Condensing apparatus on steam locomotives.

Tom, I don't think there was a separate tank - just the normal side tanks. Didn't the 97xx panniers also have a dump valve under the bunker with a large wheel on the fireman's side? Ray.

 

I visited the LTM the other weekend, and read there that the 4-4-0Ts had to have their tanks drained after two round trips because of the temperature rising in the tanks.

 

The Wild Swan Midland Engines book No 5 The Johnson 2441 Class is interesting reading. This is about the 3F 0-6-0 tanks 47200-59, some of which were fitted with condensing gear.
Both Moorgate Street and Farringdon had pit roads were the side tanks could be quickly drained of hot water and refilled.

 

An engineering drawing of a Kitson tank for the Mersey Railway shows the condensing pipe running into the front of the side tank and then carrying on horizontally until it suddenly jinks up to form a semicircle outside the tank (why?) and so vertically down to near the bottom of the tank. So far as I can see there is no fancy heat exchanger – the steam is just vented into the water at the bottom of the tank. (Most of the time, the horizontal pipe would surely be above the water level.) I cannot imagine the steam being condensed very effectively unless there was quite a depth of water in the tank, so did the enginemen have to make sure the tanks were never more than half empty? Was this why they had to discard the hot water at the end of a run instead of just topping up with cold?

 

Reading the Mersey Railway tender specification for the condensing locos it states that the tanks will be required to be as full as possible, but with a large valve under each tank to allow for rapid emptying. This would be done at Rock Ferry or Birkenhead Park. The tanks would then be re-filled with cold water. The single injector would not function once the tank water heated up , the crew then having to use one or two of the crosshead driven feed water pumps.

Bob.

 

On marine engines in my experience no cylinder lubrication was used with saturated steam. I wasn't aware of any particular issues with oil contamination on Scotch boilers -water tube is quite different.

The SAR Class 26 (Red Devil) had a feed heater, and about 10% of the exhaust steam was recovered. While it did as far as I am aware have feed pumps rather than injectors, you could deliver cold water from the injectors to the feed heater & then the boiler. Again although pumps were used rather than injectors this would be how its done in marine installations

 

Try this one for better sound effects -

 

I wonder if it was to stop water from the tanks surging back along the condensing pipes and into the blast pipe under braking, where it would then be ejected over all and sundry next time the regulator was opened?

Tom

 

Surely for the crude condensing systems used, there has to be changeover valve somewhere to send exhaust either up the blast pipe OR into the tanks. In that case no such surge would reach the blast pipe. More likely so that the horizontal pipe didn't fill with water when tanks filled, leaving it clear for the initial blast of exhaust steam to be partially condensed by the action of the water surrounding the horizontal pipe before exiting into the tank.

 

On the Midland Railway Johnson 3F 0-6-0 tanks fitted with condensing gear, the path of the exhaust is controlled by a flap in the blastpipe. This flap is worked from the cab by a linkage system that enters the smokebox on the LH side.

 

There are some interesting thoughts here. May I take up the very conspicuous pipes connecting the side tanks with the bunker tank on the 2‑6‑2Ts (and probably hidden behind the frames on the 0‑6‑4Ts)? Would these be to facilitate the rapid discharge of hot water? Presumably the specification called for a discharge outlet on both sides and not from the bunker tank, but I wonder if, in practice, it would have been done from the side nearest to the reception tank for hot water. Incidentally, water was discharged at Central Low Level, but never so far as I know from James Street when that was the Liverpool terminus.

 

Presumably such a valve might be manual operation though, so prone to the crew forgetting to shut. I know that one of the faults in the condensing gear in the Terriers was that water would surge forward back into the smokebox, to the extent that supposedly some drivers took to the ends of the pipes with a hammer to shut them up once and for all, so presumably it was a genuine problem, at least in some designs.

Tom

 

Its a shame we can't steam Cecil Rakes or The Major to find out the practicality of the arrangement fitted to the locomotives.

 

'The Major' had all of the condensing gear removed when it was sold to the Aussies. The condensing gear on 'Cecil Raikes' is intact.

Bob.

 

Bob is correct. The only sign of condensing gear on 'The Major' are the circular blanking patches on the smokebox sides. Aside of that, imagination.

 

To see a condensing loco actually working would certainly answer a lot of questions, but are there no memoirs that cover these points? How about a live-steam model?

The Mersey Railway had some very steep gradients – up to 1 in 27 – but there would apparently be no exhaust up the chimney on these stretches. Given that most of the running these engines did was in tunnel, would they have used the blower – or would that have defeated the object? Would they have been able to fire the engines inside the tunnel section without using the blower? Given the undesirability of black smoke perhaps firing could only be done outside the tunnels.

 

By all accounts it was rather grim in the tunnel even with the condensing apparatus, hence the relatively early electrification. Several of my forebears were daily commuters in steam and electric days (as was I at one point).
Would love to see the locos and other large objects in the NMGM collection in a proper display, but the way things are going for regional museums, I fear the worst.
Andrew (born Birkenhead, Mum from Crosby, Dad from Wallasey, great-grandfather commuted daily from Wallasey Grove Road to James Street).

 

Its a shame we can't steam Cecil Rakes or The Major to find out the practicality of the arrangement fitted to the locomotives.

I see there's a working N2, but I suppose that is missing some essential bits. Perhaps they could be replaced?