Cylinder Drain Cocks

At Ottbergen, the DB 044s (3-cyl 2-10-0) at the head of the heavy goods trains which were about to attack the climb over the Teutoburgerwald to Altenbeken, would sit in the station with their cocks and regulator open for about 20 minutes prior to departure. This seemed to occur only on the night-time trains.

 

I was under the impression that on some locos opening the drain cocks shut off the atomiser steam for the cylinder lubricator. Thus sitting with the cocks shut runs the risk of the cylinders being pressurised and the loco possibly moving.

 

Not on a wonderful design like an S160!

 

I'm not sure about this, but understood it to be correct that after the B1 blew her cylinder in Fort William and caused disruption that there was a regulation that all steam engines on the mainline must leave with their cylinder cocks open and clear the system to avoid a repeat and thus delays if the engine failed because of this issue. As a result they often leave with them open for few few revolutions before closing them.

I'm sure someone else with much more experience will either confirm that, or just think that its just because it should be good practice to do this if the engine has been standing for sometime.

 

I get the feeling sometimes with some locos that they are left open because they can't get them closed properly. I have seen a few videos of newly restored Engines with say one side puffing away and it is probably that the linkages need adjusting and they haven't had chance to do it yet.

 

More than likely to be a bit of grot stuck in them. LMS locos are prone to this.

 

Yes ,on Stanier designed LMS engines,a fitter from Bletchley told me it was small pieces of metal that dropped down into the hole where the taps screwed into the cylinder ,and jammed the valve open. I questioned was it a lubrication problem in the cylinder /steam chest causing the metal to break off ,and he said more than likely.

 

It's usually pieces of broken valve rings.

 

If just overhauled there will be small bits of mill scale from steam pipes and elements as well as rust from passageways that will stop cocks shutting properly.

 

I took it as the photographers comment as being evidence available all these years later that drain cocks weren't being used, not the reason they weren't being used!

Steven

 

At the other extreme I know of a German design (Kemna) traction engine, but long converted to a roller, with twin high pressure cylinders and piston valves that is not fitted with drain cocks at all. There is provision on the cylinder block for them but there are just blanking plugs. Have suggested to the owner that it would be a good idea to do something about it, even fitting relief valves, but he doesn't seem at all concerned............

Getting back to locos, something that I would have thought as being desirable on inside cylinders ones with the valves between the cylinder bores would be a drain valve at the lowest part of the steam chest. An involvement with the last standard gauge steam loco built for the UK (Austerity J94-type No. 66 ex NCB and now at Quainton) the lower faces of the slide valves were badly pitted due to water/condensate laying in the valve chest and had to be machined to get a decent surface.

 

I have remarked on how often locomotives well warmed up and especially on the main line are running with some of the cylinder cocks blowing
- once with the Queen in the train. As I've seen it firmly stated that left leaking they become more work to fix as the sealing surfaces erode away: wether from the linkage or the sealing surface inside it should be tight. The sort of thing that begins to raise questions about the rest of the
maintenance.

 

The Maunsell Q certainly has this on the end of the valve chest - and I would assume the Q1 too which had the same chassis.

 

Some of the larger Stroudley locos - including the Gladstones as I recall - had the slide valves mounted horizontally underneath the cylinders, so that they fell away from the valve ports when steam was shut off. That allowed any condensed water to drain away into the exhaust, and meant the cylinders weren't fitted with drain cocks as they weren't needed.

Tom

 

Interesting responses. This confirms what I thought. Its not written down and is nearly entirely at the discretion of the driver.

 

Many GNRI locos also had slide valves mounted in this way, the given reason being to reduce wear. I recall a 'downside' to this practice being mentioned, but can't for the life of me remember where I came across it, or what it was.

Question: can this feature be used with balanced slide valve designs?

 

One downside I can think of is that if the condensate ends up in the exhaust it will eventually be expelled up the chimney - messy if you are standing nearby.

(Mind you, it could then be a form of justice if it ends up on that photographer who always wants to get up close to the action, and goes in front of everyone else - but the reality is that it would end up on my wife's new coat...)

Another would be the inability to drain things down reliably - possible corrosion or frost damage issues?

Steve B