Engine Braking

[combover]

GreenV8S said:

I find that there are often situations where a limit reduction cannot be seen soon enough to slow down to the new limit just using engine braking. Similarly when approaching junctions it would usually be impractical to slow down sufficiently using engine braking alone. As has been said before, the goal is to avoid unecessary braking. Perhaps a better way to think of it is to avoid pointless application of power. Why keep the power on, when you could shut off and start coasting down rather than keep going and then have to brake? But moderation in all things, coasting everywhere is neither practical nor desirable.

Excellent, a post which sums up my thinking in one go.

[gridgway]

GreenV8S said:

I find that there are often situations where a limit reduction cannot be seen soon enough to slow down to the new limit just using engine braking. Similarly when approaching junctions it would usually be impractical to slow down sufficiently using engine braking alone. As has been said before, the goal is to avoid unecessary braking. Perhaps a better way to think of it is to avoid pointless application of power. Why keep the power on, when you could shut off and start coasting down rather than keep going and then have to brake? But moderation in all things, coasting everywhere is neither practical nor desirable.

Yep, well said. It seems to come down to a judgement call and choices as to how you want to drive.

However, here's a thought...(oh no, says Sally when she just gave a great big hint that I had done the subject to death hehehe)...

You could view the method of speed reduction as irrelevant. Why should the engine be better or more appropriate than the brakes for example? It's not hugely logical to conclude that engine braking is good predominantly over and above the brakes. You could conclude in a 2 wheel drive car that as engine braking happens only with the driven wheels rather than on all 4, it's actually undesirable. The fact that timing the braking using the engine is clever doesnt make it good per se.

You could conclude that an approach which required a different skill was better (if skill were the determinant). So a different skill would be to decelerate (ha) to use (say) a maximum of 80% of the available tyre grip at any one time with a certain application and er de-application profile (IYSWIM) to make it feel really really smooth.

That looks like a good skill to me, it supports a good make-progress style. So what does it have against it compared with the "IAM Method" (not being derogatory in any way, just musing)? Well the IAM method should use less fuel and less brake pads, but I'm not too worried about that. The Ridgpoo (hehehe) method requires a greater level of skill, doesn't hold up people behind and is more satisfying for the driver.

Course it's all a load of old twaddle, but fun!

Graham

[GreenV8S]

[redacted]

[gridgway]

GreenV8S said:

In normal driving though, smooth comfortable and safe progress with minimal wear and tear is more important.

Indeed, nothing smooth and uncomfortable in my new system, if there is then the skill hasn't been learnt yet. Wear and tear in itself is spurious in my system as it represents just a cost to be managed, the increased tyre and brake *cost* is negligable in comparison with fuel costs and depreciation.

I am warming to my new system it has the benefit of being very flexible for different uses and it's quite measurable. So with gps and accelerometer based data logging the braking profile and percentage grip are easily shown. It can be extended to acceleration as well as deceleration, thus there could be well defined stages of Gridgway Advanced Driving Skills (GADS) for everything from novices to super-duper drivers. It can be used on track as well!

I'll get me coat!

Graham

PS anyone want to hear my proposition as to why using the handbrake ratchet is safer and thus more advanced than the silent method? No I thought maybe not :-))

[GreenV8S]

I hope you extend the GADS system to steering as well as acceleration/braking. (Have you noticed how many drivers seem to be continually correcting the steering and end up gently weaving down the road all the time?)

[renny]

GreenV8S said:

I find that there are often situations where a limit reduction cannot be seen soon enough to slow down to the new limit just using engine braking. Similarly when approaching junctions it would usually be impractical to slow down sufficiently using engine braking alone. As has been said before, the goal is to avoid unecessary braking. Perhaps a better way to think of it is to avoid pointless application of power. Why keep the power on, when you could shut off and start coasting down rather than keep going and then have to brake? But moderation in all things, coasting everywhere is neither practical nor desirable.

I agree with you on this. Consideration should also be given to the fact it may be useful to inform other road users that you are slowing down. This is usually acheived by displaying the brake lights, although the use of hand signals could also be considered (e.g. on approach to a pedestrian crossing, although in practice hand signals just confuse folks).

Another point to ponder is moving on from driving cars and the discussions on engine braking destabilsing the vehicle, to driving LGVs and coaches where considerable engine braking can be acheived using exhaust brakes and retarders which only affect the drive axle (out of 6) at gross weights of 40tonnes plus. Many of these systems are so effctive that the manufacturers have linked the use of these to illumination of the brake lights, and drivers have to be very aware in slippery conditions that the retardation on one axle can cause instability.

[gridgway]

GreenV8S said:

I hope you extend the GADS system to steering as well as acceleration/braking. (Have you noticed how many drivers seem to be continually correcting the steering and end up gently weaving down the road all the time?)

yes indeed, and my data logger can be used to test the skill as well!!

Graham