Skip to content

By Darrin Crone on

Sir Nigel Gresley overhaul – Update 36

The restoration team gets the new year started with reassembly, machining and more.

Week commencing 31 December 2018

The tender water valves have now been temporarily put in the tender frames to provide a better idea of where pipework at the front of the tender can be routed. Meanwhile, the installation of the steam supply pipework to the governor progresses.

The governor that controls the air pump in its new location
The governor that controls the air pump in its new location with new pipe flanges and pipework being installed

The loco sidebearer faces were skimmed over the Christmas break, to make them true to the bogie-mounted sidebearer plates. The sidebearers limit the roll at the front of the loco. The dimensions taken before Christmas were used to calculate the necessary material to be removed.

The sidebearer on the left
The sidebearer on the left. The loco frames are resting on the top of the bogie when moved off the wheeldrop. When levelled the gap appeared and was measured

The sidebearers were refitted to the loco this week by lowering the bogie on the wheeldrop sufficiently to gain access to the lower edge of the loco frames where the sidebearers are fitted. The bogie was then re-raised and the gaps measured again. The left side measured to spec but the gap on the right was excessive. This was expected as the gap here was going to exceed spec as the bearer had curved during welding and more material had to be removed to get it flat. The loco frames were then moved off the wheeldrop back on to plain track near the buffer stop and it was noticed immediately that the loco was “sitting” differently and the sidebearer gaps had changed. We expected that movement of the engine would lead to settling on the new bearing discs between the bogie and loco frames and standing on different rail would affect the gaps.

To try and get a true measurement of the sidebearer gaps, the level of the frames and the bogie were carefully measured and found that the mainframes were leaning and loading one side of the bogie. So, the loco frames were jacked while the spring load on the bogie wheels was adjusted until both bogie and loco frames were level. In this state the sidebearer gaps were measured again. As expected after first fitting, the sidebearers require another finishing skim and this time we have some good measurement to work from.

With the bogie now in place the outside drain cock operating shaft has been installed and connected to the rest of the drain cock operating mechanism.

The outside draincock cross shaft
The outside draincock cross shaft has been fitted

Further machining has been done to the side rod bush castings with both leading and trailing pairs machined over all cast surfaces. The trailing crankpin end fittings have been trail fitted before measurements being taken which will fix the overall length of the bushes on these crankpins.

The trailing left crank pin end is fitted with the crank for the speedo drive
The trailing left crank pin end is fitted with the crank for the speedo drive. The gap between the crank and the face of the wheel will fix the length of the bearing bush fitted to this crankpin
The leading and trailing connecting rod bushes
The leading and trailing connecting rod bushes are now machined all over. The larger bushes yet to do

Work continues on pressure-testing the drain cocks. Two of the castings show porosity and were sealed by soldering before Christmas, however this has not totally stopped the leaks, so they have been re-soldered and await further testing.

The long conduit that runs along the left footplate angle has been paint-stripped. It’s always looked a bit tatty as the paint doesn’t adhere well to the galvanised surface. Some special primer designed for coating galvanised surfaces has now been tried and this should improve paint adherence.

The horizontal hornstay bolts sponsored through the pages of Chime are now all machined to their fitted diameters. They require drilling through for split-pinping.

The sponsored horizontal hornstay bolts
The sponsored horizontal hornstay bolts machined to dimensions ready to fit

The right driving axlebox returned from contractors after repair to the hornface was put up on the surface table and measured. The measurements will be used to set the horn gap on the loco.

The tender brake cylinders have been reassembled. Some further work is required to enable smooth operation as the fit of the piston rods in the new neck bushes seems tight. These cylinders are different from the cylinders on the loco in that the neck bushes are located in the covers not in the cylinder casting, so a little more clearance is required.

Examining a tender brake hanger
One of the tender brake hangers with the bushes and pins being examined

The tubing of the boiler at Llangollen progresses with the tubes being trimmed to length before expanding and finishing. The installation of the crown stays is well past half way.

The flue tubes are trimmed to length
The flue tubes in the boiler at Llangollen are trimmed to length

This is the 36th update—you can read all the previous instalments here.

Leave a comment

Your email address will not be published. Required fields are marked *