Not sure if modern trucks have a different system but they used to have exhaust brakes that would use the engine to assist with slowing the truck on a decent.

No, brakes won't automatically be applied in an overrun situation, except where cruise control is in use any automatic retarder is engaged and the overrun speed set, if the driver touches the brakes themselves cruise will be cancelled.

Cruise often has a driver set overspeed allowance (it might have a pre set allowance which might be +6kph), typically 2kph over set cruise speed isthe lowest the driver can set it for auto retardation and if the retarder isn;t enough then auto braking will also be triggered to keep speed under control...ie if cruise is set to 55kph and +2 is set for overspeed then the truck will invariably be travelling at a (vehicle not driver) controlled 57kph until the downhill levels out again.

Here comes the fun part, like with cars they've made truck dashboard and menus so complicated that it can literally take months of regularly driving one make and type of vehicle to fully familiarise yourself with every idoisyncracy, and all makes are different.

Its taken me some 120k kms on the the new vehicle i was issued with last year to learn all of its foibles, and the latest otherwise identical ones that have turned up are different again, how an irregular driver using a different vehicle every day is supposed to work all this gadgetry out no one has quite explained.

if one could be bothered to study the drivers manual deeply enough to know all the shift would be over before you had left the yard....at night things are far far worse, some trucks are preusumably fitted with switches via the confetti method, ie throw a tray of switches in the air and where they land they get fitted, i'm joking here but seriously some are that bad.

Anyone looked recently at the average lorry driver, he and its mostly he's are over 55 and heading rapidly to retirement age, did anyone explain to truck designers that drivers are not all 18 year olds having grown up with electronic toys gadgets and computers, no obviously not.

Yes the UK limit is 60mph but seeing as we never left the EU :) we still have to abide by EU regs (and almost every truck is made in europe anyway) , hence the digi tacho will start throwing recordable overspeed warnings at around 3kph over limter speed if continual over several hundred metres.

As for checking speed, remember the truck speedo will be calibrated very accurately assuming new tyre depth, if the tyres are worn a calculation for wear will be made so putting the vehicle in for calibration on tyres down to 4mm from 20odd won't always result as one might think, a car speedo reading of 62 is probably more like a true 57..

Edited by gordonbennet on 24/07/2025 at 18:40

Mainly because drivers are reluctant to drive in lane 1 at 70 mph because they consider it the "slow" lane. If more did move over it would be easier to overtake in the outer lanes.

Which is why I (and seemingly many others) choose to drive at or near the NSL in lane 1, because it's usually the least used.

With so many speed cameras these days, I increasingly find that normal cars have these snails pace races overtaking each other at +1mph because one car’s 70mph is calibrated differently to another.

Yes, but does that really matter? Lane hoggers are a lesser evil than lane hoppers. Drivers who condtantly cut in and pull out probably slow the traffic down more than someone sitting in lane 2 doing 69 mph. This is because they often cause other drivers to brake when they change lanes abruptly.

I disagree. Whilst they are certainly a menace, people changing lanes frequently are normally encouraged to do so by others sitting in the middle lane forcing them to find a way around.