Carryfast:
Rjan:
Carryfast:
As I said braking from high speed in the middle of the bend certainly will usually result in a lateral off either in the form of under steer,over steer,or even both ends at once or with a high c of g and/or one of those weird artic things more likely to trip itself up and throw itself over on its side unless you can take off enough lock to straighten it up which is more or less the correct action described by Juddian.I don’t see how a braking application can apply an adverse lateral force to a trailer. The lateral force which induces the rollover is either a centrifugal force induced by the turn, or a change in camber, or both.
I agree straightening the vehicle up or steering back into the direction of the roll will always be recommended if possible in addition to braking.
But if you’ve steamed onto the inside of a roundabout, for example, you might not be able to ease the steering without knocking someone out of the way or putting yourself on a collision course with something. Or if you’ve mounted a trief kerb, it’s quite likely to be because someone has hemmed you in.
So I would never say “don’t brake”, because you will buy yourself extra moments to think, and by going slower you ease any lateral forces being imposed - by scrubbing off speed as fast as you can, you may be able to proceed on your pre-planned course, bring things back within safe margins, and render any other tactic irrelevant.
As for the vid as I said ‘enough’ power and the right weight distribution to create mild over steer over roll.While a ‘bus’ might just about manage the weight distribution side but just doesn’t fit the definition of enough power unless you can put a 500 hp + motor in it.While notice the driver rightly applied power in the bend he didn’t dare brake.On that note you won’t make a fire truck test driver.
But without considering whether that is right or wrong, we’re simply not talking about testing a fire truck on a track (a rigid vehicle specially designed to be driven like the clappers and stay upright), where an experienced test driver is mentally prepared and is intentionally taking things to the limit in a safe environment.
We’re talking about what to do in the situation where a driver has made a grave error through inattention or radical misjudgement (or unexpected behaviour of other traffic), and suddenly realises he’s about to roll the vehicle and has one last throw of the dice to avoid catastrophe. I say hit the brakes all the way.
Firstly the fire truck vid was only meant as an example as to how applying power can and does work.But obviously not in the case of the average commercial vehicle which was the point.
However not braking after turning into a bend and especially if the entry has been over cooked generally applies regardless.While in the case of an artic trailer it’s effectively just a big rigid vehicle steered by the tractor unit’s drive axle at the end of the day.But with the downside that the more lock that’s applied the less support it has at whichever corner of the front end is on the outside of the bend.At which point the handling characteristics become like a three wheeler car but on a much bigger scale and let alone if it’s also combined with a high c of g.Which just magnifies the effect I described of the forward momentum being turned into lateral force most likely roll in this case.Because 1 the thing just doesn’t want to go where the steering wheels are pointing and 2 that lateral force conversion obviously takes place and is applied before you can shed the speed with the brakes and 3 an artic doesn’t have the same amount of support at it’s front end when it’s turning with the drive axle at an angle to the trailer as a rigid does.While c of g is king regardless in that a high c of g will just as happily throw a rigid on its side as an artic at virtually any speed in which case trying to ease off the steering is better than panic braking in the middle of a bend.In addition to making sure not to go from one lock to the other without pausing at the straight ahead position.
Have you more experience of artics or 3-wheelers?