This is a model of a Doxford Marine Oil (Diesel) engine based on instructions that were
published in the 1931 edition of Meccano Book of New Models as "Doxford Type Internal
Combustion Engine." These engines were first developed by engineering company
William Doxford and Sons Ltd. of Sunderland in 1914 the last engine of this type was
built in 1980. They were used to mainly to power cargo ships and liners the engines
were powerful, low revving and could be huge some were the height of a three story
house. The Doxford engines had opposed pistons that is to say two in each cylinder so a
two cylinder engine would be the equivalent of a conventional four cylinder type. The
model is far from a scale model but does demonstrate well the principle features of the
Doxford engine, showing how the opposing pistons are linked to the single crankshaft.
There is also a third cylinder called a scavenger this pushes air through each cylinder
after each cycle of the engine to clean the cylinder of any burn debris. This was very
much needed as the fuel used was dirty heavy oil basically crude.
The model instructions made no mention of operating it with either a motor or by hand
operation, my version is hand operated with face plate and handle on the end of the
crankshaft. One of the complications was building the crankshaft using 16 p/n 62 cranks,
the alignment was difficult. The long rods connecting the upper opposing piston tended
to jam causing the cranks to slip out of true but patience prevailed. I solved this by giving
a tiny bit of slack, I undid the grub screws on the couplings holding the horizontal rod
connecting the two vertical rods and this did the trick. (no doubt the rods I used were not
perfectly straight). I have used 1970's yellow and zinc finish parts. At the time the plans
were published parts were dark red and green, my original thought was to used those
colours.You can see the engine working clicking on the YouTube link below.
You can find out about William Doxford and Sons by clicking this link.
Underside showing crankshaft
Page first published March 05 2024
Revised April 17 2024
Click on the images to see them larger