best of luck!
 
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pca42 said:
Could have done with some better implements than a tiny axe and a blunt bow saw tbh! lol
Click to expand...

Perhaps Harper 4x4 should invest in one of these

[ame=http://www.youtube.com/watch?v=FvAI7-Qa2Io]V8 Chainsaw 6 - YouTube[/ame]


That would clear most obstructions, I should think
 
pca42 said:
Could have done with some better implements than a tiny axe and a blunt bow saw tbh! lol
Click to expand...

Pete i think its time to bury the hatchet on that whole forrest of trolls :p

nrgserv said:
while i agree that the vehicle weight will have a bearing on tyre shear force, the surface under the tyre must also be taken into account.
where you guys can pretty much load the shear force with the tractor to take readings, it would be interesting to see the maximum forces generated, then compare them with daily life such as loading a 3.5ton ifor to capacity and taking the readings setting off on level at traffic lights, fast pull outs at congested runabouts, initial inertia when setting off up a 1:3 road etc.

do you not have to document your test instruments for stuff like that?
(we do in the real world!) make, model, rating, etc

finally, you seem to have stirred up a bit of a hornets nest here......
best of luck!
Click to expand...

yea we did document all the results they were on the board pic at the end of my vid
 
Knowing you though Steg, you'd build a chainsaw with a large american straight six turbo diesel engine, and then when I say it would be too heavy to lift and impractical to use as a chain saw, you'd reply "it'd be reet mon".
 
NRS91 said:
Pete i think its time to bury the hatchet on that whole forrest of trolls :p



yea we did document all the results they were on the board pic at the end of my vid
Click to expand...
didnt see the rating!
does tractive effort provide more force than a lightwieght suspended from a telehandler?
and was it the centre of gravity you wanted to find, or the point of equilibrium?
 
pca42 said:
Knowing you though Steg, you'd build a chainsaw with a large american straight six turbo diesel engine, and then when I say it would be too heavy to lift and impractical to use as a chain saw, you'd reply "it'd be reet mon".
Click to expand...

fair play mon! besides a Cummins 6BT aint THAT heavy :p
who needs a gym ;)
 
nrgserv said:
didnt see the rating!
does tractive effort provide more force than a lightwieght suspended from a telehandler?
and was it the centre of gravity you wanted to find, or the point of equilibrium?
Click to expand...

which rating?
and i cant remember
but we were calculating CoG
 
nrgserv said:
didnt see the rating!
does tractive effort provide more force than a lightwieght suspended from a telehandler?
and was it the centre of gravity you wanted to find, or the point of equilibrium?
Click to expand...

The best tractive effort we managed on the day was about 1.2 tonnes, from the Disco, and the lightweight is around 1.4 tonnes iirc.

The lightweight was sat on digital scale pads (one under each wheel) as it was being lifted, so we were interested in what the weight over the rear axle was doing as the front was being lifted.
 
nrgserv said:
:scratching_chin:
and how does that tell you the cog?
Click to expand...

i must admit it was before xmas and i cant remember the exacts but i think the wheel weights give you side to side and front to back alignment of the CoG then the lifting with the load cell gives you the height of the CoG (cant remember exactly how but it was some comparison between the load cell reading and the rear wheel weights)
 
load cells under the wheels will give you axle weights.
lifting the front will give a transfer weight to the remaing axle
and it will alter nearer to perpendicular. (assuming you can balance it perpenducular without weight on the telehandler)
it could be worked out at what the point equilibrium is reached, but not tell you where cog is on the lightweight.
cog is by definition, the centre. ie, one point.
would be interested as to how this is calculated.
 
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nrgserv said:
load cells under the wheels will give you axle weights.
lifting the front will give a transfer weight to the remaing axle
and it will alter nearer to perpendicular. (assuming you can balance it perpenducular without weight on the telehandler)
it could be worked out at what the point equilibrium is reached, but not tell you where cog is on the lightweight.
cog is by definition, the centre. ie, one point.
would be interested as to how this is calculated.
Click to expand...

one pad under each wheel. as its lifted the weight on the rear axle increases. since there was a pad under each wheel the weight on each side wasnt quite the same so we could seee how the CoG was shifted from one side to another. as it was lifted until the telehandler was simply supporting the vehicle in the upright way the CoG was calculated lengeth ways ont eh vehicle. put them together and you have the single point.
the idea of that practicle wasnt get the CoG located down the the millimeter but simply show where it roughly is and see what factors we can spot which have altered it from dead center so we get a better idea of how to design vehicles taking into account all the things we spotted.
Its fairly obvious stuff really but was mostly just interesting for the people who didnt really know anything about them see what they look like.
 
ah! so did you get a point on the lightweight that is the approx cog, or an angle of which cog was in equilibrium?

so out of interest, i reckon the front axle bears more weight on a horizontal plain,
at what point on an angle going uphill do the weight shift to the back axle?
ie, how steep does it have to be?

an if it wants to get more testicle, would tractive force be lost before rotary motion of the back wheel pivots the motor over itself!
 
Do you get taught how to plan laning trips properly, liaise with the local councils right of way officers, etc. Or do the "teachers" just have set routes you can go and play on?

Looks like you get to play around a lot with your landies! Looks great fun... beats spending all day in a lecture theatre that's for sure.
 
Bump said:
Do you get taught how to plan laning trips properly, liaise with the local councils right of way officers, etc. Or do the "teachers" just have set routes you can go and play on?

Looks like you get to play around a lot with your landies! Looks great fun... beats spending all day in a lecture theatre that's for sure.
Click to expand...

not be playing in them now, looks like someone has confiscated them, lol http://www.landyzone.co.uk/lz/f43/h253cbv-red-defender-90-200tdi-stolen-6-7th-feb-2012-a-177709.html
 
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