Tag Archives: Sims Compound Engine

Jope’s Shaft Pumping engine House

Christmas is well gone and past, and so this series of posts on South Caradon mine has restarted.  Winter brought with it one of those amazing clear air days last weekend, no mist, no drizzle no rain, just pure blue light. And so, armed with a camera and Christmas cake and set off to Caradon hill to update some of my photographs of the mine.  

South Caradon Mine’s best preserved engine house

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Jope's engine house in 2018

Jope’s Shaft pumping engine house is the best preserved on South Caradon Mine, with its ivy clad engine house and chimney still standing to full height. It is fascinating engine house, packed with features.

Jope’s shaft  is located on the south western corner of Caradon Hill , overlooking the entrance to Seaton Coombe.

It possibly housed one of the few Sims compound engines built in Cornwall the shaft was also historically important as the site of the last man engine to be built.

The engine

Jope's pumping engine house looking through the cylinder arch

The raised plug doorway is shown on the far side of the building.

This is no ordinary engine house. This is an engine house with it has its plug door located at a level higher than normal instead of being on the same floor as the cylinder bed it hangs precariously one level up. Why this should be seems to a subject of disagreement, with two conflicting theories.

The engine transfer theory

This 60″ engine was built in New for South Garras lead mine in 1855 at Landeryou’s shaft. That mine was not a success, and the engine was sold to South Caradon in 1862.

Click here to see the location of South Garras on OS Maps online>

Kenneth Brown in his excellent exploring Cornish Mines book (vol 2) explains that sometimes plug doorways were placed in a raised position  when the cylinder was set down into loading to reduce the height of the engine house. This arrangement resulted in a raised engine driver’s position.

Click here to find the book on Amazon>

This was not case at Jope’s but may have been the case at South Gerras.

The Sims engine theory

This is the explanation given by Adam Sharpe in the Minion’s study (cau). The study states that the engine was a Sim’s compound, a design of engine that William West, South Caradon’s engineer, was an enthusiast of.

Sims compound
This was  single acting Cornish engine in which the smaller steam cylinder was mounted above a larger low pressure cylinder, with the pistons having a common rod.
The engine was devised by James Sims in the 1840s. The duty was rarely more than a conventional engine, and its complexity and difficult maintenance meant that most Sims compound engines had short lives.

Click here for more information about William West and Sims compounds>

Which theory is correct?

When it comes to Cornish engines Kenneth Brown was rarely wrong. This is a pity in this case, for Sims engine at South Caradon would be a wonderful example of Wests’s Sim’s compound installations. If you have more information, or comments, or views on the engine please pass me a message to share on this site.

Features to be found

This is a engine house rich in features.

The interior

The bedstone of Jope's engine

The cylinder bedstone

The three piece granite Bedstone is still in place within the engine house, the cylinder holding down bolt holes clearly visible. Beyond the stones the cockpit/cataract pit is still open (the underfloor space were the valve timing mechanism was located). The eduction pipe is opening can be seen at the base of the bob wall, and on the western wing wall the opening for the steam pipe down to the boiler house is obvious.

The exterior

To the west of the engine house is clearly defined remains of the Boilerhouse, a house which has evidence of a third boiler was added later in the engine’s life.

Jopes engine boiler house

The Chimney putlog holes

The stack at Jope’s has one of the best examples of putlog holes in Cornwall. These holesPutlog holes in Jope's stack in the side of the chimney are the remains of a crude form of scaffolding used to build the structure. Planks were inserted in the holes as the chimney rose skywards to give the masons safe footholds.

More features

Many other fascinating remains surround the engine house, but these I will leave to a later post when I resurrect the map of the Jope’s shaft area.

 



Important note


This blog is written to enhance the enjoyment of those exploring Cornwall’s amazing landscape and history. It is not intended as a guide for walkers. If you are exploring industrial landscapes in Cornwall, please check the rights of way with the latest Ordnance Survey map, and take great care of yourself  and anyone else accompanying you.   Despite of all the due care and diligence shown by landowners, any open access ground can be dangerous to those not  ensuring aware of the risks around them. So look after yourself.

 

 

 

 

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The James Sims Compound Engine- What did it look like?

Sims

James Sim’s had several connections with William West, and their relationship was a mixed one. As seen in an earlier post, he was one of the most vocal of the Austen’s Engine trial critics.   He would became related to West through marriage, when he William married his sister, Grace Sims.

The West-Sims business relationship would in time evolve from  bitter rivalry into a working partnership.  In 1843 the Sims family granted West the licence to build the Sims compound engine, and West installed several large engines of this design in Devon and Cornwall.

Jame’s engine was developed in the late 1830s. It used two cylinders one above the other; the smaller higher pressure cylinder sat on top of the larger lower pressure cylinder. The design was attempt to reduce the ‘kick’ being induced by using higher pressure steam. Unfortunately it required a taller, and therefore more expensive engine house, in addition to being difficult to maintain as a result of steam packing gland located deep within the engine, between the two cylinders. It was not a design that was widely adopted, although it did form the basis of the huge dutch engines at Cruiquis.

I have been hunting the web for a good picture of the design, as SimsCoverCloseso far this is the best I can discover. A cover of a book for sale at Plough books.  Feel free to comment if you have stumbled across others. The Cruquis museum on their excellent website has a diagram and description of its operation.

This is the best I have managed with the book cover, not a good image  I admit. It does show well the overall layout however, and more importantly, the impact its design had on the engine house. Having the high pressure cylinder stacked on top would have demanded a significantly taller building.


If you do know of some better images of this type of compound engines please post a message, I am sure there must be some better ones out there. Meanwhile the preparation for the Luxulyan valley talk continues….jm

 

 

 

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