Steering wheels in locomotive cabs ? (Glacier Express)

[Lost property]

Watched a programme last night about the "Glacier Express " and there, in the centre of the console, was a steering wheel. I'm certain, could be wrong I admit, about the location, I've seen similar on Norwegian locomotives and elsewhere.

So the questions are, why please?....and why don't UK locomotives have them ?....I'm just genuinely intrigued as to why.

 

[DanielB]

It's not a steering wheel, but better compared gas pedal in a car: this wheel is used by the driver to control the power delivered by the electric engines.

Those wheels are found in mostly older electric locomotives (and in the Netherlands also the driving trailers that used to work with the 16/17/1800 locomotives have them). No idea why UK locomotives don't have them, probably just because a different technology was chosen as there are multiple examples in Europe of stock having a similar age but no wheel.

Source for the above post was this article on the Dutch version of Wikipedia, couldn't find an English version that quickly.

 

[ac6000cw]

No, they are not steering wheels - they are usually power controls (instead of using a handle or lever) on electric locos. Sometimes they control a handbrake e.g. the handbrake wheel on the driving desk of 1950's BR Mk1 DMUs.

I think on early electric locos the power control wheel directly controlled power switches etc. so needed to be a reasonably large diameter to get enough leverage.

 

[Roast Veg]

I think on early electric locos the power control wheel directly controlled power switches etc. so needed to be a reasonably large diameter to get enough leverage.

Yes, precisely. Early BR electric locos didn't use big wheels to move the notches, instead using a motor(?) notch controller.

 

[Trackman]

No, they are not steering wheels - they are usually power controls (instead of using a handle or lever) on electric locos. Sometimes they control a handbrake e.g. the handbrake wheel on the driving desk of 1950's BR Mk1 DMUs.

Class 28 springs to mind with a wheel for the power controller.

 

[Fragezeichnen]

Yes, precisely. Early BR electric locos didn't use big wheels to move the notches, instead using a motor(?) notch controller.

It's still the same system in essence. The large wheel cab controller, though heavy duty compared to modern locomotives, isn't directly selecting the notch in the high voltage circuitry, it just commands a motor to move to a certain position.

The alternative as used in the UK, and also in Germany is to just let driver say 'more power' 'less power'. It doesn't make much difference in the end, you are limited by the speed of the motor.

Many permutations are possible. Some German locomotives had a large wheel controller but with only 4 positions for Up/Down controller. The BR103 had both.

 

[Flying Snail]

The alternative as used in the UK, and also in Germany is to just let driver say 'more power'

If Jeremy Clarkson had been a train driver maybe.

 

[contrex]

I've seen in-cab videos of SNCF locos where the driver operates the wheel by moving it about 30 degrees or so clockwise to notch up and then letting it go back. You can usually hear a contactor click as that happens. I thought of it as being another way to move a vertical shaft. You could just have a single spoke of the wheel with a knob on the end.

As an example, you can see this at about 15:57 in a CC 72000 diesel loco (CC 72067) in this La Vie du Rail video on Youtube. First the driver does all the preliminary checks. Quite interesting. I loved these machines. I think you can see, from the cab design, why French drivers didn't like the class 92s from a crash protection point of view.

 

[ac6000cw]

I've seen in-cab videos of SNCF locos where the driver operates the wheel by moving it about 30 degrees or so clockwise to notch up and then letting it go back. You can see a contactor click as that happens. I though of it as being another way to move a vertical shaft. You could just have a single spoke of the wheel with a knob on the end.

Exactly.

A lot of this sort of thing is just crew familiarity/established practice for that railway system etc. rather than any one method being better than another.

As an example, US diesel locos for many years had the main control levers (moving horizontally) on a 'control stand' to the left of the driver. Then in the 1990s (I think) there was a move to a driving desk control layout with fore-and-aft vertical levers. Eventually the crew feedback was that they didn't like that, so new locos reverted to a modern version of the old 'control stand' layout.

 

[Lost property]

Thank you for the replies. I used "steering wheel ", on reflection I should have included " " in my original post, because that was the most obvious comparison. I am / was familiar with the wheel as a handbrake on the DMU's so ruled out those shown in this capacity.

I understand why a power lever is used to control power, the ergonomics alone being obvious. That said, I had a very enjoyable Diesel driving day on the ELR driving a Class 37, sorry if I've got the Class wrong and was intrigued to see an ammeter in the centre of the dials, not the speedometer as I'd expected....then I was shown the rheostat in the engine compartment !....which explained the power lag.

 

[XAM2175]

I understand why a power lever is used to control power, the ergonomics alone being obvious. That said, I had a very enjoyable Diesel driving day on the ELR driving a Class 37, sorry if I've got the Class wrong and was intrigued to see an ammeter in the centre of the dials, not the speedometer as I'd expected....then I was shown the rheostat in the engine compartment !....which explained the power lag.

For comparison, this is the driver's desk in a DB E 10 (later Class 110) loco, built in the early '60s:

(from https://commons.wikimedia.org/wiki/File:2013-09-15_11-33-17_E_10.jpg)

In this case the control wheel has a distinct position for each of the 28 power notches, rather using the notch-up/notch-down system other uses have mentioned above.

Directly in front of the control wheel are four ammeters - one for each traction motor - and to the right of them is first the speedometer and second the notch-selected indicator.

 

[MarcVD]

Basically, it all depends which kind of loco you're driving.

The loco like the DB E10 shown above is fed by alternate current. A transformer with several notches on the secondary coil is used to input variable voltage to the motors. The loco can remain on any notch that the driver wants for any length of time. Thus such a wheel allowing manual selection of notches makes sense.

On locos using direct current, things are less simple. You cannot use a transformer. So instead a variable resistance is used. This resistance produces a lot of heat, which is energy lost in the atmosphere, and could cause damage if used for too long. Such locos therefore use an automatic mechanism that passes through the notches in a controlled fashion, leaving the driver to use only a few stable positions : different couplings of the motors and always with the rheostat fully eliminated. It was not always like that, though. On early DC locs, the driver had manual control of the rheostat notches and had to monitor the Am-meters to know when he could switch from one notch to the next. It required some skill...

Modern locos using three phase motors and inverters are of course yet a totally different affair. Speed is fixed not anymore by applied voltage but by frequency. On such locs the driver can have a total and continous control of the frequency applied to the motors, the notion of notch totally disappears, and the control us usually done by a simple joystick.

This was my minute of very simplified electrical traction engineering.

 

[hexagon789]

Assuming the loco in question was a GE 4/4 III, the control wheel actually has different functions.

From centre, moving anticlockwise gives rheostatic braking, clockwise is power.

There are 3 power modes:

Shunt - where the wheel controls tractive effort

Speed control - where the wheel controls the set speed and power is applied automatically to maintain this

Speed control half-power - as above but tractive effort is restricted to 50% of maximum and continuous ratings (used for light loads and running light engine).

It might be noticed that there are numbered markings round the wheel, on the power side these are from 0 to 10. 0 is off, 4 = 40km/h, 10 = 100km/h etc; there is a half-notch (5km/h) between each numbered notch.

 

[Bakerloo]

It's common on quite a few trains in Poland

 

[duesselmartin]

Back to the DB E10. Has it got AC motors or is the current converted?

Thanks
Martin

 

[MarcVD]

Back to the DB E10. Has it got AC motors or is the current converted?

Thanks
Martin

As far as I know, AC motors (which are just plain serial motors but with AC power supply) and a transformer with variable output voltage as I explained in my post above...

 

[Richard Scott]

Back to the DB E10. Has it got AC motors or is the current converted?

Thanks
Martin

They're DC motors but run using AC supply, I believe, hence 16 2/3 Hz as it limits arcing on brushes on the commutators. They rotate in one direction on AC as current in field and armature change direction at same time. Was due to technology on rectifiers not being sufficient for rail traction at time of initial electrification. Class 151s were thyristor controlled, all classes built before that ran as described above, I understand. Happy to be corrected.

 

[317666]

They're DC motors but run using AC supply, I believe, hence 16 2/3 Hz as it limits arcing on brushes on the commutators. They rotate in one direction on AC as current in field and armature change direction at same time. Was due to technology on rectifiers not being sufficient for rail traction at time of initial electrification. Class 151s were thyristor controlled, all classes built before that ran as described above, I understand. Happy to be corrected.

The last few batches of 110/140/150 used the same thyristor control as the 151s. The 181s were also thyristor controlled, although only the prototype locos were built before the first 151s with series production following a little later.

The 141s were a little different, they too featured a 'steering wheel' but only with off/run down/hold/run up notches. Possibly due to them using a low voltage tap changer which was responsible for their characteristic popping sound and 'firecracker' nickname.

 

[duesselmartin]

Thanks for that explanation.
The words for 1 phase and 3 phase AC in German Wechselstrom and Drehstrom are often incorrectly used interchangeably. Hence the confusion.