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DONCASTER WORKS

 

PART 37  -  SLIDE AND PISTON VALVES

 

Under Stirling the steam chests (with their vertical slide valves) were cast integral with the cylinders.  The castings were usually located between the main frames, but on the 4-2-2s the castings were straddled by the frames, with the cylinders on the outside and the steam chests (containing the slide valves) on the inside. Stirling had been forced into this situation because of their 8ft diameter driving wheels, as otherwise the boiler barrel would have been pitched unacceptably high to clear the (inside) connecting rod cranks at top centre.  Now the boiler only had to clear the eccentrics for the (inside) valve gear.  (When larger diameter boilers were introduced in 1880, the pitch of the boiler was raised a further in.).  The clearance was tight, so much so that the lagging had to be cut away to clear the inner eccentric straps, see lower illustration on p. 55 of THE STIRLING SINGLES (David & Charles, 1965).  However, it is possible this treatment was quite normal practice for the earlier engines from 1880, as perhaps the Works did not bother to raise the height on existing engines, but chose instead to cut away the lagging to provide the clearance.

 

Changes were made under Ivatt.  As far as his two-cylinder designs were concerned, only his 4-4-2s (which were perhaps based on the Stirling 4-2-2s rather than on his own 4-4-0s) had outside cylinders.  Ivatt introduced horizontal balanced slide valves above the cylinders for his 0-8-0s which had large diameter cylinders, leaving insufficient room for vertical balanced slide valves between them.  Over the next few years there was a mix of slide, balanced slide and piston valves, which was not straightforward.  The list below covers the various classes (mostly with Stephenson valve gear), showing the various combinations. In general, the position with engines having Walschaerts valve gear was straight-forward, as the valve gear, cylinders and steam chest (with piston valves) were (normally) outside the frames.

 

Dwg.
No.

Cylinder
Pattern
No.
Date GNR
Engine Class

LNER
Engine
Class

First
Engine
Date Cylinders
position
Cylinder PV Diameter  

Valve
Type

Location of Valves
(v)
M64 26
26
26B
26B
26B
12/1895 J14
J13
N1
J21
J22
J53
J52
N1
J1
J5
-
1201
190
1
31
-
8/1897
4/1907
5/1908
10/1909
Inside 18" SV Vertical
M229 26 -/1918 N1 N1 1598 2/1918 Inside 19" BSV Above
M66 28 4/1896 E1 E1 1061 2/1897 Inside 17" SV Vertical
M112 28 -/1906           18" BSV? Above?
M67 29 7/1896 D2 D4 400 12/1896 Inside 17" SV Vertical
M79 29 12/1898 D2 D4 1341 12/1898 Inside 17" BSV Above?
M133 29 11/1908 D1 D2 41 4/1909 Inside 17" BSV Above?
M69 30 1/1897 C2 C12 1009 2/1898 Inside 17" SV Vertical
M86 30A 7/1900 C2 C12 1531 12/1903 Inside 18" SV Vertical
M71 31 2/1897 C1 C2
C1
990
251
5/1898
12/1902
Outside 18" BSV Vertical
M74 (b) 31 11/1897 C1 C2 990 5/1898 Outside 18" BSV Vertical
M166 31   C1 C1/C2     Outside 19" BSV Vertical
M73 ?32 7/1897 A4   266 10/1898 Inside 19" BSV Above
M78 33 7/1898 A5 - 267 5/1900 Inside 19" BSV Above
M81 34 9/1900 C1 - 271 7/1902 Inside
Outside
15"
15"
PV
PV
Above
Above
      C1 - 271 9/1904 Inside
Outside
15"
15"
BSV
BSV
Above
Above
M85 35 6/1900 K1 Q1 401 2/1901 Inside 19" BSV Above
M86 36 7/1900 C2 C12 1521 6/1901 Inside 18"    
M99 37   C1 C1 292 3/1905 Inside
Outside
16" LP
13" HP
BSV
BSV (w)
?
Above
      C1 - 1300 7/1905 Inside
Outside
23" LP
14" HP
(w)
(w)
 
      C1 C1 1300 11/1917 Outside 20" PV (w) Above
M114 39 3/1906 C1 C1 1421 8/1907 Inside
Outside
16" LP
13" HP
BSV (w)
BSV (w)
Above
Above
M127 42 6/1908 K1 Q2 417 12/1908 Inside 20" PV Above
M136 42A 5/1909 K1 Q2 451 9/1909 Inside 21" PV Above
M131 43 9/1908 C1 C2
C1
988
1452
5/1909
8/1910
Outside 20" PV Alongside
M140 44 9/1910 D1
C1
D1
C2
51
271
3/1911
7/1911
Inside 18" PV Above
M145 45 2/1911 J22
J21
N2
J6
J2
N2
521
71
1606
8/1911
8/1912
12/1920
Inside 19" PV Above
M179 48 6/1913 J23 J51 157 12/1913 Inside 18" SV Vertical
M188     J23 J51 167 4/1914 Inside 18" BSV Vertical
M179 48 6/1913 J23 J50 3231 2/1924 Inside 18" SV Vertical

 

SV Valves; BSV Balanced Slide Valves; PV Piston Valves

LP Low Pressure; HP High Pressure

(b) First Doncaster drawing specifically marked Balanced Slide Valve

(v) SV/BSV Vertical were positioned between the inside cylinders;

                Above were positioned above the cylinders;
               Alongside were positioned adjacent to the outside cylinders, but between the frames

(w) Walschaerts valve gear (otherwise Stephenson valve gear)

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