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I bought an Aster BR96 many years ago at an auction. I fired it up once but it has sat on a shelf ever since. It is an awesome engine - a 0-8-0 0-8-0 Mallet with compounding cylinders.

This weekend, I decided the time had come to get her out on the track. Oiled up, she came up to steam pretty quickly and, once the cylinders had cleared, initially pulled very strongly with a load of 6 heavy J&M coaches.

My observation after a couple of runs is that she was very tempermental - alternating between pulling strongly with the throttle just cracked open to hardly pulling at all with a wide open throttle with plenty of steam pressure. Frustrating as she would slow down, I would open the throttle, she would limp along for a while and then suddenly spring back to pulling strongly.

I suspect this is connected with the compounding and was wondering whether anyone else has experience with this machine that could help. There is a compounding bypass valve at the front which I think simply diverts the steam from the rear engine directly up the stack when open but not sure as I don't have any instructions. In any event, it didn't seem to make a lot of difference open or closed.

Robert
 

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Hi Robert,

This wonderfull engine is proudly presented in my collection. Due to it's complexity it can be somewhat temperamentfull.
The compound bypass-valve is to be opened while starting a run. Once warmed up, and after clearing the condensated water from the front (low pressure) cilinders, it can be closed. Leaving it open excludes the low pressure running gear, resulting in reducing performance.

I've encountered issues with the connection/synchronisation of the valve gear between the rear (high pressure) en front (low pressure) engine. The high pressure engine was accidentally running pretty notched up, resulting in lower power and less exhaust steam supplied to the low pressure engine, further reducing power.

The axle driven feed pump is an "energy drain" when pumping water against the boiler pressure. Did you run the locomotive with an open or closed water-feed-bypass-valve?

You mentioned the locomotive was "decommisioned" for a while. Maybe the valve gear needs some attention (i.e. sticky oil/grease residue). Debris from deteriorated gland packings for the pistions and valves can result in poor performance.
I recommend to oil all moving parts and check operation with ~1.5 bar air pressure. You can split the locomotive in 2 engines, high pressure and low pressure. Each separate engine needs to be fully functional.

I hope I've helped you to re-activate your Aster BR96.


Met vriendelijke groet (best regards), Rob
 

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Robert, the advice given above is correct so check all he says and while I have not operated an Aster BR96 but I do have a 4 cylinder compound Aster Nord and that it has a slight delay in the regulator response not instant like a non compound engine.
So do you experience something like this; when it's running and it needs a bit more steam for load or gradient you open the regulator a bit more, then nothing seems to change straight away, so you open the regulator some more where it gets better then it really takes off. Similar but smaller delay on closing the regulator and does it run away fast on downhill gradients if you don't adjust regulator down just before the crest?
My loco behaves like this and I put this down to being a compound where the low pressure cylinders have a delay in getting fed from the high pressure cylinders especially in tiny models like ours with small ports and cylinders as well as a relatively low boiler pressure.
I have to think about load and gradients a little ahead of time to adjust the regulator. To me mastering the driving of a compound is very satisfying and adds another dimension to loco operation.
On level tracks opening the regulator on starting then closing down in stages as it gets up to speed, taking into account delay in response, then setting the regulator for the load for that track will see the train running well without touching the regulator, but I agree adjusting the water by pass can affect the running the engine through pumping losses and also cold water into the boiler so experience to get the right setting helps, and they can run out of water quick.
Another tip I found with mine ( a type C boiler) is to maintain only 1/2 to 2/3 approximately of water in the boiler, higher than 2/3 approx means there is a lot of water carry over and it runs "wet" with lower performance that affects a compound loco more than a simple loco and makes regulator adjustment a little more "dull". Also be aware that with four cylinders and a lot of metal the loco really needs to be all over "hot" to operate properly, a first start in cold weather can be problematic and that compound by pass valve comes in handy when starting.
Getting to know your loco's characteristics is essential and rewards good driving with great performance. I really love running my compound and your BR96 is a great loco so stay with it.
Russell
 

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One thing that I have found very helpful to know how to run the Chapelon is to run at an exhibition track that is at a constant table level or a bit higher. You can follow your engine continuously which you often can't on an outdoor pike. As exhibition running is for show, you also run long hours on end (With mine at Rail expo I ran it for about 3 and 1/2 hours) this gives you the time to master the by pass control to get your engine really running fine, or as Russel says: It gives you a good deal of practice. Youn also want to squirt a bit of hot steam into the pots before starting this warms them up which is most useful on compounds. They usually start compounding after 2 or 3 yards. Once they are compounding you usually should have all the power you need. It was comon on real compounds to have the LP valve gear set at around 60%, which is indeed more than the HP was. Notching up although always useful (Chapelon encouraged drivers to do so in his books) isn't as necessary in compounds because all your steam created in the boiler gets used up which it often didn't in two cylinder engines. Thats why on the Pennsy the Hyppos were with limited cut off to economise steam much like a compound.
 
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