Endurance Braking.
Posted: Sat May 23, 2009 11:26 am
On a recent assessment drive I was criticized for making a gear change before a number of hazards. The scenario is that I am driving a coach along a flat piece of road in fifth gear at the 40mph speed limit, I have spotted in the mid-ground a short slope with a 30mph limit change, some islands and other features of small town centre including parked vehicles significantly reducing the roads width. I had decided that to make good safe progress, I would proceed at 40mph for the first half of the slope which could be maintained by selecting fourth gear which is also required when I enter the 30mph limit which I would reduce to using light use of the service brake whilst entering the congested town centre with a flexible gear already engaged. I selected fourth before the hill engaging with the engine revs matched for a smooth gear change which prevents the associated clutch were encountered with a brake-gear overlap whilst giving me less to do entering the series of hazards in the coaches path.
I was asked if I meant to change to the lower gear when I did, I responded with yes and brief outline of the description above. The response was "Just use the exhaust brake!".
Re living the scenario based on my memory I conclude that the exhaust brake would have likely held the coaches speed at 40mph during the short slope, I would have then used the service brake lightly to reduce to 30mph on the approach to the limit change but then see no alternative but to overlap the gear change with braking due to a slight gradient as the remainder of the hill flattens out at exactly the same point where the other hazards begin. I believe that this approach would have caused more mechanical wear, required a great deal more physical control use in a short space of time and giving me less control over developing situations.
To back up the view of my assessor who is one of the coach companies mechanics, the saying goes 'brakes to slow gears to go'. I used the gears initially to maintain a speed which shortly afterward assisted the brakes in speed reduction.
To further analyze some of my general driving practices, I always avoid brake-gear overlap when possible due to my Mini having a distorted clutch plate requiring a double-de-clutch and perfectly matched engine speed for a lower gear to engage and where there is no alternative to brake gear overlap I nudge the accelerator with the side of my right shoe.
In the world of PCV driving the only retarders I have used are the automatic type as fitted to automatic service buses with the best one being fitted to most Mercedes Benz O405's, these engage with the service brake at a light setting.
I would likely consider using an endurance brake for use on long descents, or in conjunction with a lower gear in slippery conditions, but even on a long descent I would likely use the endurance brake in conjunction with a flexible gear.
So the question is, with my first scenario what should I have done better?
I was asked if I meant to change to the lower gear when I did, I responded with yes and brief outline of the description above. The response was "Just use the exhaust brake!".
Re living the scenario based on my memory I conclude that the exhaust brake would have likely held the coaches speed at 40mph during the short slope, I would have then used the service brake lightly to reduce to 30mph on the approach to the limit change but then see no alternative but to overlap the gear change with braking due to a slight gradient as the remainder of the hill flattens out at exactly the same point where the other hazards begin. I believe that this approach would have caused more mechanical wear, required a great deal more physical control use in a short space of time and giving me less control over developing situations.
To back up the view of my assessor who is one of the coach companies mechanics, the saying goes 'brakes to slow gears to go'. I used the gears initially to maintain a speed which shortly afterward assisted the brakes in speed reduction.
To further analyze some of my general driving practices, I always avoid brake-gear overlap when possible due to my Mini having a distorted clutch plate requiring a double-de-clutch and perfectly matched engine speed for a lower gear to engage and where there is no alternative to brake gear overlap I nudge the accelerator with the side of my right shoe.
In the world of PCV driving the only retarders I have used are the automatic type as fitted to automatic service buses with the best one being fitted to most Mercedes Benz O405's, these engage with the service brake at a light setting.
I would likely consider using an endurance brake for use on long descents, or in conjunction with a lower gear in slippery conditions, but even on a long descent I would likely use the endurance brake in conjunction with a flexible gear.
So the question is, with my first scenario what should I have done better?