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Interesting items

 Lubricators

wp9b572fa5_06The ornate brass objects on the cylinder covers are manually operated cylinder lubricators. They feed oil to the steam side of the piston. In their base is a valve. On the No.1 Engine, this valve is held closed by the spherical weight on the end of the arm. On the No.2 Engine, the valve is of the rotary type. The cylinders are oiled twice per day when the engines are running.

In use, approximately 250 ml (½ pint) of oil is placed in the lubricator cup. On the upstroke (when there is a vacuum on the steam side of the piston), the operator opens the valve, which sucks the oil into the cylinder. The operator then closes the valve before the upstroke is complete. Several strokes may be needed to inject all of the oil. If the operator get his timing wrong, and has the valve open on the down stroke, then the steam pressure blows the oil out of the cup and over anything unfortunate enough to be near (i.e. at least the operator!). With ordinary lubricant, this would, to say the least, be unfortunate, but the oil used in this case is steam oil, a very viscous, sticky substance difficult to remove from skin or hair!   

Honey Street Clock

The Honey Street Clock is situated on the wall of the Boiler House. It was rescued from the demolished clock tower of Honey Street Wharf, next door to the boat yard of Robbins Lane and Pinnegar, one of the principle builders of boats for the Kennet and Avon Canal. The clock tower was a wooden structure consisting of ground and first floors with the clock loft above and a large iron weather vane on top.

The clock itself was said to have come to the boat yard from a church in Bath, which had burned down in about 1854. It had two faces, and was notoriously difficult to maintain and keep working. This is not surprising, as many of the parts from which it was made were improvised from farm machinery. For example, some of the wheels, together with the winding mechanism, are said to have come from a disused mangle grinder. Despite this,  provided that it was carefully tended by someone who understood its idiosyncrasies, it  performed reasonably well. However it did have its moments ; on one Sunday morning it was said to have struck continually 50 times, much to the local residents’ exasperation!  The clock is still in operation, carefully tended by the volunteers, although its timekeeping can be a little variable. 

Tottenham House Pump

Wilton Water, Crofton’s principle water source, was built on land owned by the Marquis of Ailesbury. Part of the deal in obtaining this water source, was that Crofton would provide Tottenham House, the Marquis’s splendid mansion; some 2 km (1¼ miles) away, with a supply of fresh water. To this end, a pump was installed on each engine. The pump on the No. 2 engine no longer exists, but the one on the No.1 engine (1812 Boulton and Watt) is still in working order, although it no longer supplies water to Tottenham House. However, the pump still serves a useful purpose, in that it supplies priming water for the No.2 pump which is notoriously difficult to prime on its own. Hence the running schedule which calls for an initial half hour run from No.1 before No.2 is ‘given its head’.  

Winter Maintenance at Crofton

As would be expected with such an old structure, there is always a long list of maintenance jobs needing to be done. Some of these jobs can be done whilst the general public have access to the building, others can only be safely carried out when the station is closed.  During each summer, a work programme for the coming winter closure is drawn up. The tasks usually cover every aspect of the facility. Examples are repair/refurbishment of the buildings and services, improvements to public facilities and examination and rectification work of major internal engine components.

Before any of this work can be carried out, a routine process of winterisation must be completed to examine the condition of the engines and plan for any deterioration that may have occurred during the summer season and to protect the plant from the harmful effects of winter frost and dampness. In addition, the boiler must be dismantled and cleaned out to enable it to be given its annual safety inspection.  Once the boiler has been inspected, it, too, is protected against frost and corrosion for the winter. The work described takes several weeks to complete and often results in further jobs being added to the maintenance programme. The following paragraphs describe this winterisation process in more detail.

1)  Start of Winter

Boiler

The fire doors and fire bars are removed, the water is drained and the mud hole and man hole doors are removed. The water spaces are then cleaned out by pressure washing and dried by the use of warm air. This work is done by Crofton volunteers. Next, external contractors are brought in to remove the soot from the boiler sides and flue spaces.  The boiler inspector then carries out a detailed visual inspection of its condition, both internally and externally. Once this has been done, and a clean bill of health given, trays of dehydrated lime are placed in the water spaces and the boiler is sealed so that it remains dry internally throughout the winter.

Engines and Ancillaries

The water is drained from the condenser tanks and they are washed out with a pressure washer to remove sludge. The circulating and air pump non-return valves are opened up and examined for condition and proper operation and the ducting and pipework are inspected for satisfactory condition. The non-return valves in the boiler feed pumps are dismantled and checked for satisfactory condition, and the seats ground-in if necessary. All operating linkages are examined for wear and proper function.  All bright metal surfaces of the main and auxiliary engines are treated with a corrosion inhibiting grease. Whilst this process is carried out, the components are examined for wear and/or damage.

2)  End of Winter

Boiler

The boiler fire bars and furnace fronts are replaced. The trays of lime are removed, and the man hole and mud hole doors are replaced using new gaskets. The blow-down valve is dismantled, cleaned, ground in, and reassembled with new joints.The boiler is then filled with water to its operating level and water conditioning treatments are added. This first fill takes over two days as there are some 1800 litres (4000 gallons/18 tons) of water involved.  A couple of weeks before the station reopens to the public, the boiler is steamed privately for the boiler inspector to observe satisfactory operation of the safety valve. This first raising of steam is done gradually over a period of 48 hours to minimise stress on the boiler shell.

Engines and Ancillaries

The valves in the condenser tanks are closed up with new gaskets if necessary, and the tanks are filled with water (this takes approximately 2 days for each tank because of the volume of water involved) and the  boiler feed pump valves are reassembled. The grease is removed from the bright metal surfaces and any corrosion removed.  Paint work is given a wipe down and repaired as necessary. All operating linkages are rechecked for proper function.

Once the boiler safety valve test has been completed, the engines are run up and any snags that have developed over the winter are dealt with.

3)  Additional Periodic Boiler Work

Every other year, in addition to the work described above, the little firewalls behind the fire bars inside the boiler furnaces are removed to enable this area to be inspected. At the end of winter, these have to be rebuilt before the fire bars are put back in.

Every 10 years, the insulating brickwork over the top of the boiler has to be removed to enable the boiler inspector to examine the exterior of the boiler. The amount of work involved in removal and replacement of the brick work for the boiler’s 10 year inspection usually precludes any other major work being done during that particular winter period.

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