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Bark Engine History
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Richard Carlstedt All rights reserved.
Model Steam Engines

Bark Mills 

Bark mills were used for grinding or cutting the roots, branches, and/or barks of different species of trees to form a fine powder (tanbark) suitable for the operations of the tanner in the preparation for making leather for clothes, boots, furniture, etc.  They work on the same principle as a coffee grinder.  The powdered wood more quickly yields up the tannin required for the tanning process.   The dried bark was often stored in bark houses.  This particular design was patented in England in 1797 by James Weldon.

 

Engine

Steam engines using the hypocycloidal design did not last very long. The biggest reason probably was that industry was demanding bigger and more powerful engines and the hypocycloidal design was very limited in that regard.  It could not be scaled up very well and therefore could not deliver the power required by industry. Most (if not all) engines that were built were less than about 8-10 hp.

 

Hypocycloidal motion

Hypocycloidal motion is based on the known mathematical concept in which an internal planetary gear that is half the size of the ring gear will yield straight-line motion along the pitch diameter while the internal planetary gear travels around the circumference of the ring gear.  This allowed an ingenious way to convert the straight-line motion of the piston to the necessary rotary motion of the crankshaft.  Matthew Murray patented the application of the hypocycloidal motion to an engine in 1802.  This was most likely done to circumnavigate the parallel motion patent in force by James Watt.

 

Fenton, Murray & Wood 

In  1797, James Fenton, Matthew Murray (inventor of the Bark Engine)  and David Wood formed a business partnership and opened a foundry in Water-Lane, Leeds, England.  Initially they built machine tools and stationary steam engines.  The organization rapidly distinguished itself for the high quality of their workmanship, and attracted the attention of Boulton and Watt, who purchased land surrounding the workshop so as to prevent the firm from expanding.  Nevertheless the company became serious rivals to Boulton and Watt and by the beginning of the 19th century, was challenging them for the position as the leading producer of steam engines in Britain.

A Brief History Of The Bark Engine - by Scott Ruesch
Farey Plate drawing of a Bark Mill Engine by John Farey Jr. (circa. 1825)