One of the original boiler tubes - complete with a hole!
The driving (or crank) axle
Rear view of the cylinder block
Slide Bars and Motion Bracket
Left-hand driving axlebox
Right-hand leading axlebox and both of the leading axle springs
Wakefield displacement lubricator
In this picture you can see what one of the old boiler tubes looked like when we removed it from the boiler. The finger is pointing to one of the holes that caused trouble from time to time during 828's latter years on the Strathspey Railway. When a tube fails like this it is accompanied by a loss of water, usually into the firebox, and results in the loco being taken out of use. Normal practice with 828 was to 'blank-off' such tubes by fitting plugs at each end and pulling them tight using a threaded bar which ran the nength of the tube. This was a hot and uncomfortable job if the loco was needed back in service quickly!
In this picture we see the driving axle after it has been removed from the loco. The loco is arranged with the right-hand crank leading the left-hand by 90 degrees. This is a very typical arrangement on a two-cylinder British steam locomotive.The throw (or radius) of the cranks is 13 inches (330.2mm). This gives the two pistons a stroke length of 26 inches (660.4mm).
Between the two cranks can be seen the eccentrics which operate the Stephenson's Link valve gear.
At the rear of the picture you can see the back of 828's tender.
This picture shows the back of the cylinder block and the slide bars which guide the piston rod slippers and crossheads. (The power from each piston is transmitted to the connecting rod through the crosshead. The crosshead slippers transfer the vertical thrust from the crosshead into the slide bars and protect the piston rod from bending forces.)
In the centre of the cylinder block (with a wooden cover on it) is the exhaust steam connection. When the loco is in working order the blastpipe bolts onto the top of the connection. Note how the years of service have caused the cylinder block to corrode. Fortunately there is still enough metal for it to work satisfactorily.
This picture shows the rear section of the slide bars and gives a good idea of the size of the motion bracket. The motion bracket is a girder construction which absorbs the vertical thrust from the slidebars, stiffens the frames and provides the bearing support for the valve spindle extension rods which drive the slide valves.
This picture shows the left-hand cylinder. In British Railway's days this cylinder was bored out and a cylinder liner fitted. The joint surface between the liner and the cylinder casting can be seen quite clearly. As part of the overhaul this liner will be removed and the cyclinder bored out a little further and a new liner fitted. The same task will be carried out on the right-hand cylinder. It has not previously had a liner fitted to it.
This is the left-hand driving axlebox bearing. The bearing itself is a very heavy bronze casting. The bearing surface which carries the weight of the loco is overlaid with lead / tin white metal. This material has very good bearing properties and is widely used on British steam locomotives. As the picture shows, the years of operation on the Strathspey Railway have resulted in the white metal becoming quite worn. Also shown is the cast-iron underkeep which is held onto the bearing by a large horzontal steel pin. It is via the underkeep and the axle spring that the weight of the locomotive is transmitted to the axlebox bearing. The bearing is lubricated by drip feed of mineral oil from an overhead oil reservoir. As part of the present overhaul, the drip feed oil supply is to be supplemented by a feed from a mechanically driven lubrication pump. This will help to improve the longevity of the bearing.
This shows the right-hand leading axlebox just after removal from the loco. The two leaf springs which transfer the weight of the loco onto the leading axle are lying beside the bearing.
The coil springs in the background belong to the driving axle. Claedonian Railway practice in JF McIntosh's day was to use a pair of coil springs to support each driving axlebox bearing.
This picture shows one of our Volunteers, Mr Graham Elkin of Inverness, working on the Wakefield displacement lubricator which feeds cylinder lubricating oil into the steam chest while the loco is in operation. The lubricator consists of a pressure vessel located in the drivers cab. It is partially filled with oil and then a small supply of steam is fed into it. The steam condenses into water and the vessel fills with a mixture of steam and water. Because of the different density of oil relative to water, the oil is slowly displaced by the continuous condensation of steam. From the lubricator vessel, the displaced oil is fed into the steam chest and povides lubrication to the slide valves and pistons.
