Truck turning circle - URGENT HELP PLEASE!

[B19GRR]

Hi All,

Rather a long an unpleasant story behind all this that I won't bore you with but I need to calculate the kerb to kerb turning circle for a rigid body truck.

At the moment I know that it has a swept turning circle of 15.8, which I assume is like the wall to wall turning circle. It's 8m long but 2.13m wide with a wheel base of 4.35m. The only dimension I don't know is the distance from the front to the front axle centre line which seems quite crucial but for the time being I'm guessing 1.5m.

Here's a pic of what I've got so far:


Am I right to assume that the center of rotation is the rear axle axis, or am I well off?

The truck in question is an Iveco 0816 model - actually a horsebox - if anyone knows any actual data on this model that would be great as the 15.8m swept circle data is from a 0813 model apparently which has a slightly longer wheelbase as well at 4.375m.

Thanks all!!
Rob

[ultimasimon]

Towman !!

[lazyitus]

B19GRR said:

The truck in question is an Iveco 0816 model - actually a horsebox - if anyone knows any actual data on this model that would be great as the 15.8m swept circle data is from a 0813 model apparently which has a slightly longer wheelbase as well at 4.375m. Thanks all!! Rob

Just beware. When I used to sell HGV's, it was common practice to alter chassis lengths and rear axle positions. The 0816 may not be at its original setting particularly if its had different bodies on.

As its a horsebox on a chassis, there is a good chance that the chassis may have had a different body on originally. Most of the horsebox trucks we used to deal with were new horsebox bodies put on older chassis.

I know this doesn't directly answer your question but it may have some significance?

[GreenV8S]

The picture looks right, but I think it will be difficult to work it out theoretically. The geometry of the front axle is unlikely to be perfect at full lock so the front wheels will be fighting against each other and scrubbing slightly. Even if you know how much steering lock you have available, you'll only get an approximate answer.

How accurately do you need to get the answer. If you know the approximate turning circle you can judge the angle of the line from the outer front wheel to the center of the turning circle. If you can measure the distance along that line from the contact patch of the outer front wheel to the extreme corner of the bodywork then you will know the difference between the swept turning circle and the kerb-to-kerb turning circle. That's your best bet I would have thought - unless perhaps you can borrow the wagon and measure its actual turning circle ...

[towman]

Taking a wild guess, did the rear end of the truck hit smething? In which case a kerb to kerb turning circle will not suffice as the tail will initially swing out of that circle.

[towman]

The 0816 is a fairly rare beast. The 08 designates it as a 7.5 tonner and the 16 as 160hp. The cab,chassis and wheels will be exactly the same as an 0813.

Trucks come in a variety of wheelbases from the factory and it is also relatively simple to move the rear axle to accomodate a second hand body for example.

It is unlikely that there will be a data sheet for vehicle from Ford (the factory is long gone), but you may have some luck if you contact one of the larger dealers.

Sorry to duplicate lazyitis, but typing as I think!

Steve

[B19GRR]

Thanks guys, all good points.

Here's my problem. I need to show that this lorry could complete a 180degree manouvre in a 12m wide (kerb to kerb) space. Now I know it can because I saw it, unfortunately I don't have any data that can back this up at present.

Basically what happened is the box was being turned around on an A road making use of a layby on the opposite carriage so that the manouvre could be done in one go, an extended U turn in effect, road was 5m wide, the layby 7m deep. Unfortunately half way through the turn a motorcycle ended up crashing in to the rear passenger wheel and life has gone down hill from there. Here's in effect the sequence of events:

1: turn is started


2: as lorry reached this position motorcycle appeared and went in to rear wheel.


Police were called and a few passersby stopped.
This position can be confirmed as the rear axle was still in the left lane when the bike hit, with the lorry perpendicular to the carriage way.

3: lorry was moved forward slightly to allow vehicles to pass behind it and get on there way.


4: lorry was finally moved in to layby (facing the wrong way unfortunately).


At no stage was the lorry reversed to assist the manouvres.

So this is where it gets tricky, as to be able to complete these turns the lorry needs a turning circle of no more than 11m according to my scale drawings which just seems a bit mad. This is where not having exact details for the lorry is really causing a problem, as using the data I've got the minimum turning circle (kerb to kerb) I can get is 13.8m. We've now been able to establish that the fron axle is 94cm behind the front of the cab.

The owner is having a look in it's manual again though to see if there is any specs to help.

Is 11m even conceivable for a kerb to kerb turning circle for a lorry of this size? I figured my BMWs to be 9.6m, which matches up with my driving experience, and that's a fair bit smaller than the lorry!!

Cheers,
Rob

[towman]

Nasty. biker not too seriously injured I hope?

While I`m thinking.....

It is possible that the impact from the bike slid the rear axle in an "upward" (from your drawing) direction, thereby assisting the turning circle.

[B19GRR]

Luckily the biker walked away as he dropped his bike about 20m away and slid under the rear of the lorry as his bike embedded itself in the rear wheel.

The biker was on the right carriage way, travelling down the page so to speak. I kinda doubt the bike would've made any difference to the location of the lorry though, 7.5tons plus 0.5ton horse plus junk in back versus not very heavy bike?

Cheers,
Rob

[big dazza]

Is this data required as part of some sort of defence against legal proceedings regarding this accident?

[towman]

Quick question - width of road? You diagram and explaination are opposites!

[towman]

B19GRR said:

7.5tons plus 0.5ton horse plus junk in back versus not very heavy bike? Cheers, Rob

The lorry doesn`t weigh 7.5t. My guess would be 2 maybe 3 tonne on the rear axle. Remember Newtons law - every action has an equal and opposite reaction. The bike will definately have moved it - whether half an inch or half a yard is the question.

Incidently, forget the front overhang when calculating the turning circle - it is immaterial (unless there was a wall along the lay-by.

[towman]

Having read and re-read your posts, there is no way that teh truck could have completed the turn within the kerbs. The data you have for the 0813 is for 2.5cm extra wheelbase. That would not affect the turning circle by as much as 3 metres.

[B19GRR]

Yep, and there in lies the mystery as I saw it complete the manouvres without the lorry leaving the tarmac at any stage, it's a toughy isn't it

The owners have agreed to take it out tomorrow though and photograph it doing some turns which will hopefully clear some things up.

Cheers,
Rob

[t1grm]

Out of interest why is the fact that the truck can make a turn within the kerbs relevant to the accident? Surely if it couldn’t have made the turn within the kerbs it could have mounted the kerb or reversed. Either way it sounds like the bike still would have hit the truck whilst it was carrying out the first part of the manoeuvre and was across the road.

How fast was the bike going and was the manoeuvre being done near a bend? If the road was straight (as in your drawing) it seems a bit odd that a biker didn’t see a bloody great horsebox parked across the road.

Sorry, can’t help with the maths. I’m just being nosey about the accident

[tvrgit]

If you REALLY REALLY have to draw it to scale, get in touch with a consulting civil engineer who specialises in roads and car parks. There is an add-on to AutoCAD (called Autotrack) which can simulate turning circles for a very wide range of vehicles. You can also simulate non-standard vehicles if you know the wheelbase, steering lock, overhangs etc.

11m turning circle is very very small - most cars are about 30 feet (about 9.6 metres) with only small cars and taxis being able to turn tighter. You're talking about it turning in its own length - unless it has an amazing steering lock and is turning around a point below the differential, it doesn't seem likely.

[B19GRR]

The reason to get all hung up about whether the turn could be made between the curbs is the Police are insisting that it wouldn't be possible, it would have to be a 3 or 5 point turn. This is despite them being present when the lorry was moved fully in to the layby as in diagram 4.

As for the speed of the bike, well we're talking 11pm on a Sunday, clear country A road. Speed limit of 50mph and a 1000cc bike, read in to that what you will but I can guarantee it wasn't 50mph. The road was pretty straight from his direction, unfortunately the lorry is dark green, although with a large yellow strip along its side, so the headlamps and hazards would not be that visible at the time he arrived and the lorry was perpendicular to the road.

The driver is being prosecuted for dangerous driving (trial on Monday so we're slightly up against it!!). The DD charge is not because of the biker hitting the lorry but because of a slight hill and bend in the road in the direction the lorry was travelling - opposite to the motorcycles path. Strangely though no one else crashed in to the lorry, while it was still across the road and we were waiting for the police to arrive, from either direction.

It's debatable as to whether being able to prove the lorry was capable of completing the turn in one go will make any difference if the focus is really placed on the location of the manouvre. We shall see I guess.

Cheers,
Rob

[towman]

The only thing I can think of is that you may be mistaken in your belief that the truck was exactly broadside across the road.

[wolf1]

Take the truck out and video it completing a turn within the specified width. Even better if you can enlist a police officer to observe the manouver.

[towman]

Not much good I`m afraid. There is no evidence to show exactly where the turn commenced. i.e. truck could have been at least 0.3m from the kerb before a wheel was turned.

Playing devils advocate here btw.