The Speed of a Greyhound - the Strength of a Boar
Converting an Ace Trains 9F to Finescale
Brian Beer - Gazette - May 2018 (Vol 20 No.7)
Having previously purchased an ACE TRAINs Britannia and converted the model for successful fine scale running, I
decided to buy a 9F from the company and carry out the same procedure.
ACE TRAINs locos are manufactured to run on coarse scale track and are fitted with appropriate wheels and running
gear. However, their diecast bodies and chassis are excellent scale models, with fine scale details and great
realism. The ACE 9F loco body is particularly good and accurate - a point that perhaps some other manufactures
might take note of. Its cab detail is threadbare, but this could be improved if the modeller so requires
it. When considering small deviations like this, the price tag of these superb models must be taken
into account and also the market for which they are intended.
Like the Britannia, I took a close look at the 9F and knew I could carry out a satisfactory conversion to run on
my 5ft radius curves.
I started by dismantling the whole locomotive to expose the bare chassis which is robustly nut
and bolted together, with a centrally mounted lead weight.
To increase realism the chassis was drilled in the correct positions (i.e. in front/in-between each of
the five driving axles) so that brake hangers or drop links could be fitted. This proved to be a more
difficult task than with the Britannia, due to the close proximity of the 9F driving wheel sets. The
brake shoes of necessity had to be plastic, to prevent electrical shorting on 2-rail track. The
shoes were purchased from Slaters and mounted on brass rods extending to each side of the chassis.
The five driving wheel axles had their coarse wheels replaced with Walsall cast iron fine scale
wheels drilled to accept ACE insulation bushes.
Photo 2. The floating brass rodding that allows the front brake shoes to traverse with the wheels
can be seen on the right of this picture. The unpainted frame spacer forms the bearing plate
for the front bogie springing.
The same arrangement was used on the Britannia conversion. This enables the ACE motor, gearbox
and drive arrangement to be retained, thus reducing cost.
The 9F’s tender wheel conversion is also a replication of the Britannia tender conversion. This
was described Gazette Volume 19, No 10, February 2016.
The connecting rods and associated valve gear were replaced with Premier Component rods,
which match the fine scale wheels and improve realism.
When negotiating the tight curves on my layout, it is necessary to allow the brake hanger and shoe
assembly freedom of movement in the lateral direction, matching that of the loco wheel sets. I
know this is not prototypical, but then most 7mm scale, gauge O locos of long wheelbase do not
have the luxury of running on 20ft radius curves and it is necessary to be practical if we are to enjoy
the hobby in our limited space homes.
The curvature problem has resulted in the fitting of a double tie rod structure allowing flexibility
with the ten coupled drivers. However, when the loco is on the track the brakes look realistic and she
will run successfully around 4ft 6in curves pulling a substantial load.
The pony truck on the loco front end of the ACE model is very basic and so I decided to modify it to
a fabricated open frame structure, as per the prototype. I carefully cut out the centre of the ACE
bent alloy truck and soldered brass angle strip along its outer edges to emulate the real 9F pony
truck frame.
To this I added reinforcing straps from the top of the axle box housing to the centre of the side
frames; this provides longitudinal stiffness as per the prototype. The ACE 90deg bent metal
trunnions made to take the single wheel set were then re-drilled to take brass 3/16 inch bore brass
bearings to suit a Slaters single wheel set of the correct scale size. The bogie was then stiffened by
soldering a 2mm thick by 8mm wide brass strip across the trunnions. The axle housing is now a
strong rigid frame structure, on top of which I’ve mounted a brass loco sprung buffer for the pony truck
vertical suspension. The sprung buffer head contacts on a matching 8×2 mm brass tie strip
across the loco chassis. A vertical lift of 3mm above the rail head, allows sufficient downward spring
pressure on the wheel set to maintain stable running without lifting the front driving wheels.
This new arrangement is more prototypical with the springing directly over the truck axle and not
adjacent to the radial pivot point as on the ACE original. (See photos 5 and 6).
The Riddles 9F pony truck suspension assembly
on the full size locomotive is complicated. It
incorporates both lateral and vertical suspension
springing, damping and inter linkage in a compact area located between the axle box housings. This
makes it difficult to accurately model in the
smaller scales.
On the real 9F this complex arrangement was prevent derailments that have been associated
with single axle bogies or pony truck designs in the
past.
Looking at the real full size beast, what a
locomotive it is! The magnificent achievements of
super-power, speed and smooth running speak for
themselves. Popular with all loco-men the design
was the last and arguably the most efficient and
successful of British Steam Motive power.
Likewise, my modified ACE 9F is the most
powerful, smooth running loco on my railway and
that’s using a Gaugemaster 12 volt DC controller,
not 20 volt for which the models are designed. The
motor and traction enable the loco to pull my 50
wagon mixed freight with ease. It will also pull my
8 coach MK1 brass coach set at express speeds
without slipping. I’m very impressed with its overall
performance and great value for money.
My next project is to modify their excellent
looking Jubilee locomotive.
Addendum
The ACE loco firebox is illuminated with a tungsten bulb fed off the rail voltage. I’ve modified my 9F with illumination provided by a more realistic flickering LED circuit fitted into the firebox. It looks good and if readers are interested, I will provide details in a future Gazette.
Photo 3. The finescale driving wheels, brake gear and the sprung buffer on the pony truck can be seen here.
Photo 4. Replacement coupling and connecting rods and valve gear are milled
nickel silver obtained from Premier Components.
Photo 5. This is the pony truck with its wagon
buffer springing arrangement and the diagonal brass strip stiffeners that were added as part of the conversion.
Photo 6.A front end view of the pony truck
Photo 7. The re-wheeled truck now in position on the loco
