Braking

[Mr Cholmondeley-Warner]

Pruned (I did ask you to get back on topic earlier). By all means start a bunfight about chariots in General Chat or somewhere. This is Christian's braking thread.

[R_U_LOCAL]

OK, can we get back on topic now, please!

Reg, can you sort of describe in a word or two, your phases, pretty please?

Ok, let's break the action of braking to a stop down into it's constituant parts and see what the subsequent pile of bits and bobs looks like.

The initial phase disassembles like this:

1. Scanning and taking in information allows the driver to see a hazard up ahead and start the planning process.
2. The driver forms the plan that they will stop at the hazard.
3. The driver releases pressure from the accelerator and "finds" the brake pedal with their right foor.
4. The driver applies a very slight pressure to the brake pedal - just enough to take any "slack" up and push the pads up to the discs.
5. The car will not be slowing at this stage, but just maintaining a constant speed, and the driver will then start to gently squeeze the pedal, feeling the first hints of resistance in the system, friction with the discs and slowing of the car.

On to the middle phase:

6. Continuing to scan whilst starting the braking process, the driver is comstantly making assessments and re-assessments about the required rate of deceleration on which they will then base their decisions for the next few phases.
7. Increasing the pressure on the pedal, the driver also takes information from the sole of their foot and their hands on the wheel which allows them to monitor how the car is reacting to the application of the brakes.
8. At this point, the driver should be approaching the firmest point of their braking, losing speed at the fastest rate and continuing to re-assess the required rate of deceleration and the feedback from the controls.
9. During this maximum braking phase, the driver will make small adjustments to the amount of pressure on the brake pedal - very subtle adjustments which are usually un-noticable to passengers if performed correctly but which will prevent either over-run at the hazard or stopping short.
10. Back to the mental aspect, the driver continues to scan and plan and makes a decision on when to start reducing the pressure on the brake pedal.

And the final phase:

11. The driver starts to release pressure on the pedal, feathering back on the brake pedal to reduce the rate of deceleration and bringing the speed down to just a few MPH.
12. As the vehicle comes to a stop, the driver releases the pressure on the brake pedal until the brakes are almost completely off, with just enough friction between the discs and the pads to roll the car to a smooth stop.
13. Once the car has stopped, the driver then re-applies some brake pressure to ensure it doesn't roll either backwatds or forwards whilst deciding whether to apply the handbrake or take first gear to go.

So there you go, Reg's 13 phase braking system.

Much simpler to teach if you stick with the three phases though!

[Mr Cholmondeley-Warner]

Ah, or to put it another way:



You've described 13 points on the curve, but there could be any number (apart from nos. 1 and 2, which are not associated with the physical action at all, and no. 13, which is, if you like, a second application of the brakes).

[Strangely Brown]

Or...

rub, condense, release.

[TheInsanity1234]

Or even more simpler:

slow the f*ck down or y'all gon' hit dat.

[Horse]

5. It will slow, otherwise you have perpetual motion

7. More than that, elbows / seat belt against chest / friction on seat, etc

[jcochrane]

What works for me is a four stage system for country driving.

Transition...light pressure to engage the pads.
Firm up braking...increasing pressure to a point that is often more than required.
(These two elements done in the early phase (usually in the first third or less) of braking and before mid distance.)

Manage the rate of speed reduction....easing pressure off as the car slows to achieve a constant rate of speed reduction ending with...
Trnsition off Braking a featherlight pressure as the car comes to a stop or completion of braking leading to no pressure and back to accelerator. As would be done in threshold braking)

For town driving however I rarely do more than lightly brush the brakes to reduce speed or stop

[waremark]

I enjoyed the 13 point plan.

What I am finding difficult is how to decide when to start braking and how firmly to brake for a given hazard. The later you leave it to start braking the more you know about the hazard and therefore how much speed you need to lose. But the later you leave it to start braking the more firmly you may have to brake. I think the firmness of the braking should be consistent with the overall pace of the drive.

As a side issue, being able to stop in the distance .... begs the question of how hard you would have to brake for what probability of obstruction, and how much you want to have in reserve. And whether you regularly practice braking on a curve so you know what the relevant distance looks like!

[IcedKiwi]

As a side issue, being able to stop in the distance .... begs the question of how hard you would have to brake for what probability of obstruction, and how much you want to have in reserve. And whether you regularly practice braking on a curve so you know what the relevant distance looks like!

That's what I struggle with - Do I know I could stop within that distance? The other thing is limit points - Once it starts running and you've "found" the tightness of the curve, you need to then have some mental database of what speed is appropriate for that radius and whether it's OK to come off the brakes.

[Horse]

The later you leave it to start braking the more you know about the hazard and therefore how much speed you need to lose.

Now let's add in an extra 'variable': slowing earlier allows you more time to assess the situation

So perhaps there's a two-stage/option assessment/decision going on? From further back, and depending on your intended rate of progress, you decide whether to happily barrel up to the hazard or, perhaps, you decide that there isn't enough information to make a decision, so ease off earlier to allow more time for the necessary assessment.

As a side issue, being able to stop in the distance .... begs the question of how hard you would have to brake for what probability of obstruction, and how much you want to have in reserve. And whether you regularly practice braking on a curve so you know what the relevant distance looks like!

If it's an obstruction, then that's a fairly absolute 'choice' to make . . . Since no-one could ever accurately predict stopping to within a gnat's, it's essential to maintain some reserve.

And, of course, if approaching a blind corner then you're probably better off assuming that there is an worst case obstruction around every bend . . .

At this point, Mr CW will be yelling "Surprise Horizon!" at the screen, because the relevant distance around a curve may well not be the limit point.