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-   -   Memorable Moments (https://www.truckandbusforum.com/showthread.php?t=295)

Western SMT 16th October 2008 11:23

Memorable Moments
 
Driving a Transit van down the M6 during the day in the early 1970’s and it was raining heavily with road awash and very little traffic. Going round a gentle left hander and with van still looking as if it was being driven in a normal fashion it very slowly and neatly drifted from the inside lane to the middle lane and on to the outside lane by which time the road had straightened out and thankfully remained in that lane. Settling back down I didn’t think I was going that fast either and all that went through my head was - don’t brake and it was certainly a lesson in the power of water I’ve never forgotten.

billyboy 16th October 2008 12:33

Yes, Aquaplaning can be a problem at times. As you so rightly say...Dont Brake!

G-CPTN 16th October 2008 14:16

Simple 'mechanics' (physics):-
In order to deviate from travelling in a straight line at a constant speed, there has to be a 'force' available to push or pull the object (in this case the vehicle). This force has to be transmitted between the ground and the vehicle through the tyres (and the road surface - in this case covered in water). Simple tests show that wet tarmac or concrete has a lower grip than dry surfaces, and, of course the extreme of ice is obvious. (Though, interesting, hard, dry ice has a a higher grip than wet, melting ice which has a layer of water on the surface - this is the lowest grip surface of all.)
So, we have varying degrees of water, and the more water there is, the wetter the surface and the lower the grip.
To steer around a curve the tyres must have sufficient grip to transfer the necessary forces to the vehicle. Irrespective of aquaplaning (which is a condition similar to wet ice), the amount of water is directly proportional to the reduction in available grip, so be aware that when travelling at speed on wet roads, the ability to steer, brake and accelerate will be reduced.
Then there's the condition of oily-rubber (from tyres) that gets wet, vastly reducing the grip from dry rubber. Spillage of diesel fuel also has a devastating effect on grip.
Make sure that you have adequate room to 'drift' without hitting anything, especially when the roads are wet, particularly for the first time after a dry spell.

Part of my advanced driver-training involved constantly looking at surroundings for 'somewhere to have a crash' - meaning that you should be looking for an escape route should other vehicles enter your space or your intended manoeuvre become different to your intention.

(Another part was learning to drive two-thirds forwards and one-third behind you - ie always be aware of what is happening behind you - the instructor would cover the interior mirror (the lessons were in a car rather than a truck with external mirrors) and ask you to describe what traffic was following and whether they were catching up.)

Energumen 16th October 2008 20:42

Thank you G-CPTN, you see Billyboy, you just don't know your Ice from your Elbow,room.

Ha ha ha ha ha

billyboy 17th October 2008 09:32

Quite so Energmen.
G-CPTN, very well put. Especialy the comment about spilt Diesel. I have experienced that at a traffic island in the rain, about the same traction factor as wet ice as you so rightly say. had to use a bit of opposite lock and ease off the gas to regain traction. managed to exit at the right point though...LOL

Energumen 17th October 2008 17:14

I say, thank goodness that we do not have to drive some of the stuff, I did in 1969/70.

It was classed as mobile plant and as such did not require mot and was largely ignored by the police in any checks. Tyres that were through to their carcase made up a couple of those on any of them and cuts were turned to face each other on the twins.

One particular Thames Trader with a 55ft. Hydraulic platform mounted, had some real baldies on the front and I had the dreaded, forward motion, unimpeded by angled wheels, which were just aquaplaning, fortunately there was nothing right on the white line approaching me and the decelaration, quick straighten and re lock on, worked in time. (cor nearly wrote the wrong scenario there from a forward aquaplane on the same truck).


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