Checking your height

[scanny77]

Coffeeholic:
But you are likely making unnecessary detours.

probably but i would rather detour than chance it. i dont trust bridge heights either. they arent always accurate either or are you suggesting i measure them too?

[coffeeholic]

scanny77:

Coffeeholic:
But you are likely making unnecessary detours.

probably but i would rather detour than chance it. i dont trust bridge heights either. they arent always accurate either or are you suggesting i measure them too?

I would have thought one stupid question from you would be enough but it appears not. No, it isn’t your responsibility to measure bridges. If you hit a bridge because it is incorrectly marked that aint your problem. What is your responsibility is to know the height of your vehicle, which you clearly do not know, while you are on the road. You don’t trust the bridge height signs but you trust the markings on the headboard, even though they are more likely to be wrong and can never be accurate anyway due to the differing units/5th wheel combinations that can be used. How does that work then?

Given you normal posts on defecting motors for the slightest thing, being keen to do everything exactly by the book etc, it seems strange to me you are happy to drive around in ignorance of the size of your vehicle.

[scanny77]

even your so called plan is flawed. the height on the headboard measures the height of the headboard. if your fifth wheel is high then your trailer is then a different height to to the additional angle of the headboard. it will not be vertical therefore it will be higher than marked in which case, measureing the height of the fifth wheel is rendered innaccurate too.

FYI, our trailers are 13’6 so i avoid any bridges under 14’

and dont even think about saying that you lot measure your truck every time you pick up a trailer or different unit. there is no way in hell anyone does that. i have never seen anyone pull a measureing device out. EVER!

[montana_man]

Well if your gonna go down that road of thought Richie boy do you include into your equation the fact that the height on a “sloping trailer” may have been measured on a shorter or longer wheelbased unit and thus still not accurate. Or if it’s a centre lift unit then does it adjust the height when lifted like a "Scanny does ■■

I suggest if have such a HUGE concern about this that you stick to rigids BUT oh dear only ones with air suspension and therefore a load consistent height.

Oh Oh just a thought here What if you do measure the height of your unit and trailer and the air suspension hadn’t settled correctly Oh and what if you measured it but the unit had a fault with the suspension which meant it may alter during the journey Perhaps the previous driver didn’t defect the it despite the light, warning beep and the fact it just didn’t feel right

Well that’s it I am going to march straight into the transport office tomorrow and demand that they route my 13’10" truck and trailer around any bridge under 30’ just in case

P.S. it’s only marked in the cab at 13’10’ as a worse case scenario i.e. close coupled trailer and centre lift up. I know for a fact it will go under a lot lower bridges at the flick of a lift axle switch

Perhaps you shpuld share your concerns with your employers and see if they can give you a better answer than ALL the above

and FYI , I DO carry a tape in the truck just in case and had to use last week at a farm collection with an unmarked gantry Worth the effort as I had to drop the unit air to creep under BUT not the trailer as mine slopes too

[scanny77]

montana man:
I suggest if have such a HUGE concern about this

i dont. i simply asked a question regarding something i have seen mentioned a few times but i have never been told about. yet again, its been blown all over the place hence the foxtrot uniform attitude. dont dish it out if you cant take it back

regarding the topic, it seems that there is no conclusive answer due to all other factors that affect heights so all this has been pointless

[montana_man]

scanny77:

montana man:
I suggest if have such a HUGE concern about this

i dont. i simply asked a question regarding something i have seen mentioned a few times but i have never been told about. yet again, its been blown all over the place hence the foxtrot uniform attitude. dont dish it out if you cant take it back

WTF get a grip man

You obviously ARE concerned enough to take detours at your employers expense to avoid bridges that you could be at least 6 inches clear of getting under

regarding the topic, it seems that there is no conclusive answer due to all other factors that affect heights so all this has been pointless

The conclusive aswer lies at the TOP OF THIS THREAD

here’s another reminder :

[denis_f]

montana man:
The conclusive aswer lies at the TOP OF THIS THREAD

here’s another reminder :

as our official pedant is awol

you might be better off with one of these

[montana_man]

Supplemental pedantry is most welcome Denis

There’s far to much in this thread for just one

[coffeeholic]

He still won’t get it, it seems you are being too subtle. Maybe a slightly more direct approach is called for.

scanny77:
how do you physically check the height of your wagon?

MEASURE THE [ZB]ING THING

THIS thread is interesting, comparing a quote from this thread with on from that.

scanny77:
i have never seen anyone pull a measureing device out. EVER!

scanny77:
i have seen car transporter drivers checking their height with a folding stick of some kind

[coffeeholic]

scanny77:
even your so called plan is flawed. the height on the headboard measures the height of the headboard.

Correct if the headboard just gives the body height, as with the trailer you mentioned when you started this thread, then that will be the body height, not the overall height. Don’t tell me we are making progress after all this time?

scanny77:
if your fifth wheel is high then your trailer is then a different height to to the additional angle of the headboard.

Correct, the overall height will be different but the height of the body as marked will still be the same.

scanny77:
it will not be vertical therefore it will be higher than marked

Err, no. If the headboard is marked as being 10 feet then it will be 10 feet regardless of what angle you put it at, tilting it won’t make the headboard grow.

scanny77:
in which case, measureing the height of the fifth wheel is rendered innaccurate too.

Which is why I said measure from the ground to the body and add that to the height of the actual body to get the overall height. If you measure straight down to the ground and add the body height to this measurement, than you will be slightly over due to the trailer leaning back a little but if you take that as your running height it gives you a tiny bit of wiggle room.

Think of it this way. If you have a 6 foot stick and it is standing dead vertical, the top of the stick is 6 feet from the ground. If you now tilt the stick slightly from the vertical the top will now be a little less than 6 feet from the ground but the stick is still a 6 foot stick. If you now stand the stick vertically on a wall the top will now be more than 6 foot from the ground but the problem is you cannot reach the top of the stick to measure it. If you measure the wall and it is 3 feet you now know the overall height of the stick and the wall is 9 feet. If you tilt the stick slightly off the vertical the top of the stick will now be a little less than 9 feet from the ground. However the stick and wall combination will pass under anything that is greater than 9 feet, regardless of whether the stick is vertical or tilted slightly. So if a headboard is marked as being 10 feet and the distance from the body to the ground is 3 foot 6 inches then the truck will pass under anything greater than 13’6" regardless of the angle the headboard is at, as long as it is tilted back. If the headboard is tilted forward then the front would pass but the back would catch, but you could see by looking that the back is higher and you would measure there instead - you obviously would always measure the highest part.

[scanny77]

you are still missing something. we are not talking about a stick. if we were, i would agree. the fact that we are talking about a box changes it

for simplicity, use a 45 degree angle. the headboard would be the same LENGTH but the height would be higher due to the angle and the point at which it joins the fifth wheel. there are mathematical ways to work it out but i dont know what they are and i cant be arsed finding out. the simple way is to use a plumb line from the highest point to the base of the body then measure from that point to the ground (or all the way if you can physically do it. the depth of the king pin will have a huge impact on the angle and therefore height of the trailer. the deeper the pin, the greater the angle, the higher the trailer is at the front

unless you also carry a spirit level and park on level ground with a fifth wheel height of exactly the same as the underside of the trailer, your height is going to be different to simply measureing the height of the fifth wheel and adding it to the height of the headboard

[zetorpilot]

The way this thread has gone I’m surprised no-one has suggested the “easy” way:

1. Borrow a sextant from a passing ship’s captain, and a tape measure from Montana Man.

2. Stand a known distance away from the highest point of your wagon, we will call this distance “D”. Use Montana Man’s tape measure for this.

3. Learn how to use sextant.

4. Use sextant to measure angle to highest point, we will call this angle “A”

5. Use trignometry to calculate height difference (let’s call this “H”) between highest point of wagon and the hight above ground of the sextant. In this case remembering my school days about 30 years ago, subsituting the letters we have used above into the formula gives us H = D(tan(A))

6. Now we have H, we need to add the height of the sextant above the ground, for practical purposes the height of your eyeball above the ground. Montanta Man’s tape measure can be used to measure this too. If we call this height “h” then we can simply deduce the height of the wagon as h+H.

The formula as a whole is of course Height of Wagon = D(tan(A))+h

Easy or what??

7. Return sextant to ship’s captain, and tape measure to Montana Man.

[tony1968]

scanny77:
for simplicity, use a 45 degree angle. the headboard would be the same LENGTH but the height would be higher due to the angle and the point at which it joins the fifth wheel. there are mathematical ways to work it out but i dont know what they are and i cant be arsed finding out. the simple way is to use a plumb line from the highest point to the base of the body then measure from that point to the ground (or all the way if you can physically do it. the depth of the king pin will have a huge impact on the angle and therefore height of the trailer. the deeper the pin, the greater the angle, the higher the trailer is at the front

I disagree, at a 45 degree angle the headboard would actually be half the height, measured from the bottom of the headboard to the top of the headboard. The perfect vertical is actually the worst case scenario so you can trust the measurement written on the headboard. All you now need to do is measure the distance from the ground to the bottom of the headboard and add the two together. As this is a real world situation your measurement will be correct for that trailer, sitting on that 5th wheel on that truck. Only thing that can go wrong is the ride height and if you’ve levellled that first you’ll be fine.

I’ll admit I’ve seen a few streamlined deckers about where the headboard is a good 3ft lower than the roof line but if you’re pulling one of those you can probably assume you can’t get under any low bridges!

[krankee]

Zetorpilot:
The formula as a whole is of course Height of Wagon = D(tan(A))+h

Easy or what??

That’s assuming that all measurements/sightings, apart from feet to eyeball, are taken from the same flat surface.

7. Return sextant to ship’s captain, and tape measure to Montana Man.

Nah. They wouldn’t miss them.

[zetorpilot]

Krankee:
That’s assuming that all measurements/sightings, apart from feet to eyeball, are taken from the same flat surface.

Strictly speaking, Krankee, you’re right. I haven’t for example taken into account the curvature of the earth. Without delving into the realms of spherical trignometry, I’ll just say that this would tend to make the wagon appear to be a few microns lower than it really is.

BUT we also have to factor in the fact that the wagon is going to be moving when actually going under a bridge and the assosciated relativistic mass increase would load the suspension by a few fractions of a gramme and therefore surely cancel this error out.

It’s not commonly known, but many believe Einstein first suspected the existance of relativistic mass increase - namely the phenomenon whereby objects become heavier the faster they travel - in 1905 as a result of his noticing apparently anomalous physics of certain Dutch and Irish horseless carriages.

[coffeeholic]

scanny77:
you are still missing something. we are not talking about a stick. if we were, i would agree. the fact that we are talking about a box changes it

Err no it doesn’t

scanny77:
for simplicity, use a 45 degree angle. the headboard would be the same LENGTH

Exactly and this thread was started about a trailer that only had the headboard height on it.

scanny77:
but the height would be higher due to the angle

No it would not be higher than when the headboard is vertical. If it is tilted the top front corner of the headboard will be nearer the ground than when it is vertical.

scanny77:
and the point at which it joins the fifth wheel.

Which is why I’ve never said measure at that point. When the trailer is tilted back slightly due to the 5th wheel the front bottom corner of the headboard will be the highest point of the base of the body from the ground and you would obviously measure from there.

scanny77:
there are mathematical ways to work it out but i dont know what they are and i cant be arsed finding out. the simple way is to use a plumb line from the highest point to the base of the body

You already know the height of the body as it is written on the headboard

scanny77:
then measure from that point to the ground

Which has already been mentioned on this thread but you haven’t spotted until now.

scanny77:
(or all the way if you can physically do it.

It’s easy enough to do that if you either get someone to hold the oither end of the tape or you do it in sections and add them together. Something else that has already been mentioned.

scanny77:
the depth of the king pin will have a huge impact on the angle and therefore height of the trailer. the deeper the pin, the greater the angle, the higher the trailer is at the front

Exactly, which again is why I never said to measure at that point. You would look at the trailer and measure the highest point. Measuring to the ground from the front corner of the head board and adding that to the body height will give you a slight over reading due to the headboard being tilted back. However if you take that total, say 13’ 6" and don’t try to get under anything less than 13’ 6" then you will be OK as you will in fact be a little less than 13’ 6".

scanny77:
unless you also carry a spirit level and park on level ground with a fifth wheel height of exactly the same as the underside of the trailer, your height is going to be different to simply measureing the height of the fifth wheel and adding it to the height of the headboard

Again, it was never said to measure the 5th wheel, you measure the highest point, normally at the headboard, unless it is a low unit and it is carrying the trailer tilted back when you would obviously measure from the back to the ground.

[transporter13]

and dont even think about saying that you lot measure your truck every time you pick up a trailer or different unit. there is no way in hell anyone does that. i have never seen anyone pull a measureing device out. EVER!

Actually… I DO

Hit a bridge once…copper tried to do me at the scene, I argued the toss as i hadnt seen a height marker on the bridge therefore assuming the bridge was at least 16’…Turned out that I was wrong and that the bridge height was only 15’9". The road had been resurfaced days previous. Only got away with it after showing the plod with my heightstick. Got a letter from the police saying that no further action was intended. Made a mess of the new mondeo that was up on the top deck lol

[backysteve]

2 pages to answer such an easy question. I worked it our by accident. I had sent the wife up top to clear something off the top of the trailer, while up there she lost her footing and fell off and there was the eureka moment. Knowing exactly how much she weighed i get her to jump off the trailor and using a specially calibrated stop watch i time her descent to tarmac. Then use a special mathamatical equation to work out height of trailer. Just simple physics really.

[dieseldave]

backysteve:
2 pages to answer such an easy question. I worked it our by accident. I had sent the wife up top to clear something off the top of the trailer, while up there she lost her footing and fell off and there was the eureka moment. Knowing exactly how much she weighed i get her to jump off the trailor and using a specially calibrated stop watch i time her descent to tarmac. Then use a special mathamatical equation to work out height of trailer. Just simple physics really.

PMSL

That was a great theory and I was just getting to grips with it until I saw this:

Knowing exactly how much she weighed…

Then it all unravelled, because nobody ever gets told how much a woman weighs…

[zetorpilot]

backysteve:
…Knowing exactly how much she weighed…

Oh dear - you are forgetting Galileo’s famous experiment conducted on the leaning tower of Pisa about 400 years ago. He showed that a light object and a heavy object fall at the same rate - contradicting the commonly held belief of the time that heavy objects fall faster.