St.Albans and District Model Engineering Society

Crossley HD11 Oil Engine at Redbournbury Mill

This is the Crossley Oil Engine at Redbournbury Mill St.Albans.

It was built in Manchester in 1932 - quite recent for this type of engine. The owners of the mill bought it in 1995 in very poor condition. It had been lying outdoors in an enthusiast's garden for some 30 years since it was rescued from the scrap man at an Aldershot water pumping station. On arrival at Redbournbury it was very rusty and the piston was seized in the cylinder. A team of volunteers put in many hundreds of hours of work over eight months in 1996 dismantling the entire engine, freeing the seized piston, de-rusting and renovating all the parts, painting it and reassembling it. Eventually it was restored to full working order to run for the first time in over 30 years on 4th September, 1996.

A further two years of work were needed before the engine was finally connected up to drive the mill, which has been achieved electrically.
The engine drives a substantial 240 V a.c. electric generator which provides more than enough power for the mill, including lighting and a large electric motor that can drive all the mill machinery if there is
not enough water in the river Ver to run the mill from the overshot water wheel.

The engine specification is as follows:
Crossley HD11 four stroke oil engine, built 1932.
Rated at 55 b.h.p. @ 270 r.p.m. running on diesel fuel.
Stroke 20", bore 11", capacity 31 litres. Flywheel 7'2" diameter. Started by compressed air @300p.s.i. (the engine is manually set up just past top dead centre on firing stroke before admitting compressed air to the cylinder)
Total engine weight is approx 4.5tonnes of which the flywheel is over 2 tonnes.
Speed is controlled by a governor which regulates the amount of fuel injected into the cylinder on each stroke.

A video of the engine starting and running can be seen on YouTube

More information and photos can be found on the Redbournbury Mill website at

Roger Stephen. 23rd April 2023