February 2022 saw a significant milestone when No. 2007 Prince of Wales
had both sets of coupling rods fitted for the first time.
The left-hand set had been mounted on their crank pins for the 2021 Convention, however a fair amount of machining work has been required to complete the bearing bushes and gradient pins for the second set of coupling rods. The process of fitting the rods to the crank pins is achieved using four small chain hoists suspended from specially designed "sky hooks" under the footplate on each side of the engine. The chain hoists can be seen in the photo below. The chain hoists avoid manual handling of the rods, which particularly with an eight coupled engine is a hazardous practice.
David Elliott and Ed Laxton prepare to lift the first coupling rod to be fitted - A1SLT
The process was repeated until all the rods were in place - A1SLT
Job done! Now for the other side! - A1SLT
For the first set of rods to be fitted, the crank pins are set by eye to all be at the same angle. The rod assembly (three rods and two gradient pins) is lifted and swung into place over the longest crank pins first. Small angular corrections of the positions of the other crank pins are made by oiling the contact point between each wheel and the rail and using a crow bar through the spokes to slightly rotate the wheelset. Once all the rod bushes are fully home on their crank pins, the other set of rods can be fitted with the reasonable expectation that the crank pins are already in line, aided by moving the engine a few feet with a pinch bar.
The first set of rods in place - David Elliott
P2 Director of Engineering, David Elliott remarked, "It was with satisfaction (and relief) that the second set of rods slid onto their crank pins with distinct "thunk" noise."
The engine was subsequently moved about 10 feet (half a turn of the wheels) to check that nothing was binding anywhere - and it wasn't! It indicates that all the measurements of distances between hornblocks, thickness of hornblock liners, sizes of crank pins and bushes and the relationship between crank pins on each wheelset and to one another had worked out correctly.
The second set of rods (left-hand side) fitted - David Elliott
We look forward to the next part of this process whereby the locomotive is lifted onto the rotator for the wheels to turn for longer periods at higher rpm. Watch this space!
Here's one we built earlier! Tornado's wheels are rotated - A1SLT
None of this would have been possible without the generous donations made by members of The Motion Club
. You can help us replicate this success by supporting one of our other Clubs, or by signing up as a Covenantor