THE RAILWAY GAZETTE, July 21, 1939 BEYER, PEACOCK
& CO. LTD., LOCOMOTIVE ENGINEERS, MANCHESTER
Editorial Note from "The Railway Gazette" July 21,
1939
The First 4-8-4 + 4-8-4 Locomotive
The first Beyer-Garratt locomotive to be fitted
with an inside four-wheel bogie, a 4-6-4 + 4-6-4, was described in our issue
of February 26, 1937. Another example of the inclusion of the four-wheel
bogie on the inside of the engine units of a Garratt engine is the subject
of an article this week. The wheel arrangement in this case is 4-8-4 +
4-8-4, and, incidentally, this is the first time such a wheel arrangement
has been embodied in any steam locomotive. The engines, of which six have
been built and another six are under construction, are for the Kenya &
Uganda Railways. The huge boiler and extended wheel arrangement that this
system of articulation permits is noteworthy, and the fact that the engine
is to operate on a 50-lb. rail, has a maximum axleload of less than 12 tons,
and can negotiate a 275-ft. radius curve, yet weighs 186 tons, makes this
locomotive a conspicuous example, of the designing capacity and in genuity
of the British locomotive manufacturer. The Kenya & Uganda Railways have
used Garratt engines for many years, and before long the 879 miles of main
line will be operated almost entirely by this type of engine, which is an
indication of the state of reliability and availability it has attained, and
how it can give to a railway restricted by a narrow gauge and light rail the
carrying capacity of a standard-gauge railway.
NEW 4-8-4 + 4-8-4 METRE-GAUGE BEYER-GARRATT
LOCOMOTIVES, KENYA & UGANDA RAILWAYS
These engines are the first i n the world to have
this wheel arrangement and the largest 50-lb. rail locomotives ever built
One of the exclusive characteristics of the
Garratt principle of articulation is the ability to accommodate on each
engine unit any wheel diameter or wheel arrangement which can be applied in
the ordinary type of engine, and the new design of Beyer-Garratt locomotive
we now describe and illustrate is an excellent example of the way in which
so extended a wheel arrangement as
4-8-4 + 4-8-4 can be incorporated. The order,
comprising six locomotives of this type, has recently been completed by
Beyer, Peacock & Co. Ltd. at Gorton, Manchester, and shipped, and some are
already in service. An order for a further six has already been placed. This
new type has been designed by Beyer, Peacock & Co. Ltd. to the detailed
specification of the Chief Mechanical Engineer, Mr. K. C. Strahan (now
retired), and the subsequent requirements of Mr. H. B. Stoyle, present Chief
Mechanical Engineer and previously Locomotive Running Superintendent of the
railway. The Kenya & Uganda Railways administration has been a user of
Garratt locomotives for several years, the 36 engines of this type operating
about two-thirds of the total main-line traffic. Perhaps nowhere in the
world have Garratt engines been worked more intensively, the mileages
obtained being a record for a narrow-gauge line of this kind. The new design
not only embodies the makers' improvements culled from the experience of
Garratts in service in various parts of the world, but includes various
modifications and alterations suggested by the railway, based on its long
experience, which combine to make these new engines particularly interesting
and outstanding examples of the present-day Garratt. They have been built
under the supervision and inspection of the Crown Agents for the Colonies.
Before passing on to a detailed description of these engines, it is
therefore interesting to observe the extraordinary size of the locomotive, a
point with which we were particularly struck when we inspected one of the
type, considering the restrictive conditions of a metre-gauge and 50-lb.
rail. On this light rail-half the weight of the rail in Great Britain-and on
a gauge 1 ft. 5 1/8 in. less with more difficult grade and curvature
conditions, the tractive effort of the engine is equal to the biggest
passenger engines in Great Britain while the boiler is practically equal in
horsepower, having a similar size grate and an even larger barrel diameter
despite the total height to chimney top from rail level of 12 ft. 5 1/2 in.,
which is nearly a foot lower than the highest British dimension. The
locomotive further weighs roughly 20 tons more than the largest British
types, the width over the running board is 9 ft. 6 in., and the footplate
area is considerably larger than that of many standard gauge engines. The
design embodies many interesting features, some of which constitute a
fundamental departure from the practice originally introduced by Beyer,
Peacock & Co. Ltd. The two principal differences, apart from the wheel
arrangement, are the inversion of the pivot centres, the male portion being
on the engine unit instead of on the boiler cradle, and the alteration of
the valve gear to bring the quadrant block of the links of each engine unit
to the same position for whichever direction the engine is running.
This is the first time that the 4-8-4 + 4-8-4
wheel arrangement has been adopted; it is designed for 573-ft. radius curves
on the main line and 275-ft curves in sidings. It has naturally brought
fresh problems for solution such as the distribution of weight in relation
to the strength of frames, alteration of the relative position of the pivot
centres, clearances necessary for the longer units and method of
compensation, &c., while the inside dimension between the unit bar frames of
only 2 ft. in this case is an ever present difficulty to the designer of
narrow-gauge engines. Further, it was specified that the engines were to be
designed to facilitate conversion
to 3 ft. 6 in. gauge with the minimum of
alteration; thus the cylinders and rods and motion ape centred for the wider
gauge, a wider wheel centre providing for the shifting of the tyres
outwards. The engine has also been designed to take care of the possible
conversion of the Westinghouse brake to vacuum, when the gauge is altered,
and also for the ultimate introduction of automatic couplers. Despite these
features, however, a far greater measure of accessibility has been obtained
throughout the locomotive than hitherto. Previous Beyer-Garratt locomotives
on the Kenya & Uganda Railways have been of the 4-8-2 + 2-8-4 wheel
arrangement, with a coupled wheel diameter of 3 ft. 7 in. in keeping with an
existing wheel on a standard ordinary engine. With the gradual speeding up
of traffic and the extended use of Garratt engines over the whole main line,
where the grades are easier, it was decided to increase the size of wheel in
the present engines to 4 ft. 6 in., thus reducing the revolutions per mile
by 20 per cent. with a consequently better balanced and freer running
engine, resulting in considerably reduced maintenance. The introduction of
the inside four-wheeled bogies has permitted a larger boiler for continued
maximum output and also enabled larger coal and water supplies to be
carried. The tracking properties of the engine have also been considerably
improved by the guiding and protective effect of the bogies fore and aft, of
the coupled system, which should result in reduced wear of rails and
flanges. Existing Garratt engines, which work passenger and goods trains,
are operated mainly by two sets of engine men, either Europeans or Asians,
and African firemen, one set resting in a " caboose " and changing over
every 8 hours. This system has been in vogue for some years and round trips
of 660 miles-Nairobi-Mombassa- Nairobi are run daily. With the new engines
it is contemplated to run from Nairobi to Kampala and back, a round trip of
1,100 miles, and to this end various features have been introduced to lessen
the enginemen's responsibility and work on the road, such as roller bearings
on all bogie wheels and an extensive use of grease lubrication as detailed
later.
General Design
From the various illustrations a good idea can be
obtained of the general layout of the locomotive. The boiler rests in the
usual plate type of cradle frame, lengthened to take care of the new wheel
arrangement; the plates are stayed together at each end by a steel casting
of massive proportions, carrying the top portion of the pivot centre
arrangement. Adjacent castings form a saddle to which the boiler is stayed,
the firebox being supported by expansion brackets riveted to the wrapper
sheet, and resting on the top of the cradle frame. The cradle frame is also
suitably stayed along its length. The engine unit frames are of the bar type
4 in. thick, 35 ft. long, and are made from rolled steel slabs of
Appleby-Frodingham Steel Company's manufacture. These are bound together by
various steel castings, the principal ones including the drag box at the
front end and a large casting incorporating the male portion of the pivot.
Further, the cylinders, made in two castings, are bolted together on the
centre line, giving additional rigidity to the whole chassis. The inside
extremities of the bar frames have also substantial steel castings to carry
the 20 odd tons with which the bogies are loaded. The pivot arrangement as
already mentioned, has been turned upside down compared with previous
practice, access of coal or smokebox ash and dirt generally being thus
prevented.
The centres are provided with re- newable seatings
and a brass liner, while the bottom
centre is fitted with a renewable ring. The design
embodies the Beyer, Peacock patent adjustable arrangement for taking up
wear; the adjustment, which can be made from the outside of the engine, is
by means of a wedge acting on a segment. The side bearers are the maker's
latest type consisting of grease-lubricated rollers.
The following are the principal dimensions :
- Cylinders (4), dia
16 in.
stroke
26 in.
Piston valves, dia
9 in.
max. travel
5 in.
Coupled wheels, dia.
4 ft. 6 in.
Evaporative heating surface,
tubes
2,015 sq. ft.
firebox
251 sq. ft . (including two syphons and two arch tubes)
Total
2,266 sq. ft.
Superheater (inside)
484 sq. ft.
Combined
2,750 sq. ft.
Grate are .
48.5 sq. ft .
Boilerpress
220 lb./sq. in.
Coal capacity
12 tons
Water capacity
6,000 gal.
Tractive effort
(at 75 per cent.b.p.)
40,670 lb.
(at 78 per cent. b.p.)
46,090 lb.
Weight of locomotive in working order 186 tons
Boiler
As will be seen, the boiler is of quite
exceptional size for the metre gauge, the outside diameter of the barrel
being as large as
6 ft. 9 1/2 in. and the grate area 48.5 sq. ft.
The pressure is 220 lb. per sq. in. The boiler barrel is made up of two
sheets of Park Gate Iron & Steel Company's manufacture; the smokebox
tubeplate is of the drumhead type. The boiler is fitted with a scum cock and
blow-down cock operated from the side of the engine, and a main stop valve
to the dry pipe is fitted in the dome. The firebox, it will be noted, is of,
the round-top type as against the Belpaire on previous Garratt engines
supplied to this railway, while the inner firebox is of steel as against
copper on previous engines. This inner firebox, which is fitted with two
Nicholson thermic syphons and two arch tubes, is made of Colville's special
Double Crown firebox steel and is completely welded throughout. The roof
stays are of the radial type with three rows of flexible stays at the front
end. Flexible stays are also provided in the breaking areas on the sides are
also on the two top rows. The smokebox is of large capacity and fitted with
a hot water ash ejector. Jumper top blastpipes have been fitted for
experimental purposes but plain caps have also been supplied. The
superheater is of the Superheater Company's manufacture, fitted with the
multiple valve regulator positioned between the superheater and the
cylinders, the superheater elements, header, and internal steam pipe thus
being continually under full boiler pressure while also affording instant
and fine regulation of the steam supply to the cylinders. There are 38 flue
tubes, 5 1/4 in. outside diameter, with superheater elements l 3/8 in.
outside diameter, 10 w.g. thick, having Melesco forged return bends and ball
joint attachment to the header. The number of small tubes is 220 of 1 7/8
in. outside dia- meter; all the tubes are of Howell's Aquacidox steel, The
barrel is clothed, as are also firebox and cylinders with J. W. Roberts's
Limpet asbestos mattresses. The boiler is fed by a No. 12 Gresham & Craven
live steam injector placed beneath the cab, and also by a Davies & Metcalfe
exhaust steam injector No, 11, both delivering into the barel by double
top-feed clackboxes. The exhaust steam injector has a capacity of 3,000 gal.
per hr. and is controlled by a lever in the cab with a graduated scale by
the regulation of which the fireman can maintain a constant feed to the
boiler to ensure the maximum quantity of exhaust steam being utilised. The
safety valves consist of three 24-in. dia. of the Ross muffled pop type. The
firegrate arrangement consists of rocking firebars in two sections, each
having a drop grate at the front, the firebars being operated by steam and
hand. The control levers are marked for the up and level positions, the
cylinder for each section of firebars being placed on each side of the
boiler cradle frame. These can be seen in the illustrations. The ashpan is
similar to the latest selfcleaning type fitted to South African
Beyer-Garratt engines, discharging between the rails. It is fitted with a
front and back damper and side doors and slides, all operated from the cab.
Cylinders and Valve Gear
The cylinders, of cast iron, have cast-iron
pistons fitted with two narrow rings. The piston valves, of the trunk type,
are 9 in. in diameter and fitted with four narrow rings. The valves,
actuated by Walschaerts gear, have a travel of 5 in. The links are of the
built-up box type with the reversing shaft fixed behind the link. Reference
has already been made to the alteration in this design from the usual
practice of combining the valve gears of the two engines. Previously one
engine was always in back gear, continuous running thus being done with the
quadrant block in the top section of the link. This, however, had the
advantage of placing the valve gears in balance as regards their control,
and a reversal of motion has thus had to be introduced to bring both engines
into the same gear position. This has necessitated the introduction of a
balance-weight which can be clearly seen in the close-up view of the front
engine unit. The valve gear is controlled by steam reversing gear with an
oil cataract locking cylinder similar to those already fitted to hundreds of
Garratt engines. The crosshead, of cast steel, is of the Laird type.
Lubrication to the slidebars is by a three-feed oil box going to the top and
bottom bars; the lubrication being, so to speak, internal, the ingress of
dust and foreign matter is prevented by the fitting of oil pads at the end
of the slipper and on the crosshead to protect the sides of the bottom bar.
The slippers are of cast iron with white-metal lining. Britimp metallic
packing is arranged for the piston rods. Attention may be drawn to the
layout of the valve gear generally, such as the length of the eccentric rod,
which is fitted with S.K.F. spherical roller bearings. The connecting rod is
also of considerable length, being 12 ft. 6 in. long. The big end is fitted
with a floating bush for grease lubrication referred to later under this
heading. Coasting is provided for by the fitting of by-pass valves and air
relief valves except in the case of the sixth engine, where the by-pass
valves arc blanked off and replaced by a new automatic drifting appliance
manufactured by J. Stone & Co. Ltd., which has already been in experimental
use in Kenya with very satisfactory results (see illustration). This
equipment consists of a double-acting vacuum pump driven off the locomotive
motion, controlling a steam shut-down and steam pressure reducing valve for
regulating the supply of drifting steam to the cylinders. The purpose of
this device is to render unnecessary the use of by-pass and air drifting
valves by maintaining a controlled supply of low pressure steam to the
locomotive cylinders when the locomotive is in motion and the regulator is
closed. When the locomotive stops the vacuum pump ceases to function, so
shutting off the supply of steam, any steam already in the steam chests (or
leakage of steam) being exhausted to the atmosphere. The main feature is,
therefore, to provide an automatic by-pass for the locomotive regulator
controlled by the movement of the locomotive and the pressure existing in
the cylinders.
Engine Unit Details
Attention is here directed to the close up illustration showing the front
engine unit, which is generally similar to the hind engine unit. As regards
the coupled wheelbase, the leading wheel has a flangeless tyre 5 3/4 in.
wide, thus reducing the rigid wheelbase to 10 ft. The four-wheel bogies are
identical except for the difference in the wheel-base, the outside bogies
having 6-ft. 2-in. centres as against 5-ft. 3-in. centres on the inner.
They are of the bar framed type with swan-neck
compensating beams, the suspension being two point with side control. All
bogie journals are fitted with Timken roller-bearing axle- boxes, and the
horn cheeks are lubricated from an adjacent oil box. The wheel centres, cast
at Beyer, Peacock & Co.'s steel foundry, have tyres of C.P. brand, secured
by Gibson rings, supplied by the United Steel Companies Ltd., and axles of
Taylor Bros. manufacture. Springs are arranged above the axleboxes, and
compensation is in two groups, namely, the outer coupled and intermediate
wheels in one group and the driving, inner coupled, and inner bogie in the
second group. The coupled axleboxes, designed for grease lubrication, are of
steel, and have brass bearings pressed into the axleboxes with a lip on the
hub side which bears against a cast iron wearing plate, studded on to the
hub.
The axleboxes also have side liners of gunmetal,
secured by cheesehead mild-steel set screws in accordance with the latest
Kenya & Uganda Railways practice. The brake gear is of the Westinghouse type
operating on the train and locomotive. Two 10-in. x 10 5/8 in. air
compressors, type KL2, are placed on the left-hand side of the boiler unit
at the smokebox, one 15-in. x 6 1/4-in. brake cylinder type " V " on each
engine unit. The footplate fitting consists of a No. 4 driver's brake valve
with a C.6A feed valve. As the engine is intended to run mainly chimney
first, the brake blocks are arranged behind the coupled wheels in both
units. A hand brake is fitted, operating on the hind engine only. Sand gear
of the Lambert type is also arranged particularly for forward running, the
application being to the leading coupled wheels of the front and hind units
and behind the coupled wheels of the hind unit only for backward running,
there being thus two sand boxes on the front unit and four on the hind. The
tanks and bunker, it will be noted, have snap-head rivets, the water tanks
having no bolt holes in the water space. Incidentally, the tanks and bunker
are more strongly built than in the previous engines, and more efficiently
baffled. At the end of the tanks boxes are located for housing three screw
jacks. Under this heading mention may be made of certain improvements to the
steam pipe layout; all joints are considerably stronger and of the
double-cone type. The main steam pipe to the hind engine runs along the
outside of the boiler cradle frame, passing under the footplate from which
it is insulated and thence by a generous curve h between the unit frames. A
double-expansion gland is provided, with lubricators located below the oil
cylinder of the steam reversing gear.
Lubrication
Lubrication to the cylinders is provided for by two Wakefield Eureka
lubricators, type " D," one a five-feed and the other a four-feed. The
five-feed lubricator lubricates the four cylinder barrels and the
Westinghouse pump. The four-feed lubricator lubricates each steamchest. The
exacting service which these locomotives are required to perform consequent
on the heavy gradients and length of run has necessitated special attention
being given to the question of lubrication, and at the same time lessening
the driver's work, and to this end the Ajax system of hard and soft grease
lubrication as supplied by Whitelegg & Rogers Limited has been applied to
the axleboxes, valve gear, brake and spring rigging. The Ajax lubricators
fitted to the boxes of the coupled wheels contain pads of hard grease which
provide lubrication for 20-30,000 miles, during which time no attention is
required by the engine crew. Monthly inspection is performed by the shed
staff. The hubs are also lubricated by grease. One application of soft
grease to the valve gear is considered sufficient for 2-300 miles, depending
on conditions, and the other parts of the engine are greased every 4-5,000
miles. When it is remembered that round trips of as much as 660 miles are
already being run, and up to 1,100 miles are contemplated, the importance of
a troublefree system of lubrication devoid of attention to trimmings, &c.,
becomes evident. A four-feed Wakefield mechanical lubricator, one on each
engine unit driven off the link, supplies oil to the ball-joints and pivot
centres.
Cab and Footplate
Reference has already been made to the large cab area, particularly for the
metre gauge. As extremes of cold and heat are encountered the cab has been
designed so that it can be entirely closed in or opened to provide the
maximum of air. The spectacle windows have been made as large as possible,
the side windows being fitted with double sliding louvres and removable
elbow rests. Cushioned collapsible seats for the engine crew are also
provided and an additional two seats on the back plate of the cab for
inspectors. Side doors are also fitted made in two parts to enable the top
half to be opened separately. The coal bunker is so designed as to provide a
large opening when required either for ventilation or access of enginemen to
the bunker. At the same time it has an arrangement of doors which enables
the back of the cab to be completely closed or to leave just the required
opening for firing. The firehole is fitted with an Ajax patent automatic
firedoor operated with compressed air by the action of the fireman's foot on
a pedal or by a hand lever. A coal watering pipe and ashpan drencher are
provided on the fireman's side. A fire-screen is fitted to protect, the
driver's legs. The regulator handle is of the type usual for the
multiple-valve regulator, and an extra handle is provided on the fireman's
side. Steam for the various fittings is obtained from a turret located on
the top of the boiler outside the cab, the various operating handles having
their functions clearly marked, as are also all control levers on the floor.
Electric lighting equipment is of J. Stone & Co. Ltd. manufacture, of that,
firm's LBB 32-volt type. The electric headlights in this case are being
supplied and fitted abroad from stock by the railway. The cab installa- tion
comprises lights behind the lubricators, a light to the gauge glasses, and a
screened light in the cab roof. All six locomotives are provided with
Stone-Deuta speed indicators, manufactured by J. Stone & Co. Ltd. Five of
the engines are fitted with the electrical type, indicating speed only, and
having the drive to the alternator taken from a pulley bolted to the face of
the rear bogie wheel under the cab, this driving the alternator or
transmitter by a coiled wire belt, the transmitter being bolted to a
carrying bracket off the bogie equalising beam. From the transmitter the
electric flex is led through flexible tubing and conduit to the speed
indicator in the cab. The other locomotive is fitted with a recording
instrument of the electro-magnetic type with mechanical drive. The water
gauges are of the Klinger reflex type A chime whistle is located on the
slope on the side of the smokebox and operated by steam from the cab. The
steam reversing lever, Westinghouse brake driver's valve, and the regulator,
&c., have been carefully positioned for comfortable working from the
driver's seat. The engines, which are numbered 77 to 82, have been named
after various districts and Government posts in Kenya and Uganda, as follow:
1939
77 Mengo, BP 6905
78 Teso, BP 6906
79 Uasin Gishu, BP 6907
80 Narok, BP 6908
81 Marakwet, BP 6909
82 Wajir, BP 6910
1940
83 Chua, BP 6970
84 Gulu, BP 6971
85 Lango, BP 6972
86 Budama, BP 6973
87 Karamoja, BP 6974/1940
88 Kigezi, BP 6975
