Durango to Silverton Railroad

[peter scott]

The remaining part of a network of narrow gauge lines serving gold and silver mines in the 19th and early 20th centuries is now given over to tourists. Pam and I much enjoyed this trip last month, Pam sticking her smart phone out the right hand side and me on the left. If you can put up with the amateur filming I think it gives a fair impression of the trip.

The three and a half hour journey is condensed into 30 minutes. Watch as the coal fueled locomotive hauls the train of 10 passenger coaches from 6500 ft altitude in Durango to 9300 ft in Silverton just 45 miles distant. A fireman needs to shovel about 5 tons of coal for the round trip to Silverton and back. Most of which is needed on the uphill journey shown in this video. The train follows the path of the Animas river that on this trip was in spate. Note how close the track is to the river. A constant erosion  challenge for those maintaining the track. En route the locomotive takes on water and also periodically blows out water from its cylinders.

https://youtu.be/eBUhMsp0n6k

On arrival at Silverton we had lunch in really atmospheric bar with a very good pianist playing Scott Joplin ragtime.

   

Peter

[Terry]

En route the locomotive takes on water and also periodically blows out water from its cylinders.

What do you mean by 'periodically', Peter?

When a locomotive comes to a standstill, the cylinders start to cool down and any remaining steam condenses. When steam is readmitted to start the loco again, some of this will also condense as it comes into contact with the cooler (or even cold) cylinders and pistons.

This causes a problem as, whilst steam can be compressed, water cannot so that, when the piston reaches the end of the cylinder, a hydraulic explosion is possible. I've seen a cylinder to which this has happened with the end completely blown off. It was on a Southern Region Merchant Navy which was immediately withdrawn when the incident happened. (It was subsequently bought for possible restoration because it was in particularly good mechanical condition because of its premature scrapping.)

What had happened is that the footplate crew had either failed to open the drain cocks or shut them again before the cylinders were hot enough when pulling away after a station stop.

Opening the cocks and flushing out the cylinders, then leaving them open until the correct working temperature is reached is a rigidly observed routine whenever the loco (re)starts but I wouldn't expect to see it at any other time except, possibly, if the loco had been coasting downhill for a reasonable length of time, which obviously wouldn't be the case here!

[peter scott]

Hi Terry,

I take your points about when water might condense in the cylinders and I did wonder why they were doing it but it really was periodic and the locomotive was steadily climbing on this run with next to no opportunity for coasting. Perhaps I misunderstood what the steam releases were for but it appeared to be from near the front of the loco, one side at a time.

Peter

   

[peter scott]

Terry, You are right. I misunderstood where the steam was coming from. Apparently "the fireman and engineer alternately open the "blowdown" valve to clear sediment that accumulates in the bottom of the boiler." Quoted from the D&S Official Guidebook.

Thanks,

Peter

[Terry]

Yes - the steam in the view you showed was coming from the side of the loco - steam from the drain cocks is usually ejected  towards the front. This is a typical arrangement - the copper pipes show up well in this picture:

[peter scott]

Terry, You are right. I misunderstood where the steam was coming from. Apparently "the fireman and engineer alternately open the "blowdown" valve to clear sediment that accumulates in the bottom of the boiler." Quoted from the D&S Official Guidebook.

Thanks,

Peter

   

[Refugee]

I was always under the impression that any purging was done in front of the front wheels so that it doubles up as a leaf clearance device.

[Andy M0FYA]

'Purging', not a word I associate with steam locomotives, but do associate with removing contaminants from the fuel cells used on the Apollo and Space Shuttle programmes.

Cylinder drain cocks tend to be at the front of a locomotive because that's where the cylinders are located, at least on a conventional locomotive as distinct from an articulated design or a Shay, and the boiler blowdown is at the back because that is where the firebox is located (again, on a conventional locomotive).

That blowdown valve terrifies me - if the linkage fails with the valve open there must be a real risk of emptying the boiler with disastrous consequences!

Andy

[peter scott]

"There are valves placed low in the water space, usually along the outside of the water space of the sides of the firebox, that can be opened to allow the water to escape (quite violently) and in that process it takes some of the sediment with it. It also reduces the amount of water in the boiler and that MUST be replenished with more water. In that process, the concentration of impurities in the water goes down on the whole (less water in the boiler that has a high concentration of impurities, plus more water that has less impurities) and so less material is available to precipitate out and collect on the boiler interior."