Maybe I can be of some use explaining, people seem to enjoy these threads, so...
Heavy Goods Vehicles Braking Systems 101.
A thread.
What you see there is two vehicles, each with a separate braking system.
Drivers need to understand how these brakes work so they don't kill themselves (or anyone else).
Heavy trucks brakes are pneumatic (worked by air) rather than hydraulic (worked by fluid) like in your car
The air lines have a long way to travel and need to operate reliably in this way and also exert huge forces, so air is a better medium but it makes for complex systems.
They also 'fail safe' so if air is removed from the system the brakes come on....
Which also means to take the brakes off, you need to apply air to the brake system.
With air supplied at sufficient pressure it will push back a huge spring inside the brake chambers allowing the parking brakes to be released.
Ok, boring, who cares?
When the driver is connecting a vehicle to a trailer, they will need to make sure the parking brakes are applied to both the trailer and the vehicle.
If the driver forgets one or the other, it removes a layer of safety that can mean the combination will roll away. Easily done.
If for example, a driver attempts to connect to a trailer and doesn't check if the park brake is applied. The brakes on the trailer will be ON.
Until the driver connects air to the trailer, at which point the brakes will be released. So the trailer is free to roll.
If the vehicle is not physically connected to the trailer at that point, via the kingpin and coupling, then there is nothing to stop it.
Perhaps the driver may also forgot to apply the parking brake in the vehicle... as well as failing to check the trailer... it happens
In which case the whole combination may roll away, and in this condition, the driver may even find themselves stood on the catwalk between vehicle and trailer as this begins to happen.
Don't ask me how I learned this one.
The hard way, it always is.
If this ever happens to you and you are stood here.
Immediately disconnect the 'emergency line', the red airline, this will dump the air from the chambers and the brakes will come on immediately.
Might save your life.
It's why I never recommend twisting the collar too far.
Coupling & uncoupling is one of the most effective ways to kill yourself if you get it wrong as a driver and it's something we are expected to carry out safely multiple times per shift.
But please tell me again how this is unskilled.
Dropped trailers like this happen every day
For clarity, I don't know the cause at Bristol Harbour.
This is not intended as direct analysis. It will be fully investigated and results will come out in time.
This is purely to illustrate something else you may not know about this most visible of invisible industries
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Well, if you listen to the old timers, they would tell you when trucks were made of wood, men were made of steel... or some other such cliche
But let's talk about the actual driving licence. Bet you have never been told this🧵
The driving licence in the UK wasn't introduced until 1935, and at that time there was no specific driving licence for HGVs.
In fact, in the early days of lorries, the hard part was finding anyone who could actually drive them with any mechanical sympathy, they were unrefined!
The sad truth of it, as it always tends to be: technology and resource is often driven by war.
It was in fact the First World War that led to the creation of a large driving force, people hastily trained in how to drive these rapidly advancing machines
Let's have a look at this, I am reminded so often that most people don't necessarily understand what they are looking at with this industry, so it might be quite interesting to dissect.
We call this a Bridge Strike, when you understand a bit more you can see why they happen 🧵
We can start with the lorry, UK registration, Belgian plates on the trailer, already dodgy yes?
No, the container belongs to ECS, a Belgian shipping company, in this case they also own the trailer, but they have nothing to do with the incident.
So why is the trailer here?
Well we voted for that, unfortunately. Brexit has seen a sharp decline in accompanied freight traffic in both directions, as there is a border where there wasn't before.
Trailers will now come here by themselves, and moved by a UK domestic haulier
How does this happen? Well it's far easier than you think.
Shall we start with how many times? Put "lorry hits bridge" into google and see what you get for 2023 alone.
Network rail who own a majority of the low road bridges in the UK estimate 5 bridges per day are struck by HGV
We, as 'professional drivers' are supposed to know the height of our vehicle at all times.
Brings a challenge of it's own. Because in the UK we only have to mark bridges in imperial. But we often measure vehicles, particularly trailers, in metric.
So you have to do the maths
But you also have to consider the coupling height, as most of us will be dealing with a tractor unit and semi trailer, which have two different heights to worry about
And just to make it more complicated. The coupling height marked here is often different between trucks
I realise talking about not drinking is about as popular in the UK as a fart in a lift, particularly at this time of year
However, it is a very popular time to consider it, for obvious reasons, so here goes: 5 years ago today I stopped drinking
Here are some things I learned
Before I say anything else. It's a very difficult thing to discuss with people, still, even though it shouldn't really be.
You can see evidence of peoples reactions to such topics all over twitter today.
Normal. If you decide to stop you WILL bump up against this stuff.
Also, if you don't want to read anything else from me but would like to know where to start. Highly recommend The Unexpected Joy of Being Sober by @cathgraywrites which is 99p on Kindle today.
Probably the kindest, relatable and compassionate book I have read around giving up
You don't 'tempt' ex-offenders by offering the very worst of jobs available and expect them to bite your arm off, because it's somehow suddenly more tempting than a life of crime.
What colour is the sky on the planet these MPs are from? They are so detached it is beyond farce
Myth buster number 2:
Foreign labour is not cheap. Our European friends were paid the same rates as our UK drivers.
They just might be (were) willing to do the rough job, dirty work and long hours...
The rough, dirty, long hours that the UK transport industry demands.