South Devon Railway Engineering has just completed an extensive overhaul of the driving wheels from Standard 5 No.73082 “Camelot” which is based on the Bluebell Railway where it is currently undergoing a 10 year heavy general overhaul.

The driving wheels required retyring and also work on the roller bearings. The bearings were first examined to decide the way forward. The roller bearings on the engine are housed at each end of what is called a ‘cannon tube’ which completely encases the axle and is filled with grease. The axleboxes are an integral part of the cannon tube assembly and house the roller bearings. Shortly after 73082 was built the design was changed to a two part cannon tube — removeable without taking the wheel off the end of the axle. So, having established that two of the roller bearings were likely to need replacement, and in the absence of this sensible modification, the first process was to remove the wheels off the affected axles using the recently installed wheel press. This done, the bearings were dismantled for inspection and the cannon tubes overhauled. The next challenge was to source replacement roller bearings for the two axleboxes that needed replacement. Surprisingly, the exact design is still available “off the shelf” and two sets were obtained. One hates to think what the cost would be of making two such sets from scratch, so that was good! Next, the right grade of grease was obtained to pump into the cannon tubes.

That done, the wheel pans were refitted to the axles. Temporary keys are used to ensure the correct quartering is achieved and then the proper keys are fitted. If needed, quartering would be carried out on the SDRE’s quartering machine, but this was not needed as any variations were within tolerance. With all the wheels now back on their axles the final process was to machine the correct profiles onto the newly fitted tyres

Rob Le Chevalier, SDRE Works Manager, said, “We have really enjoyed this particular challenge, which represents the most comprehensive overhaul of a set of driving wheels that we have carried out. Having to resolve the engineering issues associated with the roller bearings was interesting to say the least and also enabled us to perfect the wheel press processes. The wheel press dates from the late 19th/early 20th century and was originally designed to use water as the hydraulic fluid. We have modified it to use oil and the experience gained doing the ‘Camelot’ project has been invaluable.”

The wheels will be going back to the Bluebell shortly, accompanied by a new front tubeplate for the engine that has also been pressed in the boiler shop at Buckfastleigh works.

Earlier news story on wheelpan removal.