Class 73. Changing from diesel to electric.

[pauliebanger]

I have received conflicting information on this topic, so I hope someone can give me the definitive answers.

 

Until recently, I was under the impression that the power supply could be switched from electric to diesel and vice versa without needing to come to a halt, ie. on the move.

 

However, having now operated the control levers in a Class 73, it appears that they are interlocked in some way, and anecdotal evidence I've gathered since seems to strongly suggest that all such manoeuvres are carried out when stationary. This latter view may be as a result of operational instructions rather than design. 

 

I would like to know:

 

1) Is power supply switching technically/physically possible whilst moving?

2)If so, was/is it normal practice to do so?

3) Do any speed restrictions apply when such switching can occur?

4) Are the collecting shoes on both sides lowered and raised together, or is each side operated separately? (I could only see a single button on the driving desk). 

 

Any additional info regarding Class 73 operations would also be very gratefully received.

 

Thank you,

 

Paul

[The Bigbee Line]

1) Is power supply switching technically/physically possible whilst moving? IIRC changeover took over on the move

2)If so, was/is it normal practice to do so?  IIRC yes, stopping would be a pain, as well as an operational nightmare.

3) Do any speed restrictions apply when such switching can occur?  Not that I'm aware of

4) Are the collecting shoes on both sides lowered and raised together, or is each side operated separately? (I could only see a single button on the driving desk). All shoes up or all down

 

I have a 1960's doc scanned somewhere I'll try and find it

[pauliebanger]

1) Is power supply switching technically/physically possible whilst moving? IIRC changeover took over on the move

2)If so, was/is it normal practice to do so?  IIRC yes, stopping would be a pain, as well as an operational nightmare.

3) Do any speed restrictions apply when such switching can occur?  Not that I'm aware of

4) Are the collecting shoes on both sides lowered and raised together, or is each side operated separately? (I could only see a single button on the driving desk). All shoes up or all down

 

I have a 1960's doc scanned somewhere I'll try and find it

 Ernie,

 

Thank you for your rapid response. Any documentation would be very helpful. Do you know how the dual controllers were operated, and how the driver actually performs the change over? Lowering and raising of the shoes would be part of it for sure, but I assume there would be something more 'heavyweight' to change the (high) power supplies than the shoes' push button.

 

Kind regards,

 

Paul

[eastwestdivide]

2) I recall watching 73s on heavy trains (e.g. 8-9 100T Brett aggregate hoppers) come round the curve at Strood, switching to diesel to take them over the junction (with all its gaps) when heading for the gradient over Strood High Street towards Cuxton. Presumably to avoid snatching over the gaps in the conductor rail and to give a smooth, if lower, delivery of power.

Also recall watching them approach Hoo Junction from the Gravesend direction, firing up the diesel engine as they slowed for the signal taking them into the unelectrified yard.

So I'd say it was normal practice back then (80s).

Whether that's changed in more recent years, I couldn't say.

[stewartingram]

I remember hearing of the early days of class 73 on the Gatwick Express services. Apparently a number of fires (presumably minor bogie fires) occurred when starting off from Victoria, where power was needed to accelerate away, but with the arcing occuring from the shoegear over the many crossing gaps in the conductor rails. So a change was made, whereby they started under diesel power, and upon reacing plain line, switched to electric power on the move. There was an article in a magazine, probably RAIL, which specifically emphasied this.

 

Stewart

[The Bigbee Line]

I remember hearing of the early days of class 73 on the Gatwick Express services. Apparently a number of fires (presumably minor bogie fires) occurred when starting off from Victoria, where power was needed to accelerate away, but with the arcing occuring from the shoegear over the many crossing gaps in the conductor rails. So a change was made, whereby they started under diesel power, and upon reacing plain line, switched to electric power on the move. There was an article in a magazine, probably RAIL, which specifically emphasied this.

 

Stewart

The arcing problem occurred when the 73 was driven remotely.  In normal loco hauling mode, the driver would shut off at a large gap, allowing the control camshaft to run back.  This reduced the current flowing and no large arc occurred.  On occasions with 73's severe damage could still occur,  I was at Shepherdswell with a train of empty MDV's for the colliery.  We arrived from the Dover Priory direction and stopped at the platform starter.  After deciding on the moves that would take place the signalman cleared the signal.  As the train drew forward there was a ripping sound and a cloud of brown smoke.  As the trailing shoe on the offside left the ramp end it drew an arc that jumped to the steps.  Needless to say a large portion of the step was burnt away.  In hindsight the driver should have started on diesel.....

The control gear was altered to reduce the possibility of arcs occurring (Don't ask me how that was done.  The effect was to reduce the potential power output on DC, much to some drivers distain )  The bogies were also fitted with fibreglass arc protectors to go between the shoe gear and the bogie frames.

[The Stationmaster]

The arcing problem occurred when the 73 was driven remotely.  In normal loco hauling mode, the driver would shut off at a large gap, allowing the control camshaft to run back.  This reduced the current flowing and no large arc occurred.  On occasions with 73's severe damage could still occur,  I was at Shepherdswell with a train of empty MDV's for the colliery.  We arrived from the Dover Priory direction and stopped at the platform starter.  After deciding on the moves that would take place the signalman cleared the signal.  As the train drew forward there was a ripping sound and a cloud of brown smoke.  As the trailing shoe on the offside left the ramp end it drew an arc that jumped to the steps.  Needless to say a large portion of the step was burnt away.  In hindsight the driver should have started on diesel.....

The control gear was altered to reduce the possibility of arcs occurring (Don't ask me how that was done.  The effect was to reduce the potential power output on DC, much to some drivers distain )  The bogies were also fitted with fibreglass arc protectors to go between the shoe gear and the bogie frames.

OOps - nobody told me they did things like that (well I was off the Western and not into Southern ways) so maybe it's just as well my plan to use one as a set of pick-ups didn't come off

[The Bigbee Line]

Starting on diesel might have been a good temporary fix                                                                                                                                                                                                                                            

[The Stationmaster]

Starting on diesel might have been a good temporary fix                                                                                                                                                                                                                                            

Not for that job - the loco would have been unmanned and simply collecting current for the train supply.

[The Bigbee Line]

The driver can start the 73 diesel from the GLV

[The Stationmaster]

The driver can start the 73 diesel from the GLV

But not from a Class 92

[meld]

Hi All,

 

ED's have Twin Power controller handles.

 

One above the other and of different Profiles, One Ovoid and One Square.

 

If you had started the diesel engine previously and needed to change over from one power supply to the other it was a simple case of closing the Controller, waiting for the control gear to run back to neutral and then pull the other one open. This action could be done on the move.

 

The Electric controller is the one above the Diesel one.

 

If sitting on the Right it was always advisable not to rest your left hand over the open, active lower controller handle as if your Driver 'threw the handle back' you could get a trapped and broken Hand/wrist/fingers as the gap narrowed between the two !!!!!!!!!!!

 

All you had to do was to remeber to make sure you had activaed the air supply to the cylinders to push the Collector shoes down, All shoes on each Bogie were mounted on a Spring loaded & hinged 'Frame' and were lowered at the same time by this action.

 

( IIRC if you started the diesel engine it opened the air exhaust valve on the cylinders for the shoe activation and allowed the Spring raised the shoes anyway, meaning you had to re-lower them to continue on 3rd rail supply )

 

HTH.

 

MC

 

 

[Southernman46]

And probably the most versatile loco's BR had.................................

 

and they went like sh*te off a shovel when running light 

[pauliebanger]

Thank you all for your insights. Most informative.

 

As is often the case, the answers generate more questions.

 

I get a picture that the frame holding the shoes is normally held in the raised position, and needs to be pushed by air against a spring to lower the shoes. Is that a correct interpretation?

 

If so, where does the air pressure come from to lower the shoes at the start of duty? Is the diesel engine run first each time to power the compressor? Is there some other way to power the compressor when the shoes are up and the diesel engine not running? Presumably, the compressor would be powered by the rail during operations on the juice?

 

I'm sorry about my ignorance in these matters, but I'm from 'North of Watford Gap' so have not seen these details in action. I'm just getting to the point at which I'm beginning to know what it is that I don't know!

 

I know for instance that locos with pantographs may have a small generating set to raise the panto initially. But I've no idea if 3rd rail locos and emus generally are stabled with shoes up or down. I would assume 'up' for safety, but is that correct? I can see I need to undertake a bit more research into 3rd rail practice. 

 

Thanks again for your responses,

 

Kind regards,

 

Paul

[Bert Cheese]

The shoes are normally in the down position in service.

They are raised when the master controller is moved to "Forward Parallel" or "Reverse" and the diesel controller is moved from "Lock Off" to "Off"

The above movement of the diesel controller de-energises the shoe down valve and the shoes are raised for diesel running, this valve can be isolated via the auxiliary isolating switch.

Should no residual control air be present it is of course necessary to run the engine up in order to raise the shoes before moving off.

 

It is also possible to drive the loco using the electric controller handle to control the diesel engine in auxiliary mode via the Westcode system, though only 4 notches are available as per when being controlled from a remote driving cab of a TC set or similar....the lower diesel controller giving variable power control directly through the governor.

 

Most 3rd rail stock have fixed shoe beams constantly in touch with the 3rd rail, the ED's of course needing to be able to raise theirs when running off the juice.

[pauliebanger]

Thanks, a lot of detail in your response which has helped to fill the gap.

 

I like your idea on bacon, too!

 

Paul