Sunday, 12 February 2017

Maintenance Update (cylinder, chain, shaft, pin)

Wednesday 8th
Having been put on a new type of pill, Gilbert was back to his normal self, and was joining in everything again. However, he couldn’t get inside the cylinder to measure the internal bore, so John T did that. It appears that the cylinders have worn differently on each side - something that is not easily explained immediately.

Brian (with assistance from Gil) worked on the cylinder covers, starting with taking the RHS cover off (otherwise how could John climb inside?). All of the studs were cleaned and dies run down them; all of the nuts had a tap run through them. John T worked on the RHS, while Brian fitted PTFE seals to the two covers. At the very end of play, Gil, Brian, John and I fitted the cylinder covers back on. Gil manned the pulley; Brian applied the brawn. Alex gave encouragement.

John G was wielding his paintbrush once more. Beginning with the proverbial black bottoms (of the rail chairs that were cleaned last time) he moved on to applying a coat to the inside of the cylinder cladding.

The outside will get a coat later, as it is planned to repaint the black running boards and anything nearby. Hence the step that also holds the vacuum pump got a coating from John, too. Apparently it had been noticed (during the mechanical inspection by GWSR) that a rivet was loose. David fixed that so John painted it!

John T had completed the components of the gadget that he designed for guiding the loco/tender links into their correct holes. David welded it all together, even manufacturing a handle from a length of fencing that he found in the skip. Needless to say, John G painted it. Here it is standing upright inside our container.

Bruce had brought some chain from home. Two lengths of chain had suffered at the hands of footplate crews: there is a chain retaining a pin inside the smokebox which is used to secure the bar that is behind the smokebox door and into which the dart slots when closing the door; there are chains on the lids of the sandboxes, too, one of which had given up the ghost. So, David cut, fitted and welded new chain into place.

Bruce lapped the clack valves internal to the two injectors, so these are all ready to be reassembled and fitted.

John P [Loco Dept - performing mechanical checks] spotted that the brake column on the tender is not as secure as it might be. Bruce removed the cover plate and peering down, it became obvious that there are only two bolts holding the flange at the bottom of the column. There is no room for any more bolts down there! However, other tenders have got a bracket towards the top of the column, which holds it steady. John P said that the column could fracture and hence we should manufacture a retaining bracket.

Bruce’s homework this week is to ream the taper in the rocking shaft such that the new pin is a perfect fit.

Brian helped Bruce lift it into his car; I followed Bruce home and gave a hand lifting it out again.

Friday 10th
Bruce reported: “I have finished fitting the offset pin into the rock shaft. It was quite a long winded job as the removal of small amounts of metal from the diameter has a much greater effect on the amount the pin goes into the taper.”

Saturday 11th
Loco Dept wanted to fit new brake blocks to the loco, which meant being over a pit to undo the mechanism that connects all brakes together (so that individual ones can be removed and replaced). This meant coupling loco and tender … which meant an opportunity to test the connection jig that John T (in particular) designed. It did work, but some instructions will be necessary for those who are not familiar with it.

When the team from Loco Dept got to work and removed the old brake blocks, they discovered that the new ones wouldn’t fit! They are too wide at the pivot point, so a small amount needs to be machined off each one. So, the loco was pushed back into the shed.

A few minor tasks were carried out, such as: painting rail chairs, cleaning up the outside of the cylinder block, locating and acquiring some insulation to replace that between blocks and cladding.

However, the Big Task of the day took the whole team plus helpers from Loco Dept: this was replacing the LHS rocking shaft and connecting up the valve.

For a start, the rocking shaft is a two-man lift. Getting it up onto the running board was no mean feat. Bruce cleaned up and smeared oil on the brass shells. These two shells do not sit horizontally; they incline at perhaps 60°. The outer arm of the rocking shaft (black) has to pass down through a slot in the running board. Then the shells had to be clasped around the shaft (using Bruce’s fingers) while two chaps used a bar through the centre to manoeuvre the whole thing down into its saddle.

The top cover went on and was bolted down. At this point, Bruce rocked the whole thing to-and-fro to make certain that it was not too tight! With the oil pot fitted back on the top, this stage was complete.

The next step was to fit the valve link between the rocking shaft (outer black arm) and the valve spindle crosshead. That’s not too difficult apart from the fact that the taper pin is in the rocking shaft end, meaning that the link has to be rotated sufficient to get the pin into its hole.

Meanwhile, at the other end, the valve spindle crosshead was refitted and connected up to the valve spindle. Needless to say, the valve (and hence the crosshead) had to be pushed forwards before the link would engage with the crosshead. That done, the outside motion was complete.

Back inside the frames, the rocking shaft arm (red) needed to be connected to the intermediate valve rod that joins the rocking shaft to the die block in the expansion link. So, I volunteered to go in the frames this time; John T manned the reverser in the cab, and someone on the outside pushed the valve further forwards, sufficient for the rod and the arm to mate. Phew!

If you look it up in The Engine Driver’s Manual or the BR “Black Book” you find this diagram:


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