the great Roco chassis disappointment
When Roco brought out their outside frame
chassis, I have to say that I was very excited. Here, at last was a basis
for ordinary mortals to have more realistic and sweet running locos. There
was a drawback that the gearbox protruded well behind the rear driver and
in some cases made adding a pony truck impossible. Nevertheless, overall,
this seemed to be a great advance for 4mm narrow gauge modelling.
The cost was high, but acceptable for a high
I quickly converted a chassis for my
'Russell' and even grafted on Backwoods valve gear. It worked like a
dream, smooth as silk, very slow speed....in fact, everything one could
Drunk with this success, I followed this up
with fitting one under our Alco and then two under our freelance Mallet.
All seemed well with the world, until about 18 months later, Russell began
to oscillate. Very slightly at first but this quickly developed into an
impossible roll. Smooth running was a thing of the past and it was clear
that something very serious had happened. A little later, the ALCO
developed a small oscillation followed by the Mallet. I realised that £400
had been wasted on buying four joke chassis and I was not best pleased.
It was time to send Russell to our loco
doctor. After four days of work, the chassis was sent back with a note
saying that as far as he was concerned, it was scrap.
Mallet 'River Avon' on two Roco chassis
: time of chassis build 1 week
Alco on Roco chassis :
time of chassis build 3 days
R.I.P. Russell on Roco chassis
: time of chassis build 10 days
A grand total of £400 and 20 hard working
days. This is what we believe happens to these chassis.
New Roco chassis
The steel axles run in slots in the die cast
chassis. They are held in place by a plastic keeper plate and the spring
pickups act on the flange tops. At first, the arrangement seems to work
very well indeed, but sadly, wear begins on the axles and chassis slot.
Once sideways play happens, things go from
bad to disastrous very quickly and the 'apple of your eye' turns into a
graveyard casualty very quickly indeed. Russell went first as the drive
wheel was operating scale Russell valve gear rather than the lightweight
plastic gear supplied. The other locos are, however, moving in the same
direction with standard Roco gear.
Many commercial locos are constructed in this
fashion, but not with outside gear. The axles on these chassis are
extended with a plastic moulding which includes the crank which clips into
the wheel. This passes through dummy outside frames. The result is
that the coupling rod is a long way outside the axle bearings and the
reciprocal motion of the connecting rod places much greater strain on the
As the axles have only point running in the
chassis slot, it is not long before wear begins.
I am sure that this chassis will give good
service to many layouts which do not demand continuous running over
distances, but if you expect your locos to run well for a long time,
perhaps it would be a good idea to consider other alternatives such as the
excellent and much cheaper Grafar class 08 chassis.
For me, the perfect chassis has bronze axle
boxes and is driven on all axles, which prevents excessive wear on
coupling rods and pins.