Large Automatic Gearbox - Procedures

MiniClubmanEstate

I found the information on the Kent Rospa site regarding the use of an automatic car useful as I have never been formally trained in the use of automatic gear boxes. On my First Edinburgh assessment drive I got a shot of a Wright Access which has a Scania engine and automatic gear box, this was the first time I had driven an automatic as my PCV training was done in a manual coach. The instructor told me quickly how to use it, we never took the bus out of gear until we arrived back at the depot where I was interviewed. One thing which I now look back on is that when I stopped, even at a bus stop I applied the air operated handbrake but left the gear buttons alone. When performing the bus stop exercise I pulled up, applied the handbrake, released the foot brake and opened the doors. I now know that on the PCV driving test the procedure is to stop, apply the handbrake, select neutral, release the foot brake, cancel the indicator and then open the doors. I just wonder if all this was really necessary given that the driving instructor gave me a debrief, my quick procedure was not mentioned and he stated that my assessment drive is the best he's seen in a long time.

On a large automatic vehicle with an air operated handbrake is it necessary to select 'N' if I want to release the foot brake?

I have been looking for ways to work more efficiently and believe that my procedure works:
1. handbrake
2. release foot brake
3. open doors
4. deal with passengers
5. check door area is cleat and then close
6. apply foot brake
7. release handbrake
8. make full observations and proceed when safe

Standard widely used (not by me) version:
1. with the bus slowed to 10 MPH open doors
2. deal with passengers
3. GO GO GO!!!
I do not believe that this version is particularly safe, I have a long list of reasons which I will not go into.

This could be a possible version to maximize efficiency without compromising on safety once stationary:
1. Doors open button - They take a few seconds
2. Handbrake - this will be on before the doors have opened enough for passengers to step on or off the bus, the foot brake will not be released.
3. deal with passengers
4. Check door area and near-side mirror, press doors close button if safe
5. release handbrake - remember the foot brake is still applied
6. Check the near-side with the doors now completely closed whilst taking the opportunity to check the tail is clear to swing using the near-side mirror
7. continue with observations and proceed when safe.
The above procedure is considerably quicker whilst I also believe safe. The only thing that can go wrong with the procedure is a slip from the foot brake, the vehicle is secured with the handbrake and I have simulated this with an out of service bus to see if the floor would move slightly and it does not. I would appreciate any feed back and opinions on this procedure.

As for driving automatic buses I mostly use 'D' with the kick-down being an option to start pressing on when the road is clearing although it doesn't work on some buses. I've driven an old Mercedes single-decker which has a brilliantly responsive engine and gear box and with kick-down, it's my favorite bus to drive. At the other end of the scale are the legendary Denis Darts. The Denis Darts have a lever type gear selector which I use quite often as the kick-down often does not give the lower gear for long enough. Often the only way to make any amount of progress in some Denis Darts is to just use the selector always and rev the small engine, in this fashion some are much quicker than if used in 'D', it can take 40 seconds to make 0 - 30 in some of them in 'D'. To get the Dart moving I usually lock into '2' if I am negotiating a junction so that I can keep both hands on the steering wheel and being ready for the acceleration phase, I will use '1' if I'm going straight ahead to make maximum progress.

I would be interested to know what others, particularly the large vehicle squad what you think of my ways of working, I'm eager to learn as I have little experience and would like some idea of how my driving is progressing or deteriorating.
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Andrew: PCV, IAM Car
Smoky - Pronounced as Smokey, a unique little Mini.

Terry Williams · Joined: 27 Feb 2007 Posts: 5 Location: Bedfordshire

Andrew

The method I have used for years generally is your modified version-as the vehicle comes to a standstill press doors open button, immediately followed by applying the handbrake and then release footbrake.

As you say it takes a few seconds for the doors to fully open and with this method the hand brake is fully on well before the doors are open.

Opening doors before the bus has stopped, even at 10mph or less, is wrong and would make you culpable if a passenger was hurt.

With modern Dennis Darts the open button can be reached with the forefinger with the hand already on the handbrake in its off position.

I see no point in holding the footbrake throughout the stop,re- applying it just before releasing the handbrake.

I leave the selector in drive throughout until I leave the cab except for a lengthty layover and have found little to be gained by holding lower gears.

I hope this helps,

Kind regards

Terry
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TJW

Renny · Joined: 27 Apr 2006 Posts: 366 Location: Fife, Scotland

I have no problem with what you are suggesting as your alternative method. The park brake operates on the same system as the footbrake, both actuate the same parts, the difference is that with the park brake, a spring in the air brake unit applies the force, whereas with the footbrake, it is the air pressure acting on a diaphragm that applies the force. It might be that the park brake only works on the rear axle, but more likely it operates on both.

It might be that when you move off, releasing the park brake slowly, without the footbrake being applied gives you a smooth enough take off, although this may depend on the location of the brake lever. Not relying on the footbrake alone is sensible for the reasons you mentioned.

As for the gearbox, I have very little experience of driving these "simple" big autos. Some of our refuse trucks have Allison automatic transmissions with vey few gears compared to the automated manual boxes found in large haulage trucks that I'm more familiar with. With autos, I tend to use "D" unless I want to hold a gear either to prevent an upshift in the middle of a hazard, or when I want to hold the revs/power for tackling a hill that the gearbox cannot "see" ahead.
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Renny Thomson

MM0KOZ
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John C · Joined: 13 Jan 2006 Posts: 29 Location: Kent

Hi, interesting to see your post about big auto's. I love them.
I am pleased that you found the info on auto boxes from theKent RoSPA site useful. It was written for car autos which are not as heavy duty and not designed to take heavy loads. The parking brakes on cars are, in my opinion, not as good as they could be so popping the box in to "N" helps to prevent any tendancy to creep. Also the oil coolers on car auto's (if fitted) are not as good as they could be. So popping it into "N " on a long stop can prevent overheating which it could do if left in D for long periods.
On buses, trucks etc the auto boxes are a lot better made and the oil coolers are designed to match. The air parking brakes will hold the vehicle quite easily with the box still in D and the oil cooler will cope with any heat generated quit easily.
So what you are doing is fine. Use the technique that best suits you.

rodericksdad · Joined: 17 Apr 2006 Posts: 70 Location: Lincolnshire

On the MAN,s that we run once you have stopped and the parkbrake is applied or the vehicle is held for more than a second or two the drive is disconected,as soon as you start to lift off of the footbrake or parkbrake is started to be released the drive is reinstated back it seems to work fairly well at the moment but they are only just over a year old.

"With modern Dennis Darts the open button can be reached with the forefinger with the hand already on the handbrake in its off position.

Wow,wish the same body/coach builder had done ours like that,most of ours seems to have had a team set up to specifically try and put buttons and warning lights where the driver has to take his eyes off the road to look at w/lights and the buttons are stategiclly placed so you have to be double jointed and see round corners to get to them. Laughing

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Best regards,Clive.