Hochdruck: German High-Pressure Locomotives.

Updated: 30 May 2006
Contents of this page:
The H17 of 1925
The H02 of 1929
The H45 of 1951
Brush up Your Locomotive German
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H17

Left: H17-206 was built in 1925 by Henschel, on the Schmidt high pressure system.

4-6-0
Boiler Pressure: 1000 psi (60 kp/cm2)
Coal-fired.

Compound.
HP cyl diam 290 mm
LP cyl diam 500 mm

The H17-206 was not repeated.

H17

Left: Side elevation of the H17

The long HP steam drum is above the firebox.

Compare the French PL241B of 1929 also built by Henschel on the Schmidt high pressure system.


H02

H stands for Hochdruck- German for high pressure.
After the failure of the H17, you might be surprised that another German high-pressure loco was attempted. There was a good reason. Conventional locos were at the limit of the power that could be generated within the German loading gauge; wheels and boilers had reached maximum possible size.

Above: the high-pressure locomotive H02-1001, built in 1929. Note the small diameter of the outside cylinders. The chimney is set well back from the front of the boiler; smoke can be seen emerging in line with the front driving wheel.

The designers of this beauty meant business; steam was delivered at no less than 1750 lb/sqin (105 kp/cm) to the two very small outside cylinders of 220mm diameter, compounded with a single 600mm LP inside cylinder. Wheel arrangement was 4-6-2.
It was delivered in 1930 by Schwarzkopff, built to the design of Dr L Löffler. Schwarzkopff were brave enough to guarantee in the purchase contract a coal saving of 42% over a standard 01 design; in fact DRG never bought the loco.

Above: The steam circuit of H02. The firebox tubes carried steam only.

A Injector
K pump lockoff valve
S rotary pump
1 Air preheater
B,C setback valves (?)
L throttle valve
T heat exchanger
2 hot air duct
D HP regulator
M LP regulator
U oil separator
3 LP feed heater
E changeover valve
N HP cylinders
V condensate reservoir
4 feed pump
F security valve
O LP cylinder
W steam generator
G lockoff valve (?)
P LP superheater
X steam introduction
H overflow valve
Q HP superheater
Y saturated steam withdrawal
I blowoff valve
R HP feedheater
Z external steam inlet

The plumbing of H02 was complex, and one begins to get some idea of why maintenance costs were high. Briefly, this is how it worked...
The Schmidt system avoided scaling in the HP boiler by transferring the firebox heat through a distilled-water ultra-HP circuit. The Schwarzkopff-Löffler instead used steam alone to transfer the heat; steam cannot of course deposit scale.
Saturated steam from steam generator W was pumped through the HP superheater tubes Q which lined the firebox. There it was superheated to about 900 degF and the pressure raised to 1700 psi. Only a quarter of this was fed to the HP cylinders; the rest was returned to the steam generator to evaporate more water and continue the cycle.
The HP cylinder exhaust passed through the oil separator U, the LP feed heater 3, and then the tubes of the LP boiler T; this latter is roughly equivalent to the LP boiler in the Schmidt system, but is not heated by combustion gases. Steam was raised at here 225 psi, fed to the LP superheater, and then fed via the LP regulator M to the LP cylinder. The LP exhaust feeds the blastpipe in the smokebox.
The HP exhaust condensed in the LP boiler heating tubes was pumped back to the steam generator W.

This is all very ingenious, but contains a hidden snag... it is impossible to raise steam in this loco unless you already have steam available from somewhere else. Since the firebox tubes are cooled by steam and not water, the minimum pressure in the steam generator before the fire could be lit was 70 psi. Steam could be introduced from another locomotive by via the external steam inlet Z.

Another point is that you are absolutely dependant on the steam pump to keep going. This is probably why two were fitted, but it doesn't seem to have helped reliability much.

Above: H02-1001 on a turntable.

As with other high-pressure experiments, after extensive trials it was found that the increase in efficiency was small compared with the greatly increased costs. H02-1001 was also hopelessly unreliable. No more were built.

H02

Left: Another view of H02, without its tender. The headlight also seems to be missing.


H45

Left: Prototype T22571: German State Railroad class H45 024, 2-10-2. Loco was built in 1951
This little-known design was built in 1951 in the GDR. It had a La Mont boiler, (water-tube with pumped circulation) running at a pressure of 750 lb/sqin (42 kp/cm)
Fired by pulverised brown coal, it was intended for heavy freight trains. It made only two trial runs then was abandoned.

Left: Pictures are in short supply. This is actually a model made by Trix.

The H45 024 was built in 1951 by the state railways of the former German Democratic Republic (East Germany), based on a class 45 freight engine built by the Reichsbahn in 1941.
The H45 024 was fired with brown coal dust, like many engines in the GDR, and had a condensing tender. It had three cylinders, like the standard class 45, but was converted to compounding. The inside cylinder was replaced by a HP cylinder with the reduced diameter of 400mm. LP cylinder diameter was 520mm. By the way, it really had a brown colour, like the Trix model, possibly to make leaks of coal dust less visible.
It was a total failure. Only two test runs were made, both of which had to be stopped after a few kilometres because of multiple problems, e.g. with the condenser. The costly project was then abandoned, which implies that after so little experience the problems were already considered insuperable; these could use some explanation. H45 024 was mostly scrapped in 1961.
But... parts of it are still with us, and still running, which is even more unusual. The outside cylinders, trailing wheels and the rear part of the frame were used by the GDR to convert the streamlined tank locomotive 61 002 into Pacific 18 201. This locomotive still exists and is the fastest still-operating steam engine in the world. See below:

(Info on H45 kindly provided by Fritz Gallwitz)

Left: The 18 201 German semi-streamlined loco.

Apart from the chunks of H45 pressed into service, it used the main frame taken from the 61 002 Streamliner, and the tender from a 44 Class freight loco. The boiler was new. It is still operational in Germany, often pulling two tenders, as there are very few places in Germany to take on either fuel oil or water these days...


Brush up Your Locomotive German:

abblasen
blow off
absperren
lock off, close (valve)
Achse
axle
anheizen
heat up
blindwelle
jackshaft
brennkammer
combustion chamber
dampfeinführung
steam introduction
dampfentnahme
steam withdrawal
dampferzeuger
steam generator
drossel
throttle
entwurf
draft (ie initial drawing)
feuerraumteil
heating space
fremddampf
foreign (ie external) steam
feuerbüchse
firebox
gattung
type
getriebe
transmission
heizöl
fuel oil
hochdruck
high pressure
kessel
boiler
kolbenhub
piston stroke
Kuppelstange
coupling rod
kurbel
crank
niederdruck
low pressure
oelabscheider
oil separator
ofen
firebox ? (lit. stove)
ölkühler
oil cooler
rad
wheel
regler
automatic controller
rückschlagventil
check valve
schmieröl
lubricating oil
schnellzug
express train
sicherheits
safety
sicherheitsventil
safety valve
speisewasser
feed water
strahlpumpe
jet pump (injector)
überhitzer
superheater
überhitzerrohe
superheater tubes
überström
overflow
treibraddurchmesser
driving wheel diameter
ventil
valve
ventile
valves
verdampferrohe
evaporator tubes
verdampfung
evaporation
verdichter
compressor
wärmeaustauscher
heat exchanger
wechselventil
change valve
welle
shaft, axle
ä ë ö ü ß

I am no linguist. If any of this is embarrassingly wrong, please let me know.

There is a proper German-English locomotive dictionary at: http://www.frankenbahn.de/woerterbuch/woerterbuch.htm

See also: http://www.worldrailfans.org/Germany/Dictionary.shtml

Bibliography: Dampf Lok Stoffels
Typenbuch deutscher Lokomotiven. (type book of German locomotives)

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