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What is a Donkey Engine?

A donkey engine is a small, auxiliary steam engine, originally used in the logging industry for tasks like hauling logs and powering winches. Despite its modest size, it played a crucial role in early industrialization, showcasing the ingenuity of engineering. Curious about how this vintage powerhouse influenced modern machinery? Let's delve deeper into the evolution of mechanical muscle.
Harriette Halepis
Harriette Halepis

A donkey engine, or steam donkey, is a type of mechanical pulley system that was often used within the logging industry during the 1800s. Donkey engines were often steam powered, which made them highly efficient for transporting wood. In addition to being a popular fixture within the logging industry, these engines were also used for mining applications and maritime activities.

John Dolbeer is credited with inventing the donkey engine in 1881. The invention of the internal combustion engine during the mid-1850s largely eliminated the need for the steam powered donkey engine, but this logging machine was put to good use prior to the 1850s. Not only was this machine relatively easy to operate, it was also highly efficient at transporting large logs.

Man with hands on his hips
Man with hands on his hips

With the help of a work horse, a donkey engine cable was dragged into a wooded area where trees had recently been cut. Then, this cable was securely attached to a large log destined for a wood mill. When the cable was securely attached, a donkey engine operator would open the machine's regulator. This allowed the machine to act like a mechanical pulley by slowly pulling the log towards the machine. Once the log had reached the machine, the log was then loaded onto another vehicle. Eventually, all of the logs that were pulled out of the forest were sent to mills via rail.

Since donkey engines were large in size, and quite heavy, moving this type of machine proved to be a problem. Eventually, loggers learned that a donkey engine could move all by itself if the engine's cable was attached to a tree. By securing an engine's cable to a tree, the donkey engine would simply inch itself closer to the tree. Thus, the machine could be moved without a lot of manpower.

As sophisticated logging machines were created, the donkey engine was largely abandoned. In fact, many of these engines can still be found in forests all over the world. Since the machines were hard to move, even when the tree-pulling method was employed, many logging companies simply left donkey engines to waste away rather than remove them from a forest.

Some of these engines are presently on display in museums across the globe, though most of them have never been recovered. The modern logging industry has no use for donkey engines, since these engines are not as effective as modern machines. However, without the invention of the steam donkey, loggers who existed during the 1880s would have had a much harder life.

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Discussion Comments


@jmc88 - You are right. I also find it very interesting that the people who operated these so called donkey engines would just leave them out in the woods.

I highly doubt there are very many left, still sitting in the woods, as I imagine people have either moved them already or taken them away to be put in a museum or scrapped for parts, but I would like to know where the nearest place is I can view one of these interesting machines out in the wilderness.


@kentuckycat - Right you are. I do not believe that there was any other type of machine used for this purpose before the donkey engine and that the only things they would do is either pull the logs with either people or horses, or simply let the river do the work for them.

What I find really interesting is that when the donkey engine was determined to be obsolete they were simply left in the forest to stay for years and years.

I am betting that the people that would eventually own the land would not be able to move these machines, because of their immense size, and they simply sat there until technology had advanced enough in the field of heavy machinery that a machine could be used to move it.


@stl156 - I do not know as far as if there was anything before the 1700's, but to my knowledge this steam engine is the first type of machine like this that was used to move logs.

To be totally honest I find this machine to be quite interesting as it was new to people back then and definitely helped their efficiency exponentially in regards to how many logs they were able to move in a day.

I think that it is so interesting because it was such a radical change from the times in the past when horses and people had to be used to simply move these logs across valleys and the landscape.

I understand now why they utilized rivers very often to move logs because it was probably the easiest way to get these logs from one place to another before this engine came along.


I have to say that I was interested in this article. I find it interesting that there is such a thing as a donkey steam engine and that it was the original precursor to fuel engines.

I just find it interesting that there were in fact machines that could be used for heavy duty purposes, such as moving logs, back in the early 1800's well before big heavy machinery, like we see today, was available.

I think it would be interesting to see if there were even other steam powered machines that had been invented well before the donkey engine and if there was even something around just for log moving.

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