Pacer revving at intermediate stations

[ryan125hst]

I went from Retford to Meadowhall by train on Saturday and, on the return journey, the Class 142 I was on revved while stationary at about three intermediate stations.

It first revved like that at Kiverton Park and my first thought was that the driver had tried to take power when the doors were open. However, the same thing happened again at Worksop, and when I got off at Retford, the engines were revving loudly once again as I left the train and walked down the platform. I got off at the front door and it wasn't until I got to the back of the train, a second or so before the guard pressed the door close button, that the revving stopped.

Does anyone have any ideas as to why the train was doing this? My thoughts are that it was either a problem with the air brakes requiring the engines to be revved to build up air (maybe a leak in the main reservoir or one of the compressors was broken), or an electrical fault.

Many thanks

Ryan

 

[61653 HTAFC]

Was the driver wearing a Burberry cap?

 

[Bletchleyite]

This happens to build up air if the reservoir gets low. It's not very common other than on startup, so that would to me suggest a possible leak and thus a need to top up more than normal.

 

[pemma]

I've heard it happen before but it's certainly not as common as the Merseyrail 507s and 508s which just rev at random times. They can start revving when the doors open and go completely quiet before the doors are closed.

 

[TC60054]

I've heard it happen before but it's certainly not as common as the Merseyrail 507s and 508s which just rev at random times. They can start revving when the doors open and go completely quiet before the doors are closed.

That's the air compressor. An EMU cannot rev, it doesn't have an engine to rev

 

[coxxy]

As everyone says he probably had a problem with main air pressure and used the compressor speed up button to build the air in the unit. This can't be done when the train is moving so has to do it when stopped at a station.

 

[co-tr-paul]

You can get the same thing on a bus... .

 

[gimmea50anyday]

Heard voyagers and 185' s doing that. Could be a fault with engine management system

 

[Rail Blues]

Was the driver wearing a Burberry cap?

Imagine what fun you could have customising a Pacer. It would be very apt given they're the rail equivalent of a knackered 16 year old Corsa that's perilously close to the scrapyard.


A vast exhaust the size of a cannon, the windows tinted and the rear cab filled with a sound system that would cause cardiac arrest if the volume turned up beyond number three would look good.

 

[edwin_m]

Heard voyagers and 185' s doing that. Could be a fault with engine management system

Does a Pacer have anything that sophisticated?

I had the same on a 158 in the latter days of Central Trains when the were clapped out. The driver apologised over the PA that there was an air leak and he had to stop several times on the descent through Chinley to allow the reservoir to pump up. Similar many years ago on a 156 going down the Conwy Valley - I presume on long downhills the engine is idling so the compressor doesn't make much air.

 

[gimmea50anyday]

I wasnt thinking sophisticated electronic computer jobby but even old normally aspirated engines have some sort of engine management. Something has to trigger the spark or let the fuel in etc....

 

[Bletchleyite]

I wasnt thonking sophisticated electronic computer jobby but even old normally aspiratedengines have some sort of engine management. Something has to trigger the spark or let the fuel in etc....

The timing on diesel engines of that vintage (and indeed petrol ones) is mechanical. On a petrol engine it's the distributor that decides when to spark, which is a rotating arm with contacts. On a diesel there is no spark

I've had a Land Rover Series 3 before - nothing electronic on that at all.

 

[CosherB]

That's the air compressor. An EMU cannot rev, it doesn't have an engine to rev

That's what I thought too!

 

[FordFocus]

Heard voyagers and 185' s doing that. Could be a fault with engine management system

Think that's 'hunting for fuel' syndrome. 185s were quite known for it and Voyagers have the same engines.

The 14x and 15x family are known for not been able to hold their air. When a unit has a weak compressor, an air leak or a value not closing correctly the train may lose too much air that the brakes will automatically apply as the 'low main air governor' switch has triggered. The driver cannot override this system or isolate the switch.

The train produces air whilst the engines are running but if they are idling at speed there may not be enough air been produced. The more engine revs = the quicker the air is produced. Use of the brake, horn, wipers and doors all use air.

The common cure is to try and build up as much as air as you can through the 'compressor speed up' switch in the cab whilst stopped at a station or at a signal which revs the engines around 60%. This should build up enough air to get you to your next station and avoid the emergency brake applying mid journey. If that doesn't work the driver may have to investigate the leak, isolate certain air systems or have assistance from another train.

Hope this helps!
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Does a Pacer have anything that sophisticated?

I had the same on a 158 in the latter days of Central Trains when the were clapped out. The driver apologised over the PA that there was an air leak and he had to stop several times on the descent through Chinley to allow the reservoir to pump up. Similar many years ago on a 156 going down the Conwy Valley - I presume on long downhills the engine is idling so the compressor doesn't make much air.

Sounds like a weak compressor or an engine may have shut down en route on the 156. If your going down hill and your constantly applying and reapply the brake, it uses more air. Say the line speed is 60mph, apply the brake once to drop the speed by around 10mph (depending on the gradient) to save air than releasing it at 57mph several times during the descent.

 

[ryan125hst]

Thanks for your responses all. I thought it might be the case, but I wasn't 100% sure. I've used that line a lot over the last couple of years and it's the first time it has happened on a train I have been on.

 

[gimmea50anyday]

So what I would love to know is what causes that hunting effect I see on the QSK19s. I notices 37 409 was also doing it when I did a dash along the cumbria coast the other day. Was ok once it powered up for traction just as hunting 185s do....

And yes I know diesels dont need a spark to make the cylinder go bang, my point about something needing to manage the engine was just as mechanical and physical as electronic....

 

[FordFocus]

Had a brief search on the forum and found this post from 7 years ago..

http://www.railforums.co.uk/showpost.php?p=302665&postcount=26

The uneven idling is caused by the engine ECU taking it in turns not to inject fuel into a cylinder. This is done on a cyclical system so the sequence will start with number one cylinder and move progressively down the rack and then start at one again. (Well thats what the nice man at Scania told me about Cummins engined lorries today).

It is also possible that there are also running on Bio fuel. As this will make the engine sound different