Roundhouse Alco

[Chris Cairns]

What would be the expectant running time for this loco? I’m aware that its gas tank (Type L?) has a slightly smaller volume (30ml) compared to a Type A (32.29ml) but the running time I’m getting is much lower than my Billy, Katie & Silver Lady. So I’ve adopted part of my Accucraft running technique – bring Alco up to 25–30 PSI & clear cylinders of water/condensate. Turn off burner & refill gas tank. Wait about 2 mins for gas tank to settle, lit up loco & then get a running time of approx. 18–20 mins (usually around 30 mins with the other locos above on one fill of gas). Safety valve set correctly, running at 25–30 PSI not blowing off & no obvious steam leaks.

Is it also normal to get the exhaust condensate flooding the running plate in front of the smoke box, and if so is there an easy modification to divert it to below the loco? I’d like to add some detailing parts (re-railing jacks, sleepers, etc.) but the loco currently gets rather messy there during a run. Not taken it apart yet but think it has the exhaust enhancer fitted rather than a chuffer.

Chris Cairns

[GTB]

What would be the expectant running time for this loco?

The Alco and Mountaineer locos have smaller boilers than the Type 1 boiler fitted to locos like Lady Anne. Presumably Roundhouse fit the slightly smaller gas tank so the gas still runs out before the water.

My experience of Roundhouse locos is they use an average of 1 ml per min of butane and 5ml per minute of water during a run.

Assuming the burner is turned down to almost silent and the safety isn't blowing off during the run, I'd expect this loco to run for 28-30 min and still have about 40 ml of water left in the boiler when the gas runs out.

Is this a new loco., or secondhand/used?

If brand new, I'd be talking to Roundhouse. If used, there are a few things to check.

Check the gas tank is filling properly, as the filler valve could be faulty. 30 ml of butane liquid weighs 18g and if you have a set of digital scales that read to 1g, the amount added can be checked by weighing the gas canister before and after filling the loco gas tank. You should be able to smell gas leaks, but make sure by checking all the joints for leaks with soapy water.

Check that some bright spark hasn't decided to fit a larger burner jet, or bored out the original, so the burner uses more gas.

If the cylinders are using excessive amounts of steam, it should show up as having to keep the burner on high to maintain pressure, which will reduce gas run time.

Check that the D valves are properly seated. When in steam, put the loco in mid gear and open the throttle. A sticky D valve will make itself known by the sound of escaping steam through the smokebox.

Can't think of much else. Might be worth checking the valve timing, if you can't find anything else wrong.

Not having an Alco, I'm not sure why the front apron floods, but my #24 is usually a bit oily around the bottom of the smokebox. The smokebox sits on the front apron and the hole in the apron is smaller than the base of the smokebox, so it tends to accumulate oil in the corners, which then seeps out onto the apron. Roundhouse don't make fitting smokeboxes easy and if someone has had this one apart, it just may not be fitted properly, leaving a gap for oily water to escape through.

Regards,
Graeme

[Chris Cairns]

Graeme,

Many thanks for your comprehensive reply.

The Alco was sold 2nd hand by a reputable trader, listed as 'Hardly Used'. However it was obvious that it had never been used since purchase from Roundhouse.

It does not have a full body cast smokebox like the Billy one, or the Katie/Lady Anne one.



The wrapper does not fit together at the bottom so there is a prominent slot which the oil is using to flow forward. The superheater pipe & combined exhaust pipe are also right up against the front of the smokebox bottom hole. I've sealed the front to the wrapper & filed that slot with some silicone to hopefully reduce the condensate flowing forward (photo below taken before doing that)



There are no gas leaks & it is a standard No.20 Roundhouse jet. I like your idea of weighing the gas canister before & after filling, but I do not have any digital scales, and I'm using mixed gas at present. If there is no change on the next run I'll try a different gas filler valve.

The lifting arms were in slightly different positions when in mid gear (now corrected).

Need to wait for a suitable weather window, as yesterday's running day was cancelled due to 2" of snow.

Chris Cairns

[GTB]

It does not have a full body cast smokebox like the Billy one, or the Katie/Lady Anne one.

The smokebox design is much the same as the one on #24, except that my #24 doesn't have as big a gap along the bottom joint when the clamping screw is tightened.

I like your idea of weighing the gas canister before & after filling, but I do not have any digital scales, and I'm using mixed gas at present.

There's not much difference in density between butane and propane in liquid form. The density of 70/30 mixed gas will be slightly lower than butane, but the difference in weight in a 30ml tank won't be seen by ordinary digital kitchen scales.

Mine cost me the equivalent of 20 quid from the local discount store. Not a necessary workshop tool by any means, but useful when testing locos, mixing resins, etc.

Measuring the water use during a run will confirm if the cylinders/valve gear are OK. Looking at the condition of the model in the photos, I think you are right that it has done very little running.

Need to wait for a suitable weather window, as yesterday's running day was cancelled due to 2" of snow.

What's snow? It was +30C in my workshop on Sunday.......

Regards,
Graeme

[Chris Cairns]

Here's my Alco front after 2 runs last Saturday. My sealant has reduced, but not eliminated, the condensate that now collects on the front running plate.



The 2 runs were again just under 20 mins each, so no difference there. We have a workshop/running day tomorrow so I'll see if our host has digital scales & try fitting another gas filler valve.

Chris Cairns

[Chris Cairns]

Replaced the gas filler valve, and weighed my gas canister on analogue scales which gave approx. 20g, so no problem with the gas tank.

Just have to accept that it does have a shorter running time, and if I need to run for longer whilst operating at shows, then stop for a convenient water/gas refill.

Chris Cairns

[GTB]

Just have to accept that it does have a shorter running time, and if I need to run for longer whilst operating at shows, then stop for a convenient water/gas refill.

Chris,

OK. That means the loco is burning gas at a rate 50% higher than I see on my Roundhouse based locos. The safety valve on my Roundhouse locos would be roaring it's head off and the boiler pressure would be 45 psi at that combustion rate.

Is that the case? If the safety valve on the Alco isn't wide open during a run, then the cylinders are wasting an awful lot of steam. Either a D valve is not seated properly, or a piston ring is faulty.

I fit a little handle on my gas valves so I can easily read the gas setting. For the purpose of this experiment, use a marking pen to make a vertical line on the front of the valve knob when it is closed. If it was a clock face the line would be pointing at 12.

The gas flow will be at a maximum once the valve is open half a turn, ie. pointing at 6. This is where I set it when steaming up from cold. Once the pressure gets to about 35psi I cut the gas back to about an eighth of a turn to stop the safety blowing off and leave it there during the run, ie. pointing somewhere between 10 and 11. This setting is about as low as a RH burner will go and reliably stay alight during a run.

Just so we are on the same page, I time a run from when the burner is lit, to when the gas runs out.......

You said you were running with butane/propane mixture. For obvious reasons I don't use it and I don't think I've seen it on sale locally.

I know you need it to light up in very cold weather, but once the boiler has come up to pressure and heated the gas tank, the gas pressure will be higher than it would otherwise be with butane and therefore the gas flow will be higher for a given gas valve setting. Running in cold weather with mixed gas would I think require lower gas settings once pressure is up than would be used with butane.

Regards,
Graeme

[artfull dodger]

All I run here in the USA is Iso-butane as its easily sourced from the local Walmart. The weather here can be from one extreme to the other(hot/cold). I, like Graeme run a full half turn open once the burner stablizes to heat up from cold start up. Once pressure is up, I cut it back till the burner noise is almost totally gone, which is about the same setting as he is using. Roundhouse burners are so much more efficient than other brands. I would say something is amiss on that engine and needs adjusted. There is a gentleman in the USA that posts alot over on My Large Scale named Dave Meshey. You might join up over there and send him a message. He has one of these engines and runs it quite alot and is very happy with it. Might make a good benchmark to compare steaming notes with. Mike

[Chris Cairns]

Hopefully 3rd time lucky posting a reply.

Just so we are on the same page, I time a run from when the burner is lit, to when the gas runs out.......

bring Alco up to 25–30 PSI & clear cylinders of water/condensate. Turn off burner & refill gas tank. Wait about 2 mins for gas tank to settle, light up loco & then get a running time of approx. 18–20 mins (usually around 30 mins with the other locos above on one fill of gas).

So my running times are the actual time the loco will run after 'coming off shed', rather than the burner lit time.

A friend brought his Alco to the workshop/running day today so I could time it for a comparison. First run was with 1 fill of gas, and it ran for just over 15 mins after coming off shed. 2nd run was brought up to working pressure & cylinders cleared, gas turned off, tank refilled, and this run then lasted 19 minutes after coming off shed.

So these locos do have a shorter run compared to other Classic Series locos - I turned the gas off on my Katie after 25 mins running today (as lunch was served up) and my Silver Lady lasted approx. 30 mins (forgot to start the stopwatch for that run).

Chris Cairns

[GTB]

So these locos do have a shorter run compared to other Classic Series locos - I turned the gas off on my Katie after 25 mins running today (as lunch was served up) and my Silver Lady lasted approx. 30 mins (forgot to start the stopwatch for that run).

Your Katie and Silver Lady runs are about the same as I expect to get from my RH based locos with the same size boiler.

Perhaps the Alco is designed for shorter runs, to take account of the smaller boiler. You learn something new every day.

Graeme