Drifting downgrade near Crianlarich on July 9, 1960, areBRStandard‘5MT’4-6-0 No.73077
and‘BlackFive’No. 44970 withaFortWilliamto GlasgowQueen Streetworkin g.COLOURRAIL‘K4’2-6-0 No.3442TheGreatMarquessblows off at Rannoch withaFortWillia mtoGlasgow
Queen Street train.Thepictur ewas taken in around 1937.COLOURRAILinto 1960 on the Mallaig Extension. Just as
Gresley haddesigned his‘P2’ 2-8-2specifically
for the Edinburgh to Aberdeenroad, helooked
for apowerful locotohandle the increasingly
heavy trains on the fiercer gradients oftheWest
Highland. However,amodified ‘K3’ 2-6-0 was
vetoed by the civil engineer,asw as ascheme for a
2-8-0 with5ft 2i ncoupledwheels.
Whichbrings us to the ‘K4’,athree-cylinder
2-6-0 capable of taking300tons over the line
unassisted. Completedat Darlington in 1937,
No. 3441Loch Longhad 5ft2in coupledwheels
and 180lbboiler pressure, later increased to 200lb,bringing the loco’s nominal tractive effortto
36,600lb–higher than that of any Gresley Pacific,
and making the ‘K4’the most powerful steamtype
to workregularly over the line (see Panel 1).
Possiblythe earliestknown log of ‘K4’
performance wasrecorded byOSNock and
featured in CecilJAllen’s ‘LocomotivePractice
&Performance’ contribution inTheRailway
Magazinefor January1938. Nock wrote: “...the
new engine(Loch Long)was loaded to within 14
tons of her ratedmaximum...her performance
was atriumphant success...doing about50 per
cent more work on the sameamount of coaland water asa‘K2’”. The log (Table 1) starts at
Dumbarton, from wherethe ‘K4’ accelerated to
57mphalongside the Clyde beforeslacking to take
the West Highland line proper at Craigendoran
Junction. Almostimmediately,they were in the
Highlands: from therestartatCraigendoran
(Upper),nowclosed, thesingle line climbsat
1-in-58 to Helensburgh (Upper) and
three-cylinderLoch Long,accelerating to21mph
on fullregulator and 40% cut-off, wouldhave
made mightymusic, similar to that ofasingle-
chimney ‘A3’ working hard at 30mph.Energetic
From Helensburgh the line undulates to
Garelochhead andthestartofmoreserious
climbing past Whistlefield, high above the
confluenceofLochs Long and Goil;after slacking
to 20mphfor th esingle line tablet exchange at
Garelochhead, the Mogul attained25mph on
1-in-61/58 beforeashortspell of 1-in-54with
awet rai lcaused her to ‘lose herfeet’, speed
dropping to 20½mph.
Turning inland, thegradient eases,enabling
Loch Longto attain 38mphbeforedescending
past GlenDouglasand negotiatingcheck-railed
curvatureabove the ‘K4’s’ eponymous loch, with
the jagged ridgeofThe Cobbler prominent across
the water.Int he opposite direction, as we shallsee,
this section is no placefor an ailing loco.
Ashortascentbrought No.3441 into
Arrochar &Tarbet, like other ‘Tarbets’ and
‘Tarberts’ signifyingan isthmusnarrowenough
for aboat tobe carried across it. An easy passage
alongside Loch Lomond followed to Ardlui, atAugust2019 •TheRailway Magazine•23
WorldRecord Officiall ythe world’slongest-runningrailway series,establishedin1901
Trai n: 5.45am Glasgow(Queen Street)-Mallaig
Loco: ‘K4’2-6-0 No.3441LochLong
Load: 286/305tons
Recorder: OSNock
Date: 1937Miles Timing Point Sched Actual Speed Gradient
min ms mph 1-in
0.0 DUMBARTON(C)0000- 385R
3.8 Cardro ss 550576 03F/175R
7.1 Craigendoran Jct 9431 5*/21 L/60R
9.3 Helensburgh Upper n/a 15 30/0 -58R
0.0 Helensburgh Upper 0000 -L/67R
6.9 Garelochhead 12 10 20*92F/60R
8.2 MP 10 14 37 -61R
8.6 Whistlefield 15 39 25 58R
9.2MP11 7282 1½ 54R
10.2 “12 0172 0½ 59R/L
12.2 “14 34838 0R/122R
13.5 Glen Douglas 25 52 -56F
17.5 Arrochar&Tarbet 34/0 33 12/0 -53F/69R
8.0 Ardlui 15/0 13 50/0 -30R/66F
0.4 MP 28 142- 68R
1.4 “29 55 26/25 61R
3.4 “31 25 33½ 103F/103R
7.4 “35 7032 5½ 60R/423R
8.7 CRIANLARICH 20/0 19 47/0 -84R/66F
0.7 MP 37 145396 4F
4.7 “41 0152 3½ 60R/66R
5.0 Tyndrum 11/0 11 20/0 -66R
0.7 MP 42 235- 60R
1.7 “43 56 28½ 83R/63R
7.5 Bridge of Orchy14/0 14 30/0 -55F/77F
1.2 MP 50 31929 4R/200F
3.2 “52 22 44 240R/114R
5.2 “54 46 28½ 66R
7.2 “56 3523 1½ 81R
8.7 Gortan 16 29 -/36 84R/148F
15.6 Rannoch 27/0 27 12/0 -48F/60F
1.6 MP 66 517185 3R
7.3 Corrou r1 51 522- 140R
n/a =not available *=speed reduced by brakesTABLE 1:DUMBARTON-CORROUR
‘K2’2-6-0 ‘K4’2-6-0 ‘B1’4-6-0 ‘LM5’4-6-0 ‘BR5’4-6-0Loco Wt 64t08c 68t 08c 71t 03c 72t 02c 76t 00c
Adhesion Wt 53t18c 57t 18c 52t 10c 54t 05c 58t 01c
Tender 43t 02c 44t 04c 52t 00c 54t 13c 49t 03cCylinders (2) 20in (3) 18½in (2) 20in (2) 18½in (2) 19in
x26in x26in x26in x28in x28in
Boiler
Pressure 180l bpsi 200lb psi 225lb psi 225psi 225lb psi
CoupledWheel
Diameter 5ft8in 5ft2in 6ft2in 6ft0in 6ft2in
Tractiv eEffort23,400lb 36,600lb 26,880lb 25,455lb 26,120lbEvaporativeHtg
Surface 1629 .5sq ft 1,421.6sqft 1,676sqft 1,650sqft 1,650sqft
Superheater 305s qft310sqft 344sqft 348sqft 358sqft
GrateArea 24sqft 27.5sqft 27.9sqft 28.65sqft 28.7sqftCOMPARISON OF LOCODIMENSIONS