August 2026

The weather had cooled significantly by the time of the August working party, much to our relief!

Jack again offered his excellent turning skills, and was set to making up the valve glands and dummy glands (the part which the gland presses against). These need to be a press fit in the gland housings. They also need to be a precise fit over the valve spindle sleeves, with only the minimum of clearance. We have now had the valve spindle sleeves ground, so we know the exact inside diameter of the valve glands. The precision is required because the C2 does not have a valve crosshead; the gland alone aligns the valve spindle.

Since the valve gland and dummy gland are in two separate housings which bolt together, Dave suggested fitting the glands into the housings before boring the insides. The insides can be bored when the two parts are bolted together, to ensure that the inside diameters are on a common axis. Jack therefore turned the outsides of the glands until they were a perfect push fit into the housings. Next time he is able to help us, we will ask him to repeat the exercise for the dummy glands (which are rather longer).

Before the working party, Andrew had expressed a wish to be able to finalise the little end bearing dimensions. While most of the little end bearing dimensions are already known, the exact lateral position of the connecting rod relative to the crosshead was not. While it should be perfectly on the crosshead centreline, we knew that there was an existing misalignment on both sides of the locomotive. We felt that this misalignment could be minimised by putting a very slight bend in each connecting rod. Given that the connecting rods are approximately 5 feet long, a few millimetres offset between the two ends will be imperceptible, but will centre the rod relative to the crosshead.

Of course, how much of a bend was required in each connecting rod depends on the lateral positions of the big end bearings. This was yet to be decided, so Dave and Erle took a look at the 'as measured' motion assembly drawing which Erle had prepared. We don't want the big end bearing to be too far out, as that means the return crank has little to be fitted onto. But we don't want the big end bearings too far in either, as there is very little clearance between the connecting rod and the driving crank pin cover bolt heads. Andrew and Dave agreed that on the driver's side we should leave the big end where it was drawn, since the clearances were adequate, but the Fireman's side needed to be moved outwards a few millimetres.

Using these agreed dimensions, Andrew could then start machining the big end bearing inside cover plates. These fit up against the crank pin bearing outside cover plates and thus determine the lateral position of the big end bearings. The cover plates didn't need to be finished; just machined enough so that were the correct thickness and could be fitted over the roller bearings which form the big end bearings. Andrew worked his socks off to get these plates to a usable state as quickly as possible!

With all the components ready, the crossheads and connecting rods were loaded into the cab of the C2 for a shunt around to 4-Road, since that siding is the closest we could get to the press we wanted to use. Needless to say, first we had to shunt various wagons off the C2 Shed road before we could move the locomotive. We also shunted the tender onto an adjacent siding, as we didn't need that. It's always nice to see the C2 out in Boston Lodge yard, and Dave was happy to have a drive of the Castle Aarrrggg diesel shunter. As the C2 stood near the yard exit a passenger train passed by, giving those on board a rare glimpse of the C2 out in the sunshine.

We started with the fireman's side. The crosshead was assembled onto the slidebar, using specially made dowels to fit the two parts together. Then the big end bearing inside cover plate was placed over the driving crank pin. Next it was time to lift the connecting rod and slide it on to the driving crank pin. Due to the very fine tolerances within roller bearings, a bit of wiggling of the rod was required to get it onto the crank pin; not so easy when you're trying to support the weight of the rod while hunched over the crosshead assembly. With measurements taken, we knew how much we needed to bend the connecting rod by.

We had intended to use the screw press to bend the connecting rods, but after clearing the bench on which it was sitting, devising a means of supporting the rod, and lifting the rod into position, we found that we could not exert enough torque on the press to bend the rod. Time to fall back to option 2; the hydraulic press. Since we know that the hydraulic press is not so controllable as the screw press we devised a supporting arrangement which we hoped would give us an indication of how much we were bending the rod. The bend needed to be near the big end bearing, so a pair of supports was arranged at that end of the rod. The other end was supported by a trestle with an adjustable clamping block on it, so that the rod was supported at three positions. By applying force between the two supports at the big end, the little end would lift off the clamping block. Since the little end is a long way away from the bending point the movement is amplified by the geometry, so the tiniest bend would result in a movement of several millimetres at the little end; quite easily seen.

The problem is that steel is quite flexible, so what looks like an enormous bend is within the elastic limits of the material, and the rod returned to its original position when the force was removed. A bit more force was applied with the same results. And a bit more force, held for slightly longer. This time, a permanent offset could be detected. So it was time to carry the rod back to the locomotive, refit it and re-measure. Bother! The rod had bent too much. So, off it came again, and back to the press for some remedial bending. With some practice we started to get a feel for how much visible deflection at the little end would result in a permanent bend in the rod. Each time we detected a permanent deflection, the rod had to be carried back to the locomotive and refitted. Given that each connecting rod is a two man lift, you can appreciate why we wanted the locomotive as close to the press as we could get it!

It took several hours of trial and error (and carrying the rod back and forth), but eventually, when the rod was fitted to the crank pin, the little end lifted up almost exactly under the centre of the crosshead. A final set of measurements of clearances between the little end of the rod and the inside faces of the crosshead were taken, and the job was declared complete. Then it was on to the driver's side the following day.

Without going into boring repetition, the same process was carried out on the driver's side connecting rod. We were becoming better at judging the forces required to bend the rods, which resulted in more trial and less error. But the driver's side also took several hours to arrive at the ideal alignment. Andrew, Ed, Chris and Dave did most of the lifting, fitting and measuring work, although, after Chris and Ed had left us on Monday and Dave's back was beginning to object, George offered to assist and so got roped into helping carry the rod we were working on. Thanks to this concerted effort we are now ready to start drawing up the little end bearings.

Erle was continuing his excellent work on the screw reverser. As part of this, he was repairing the old the latch handle (which holds the notched wheel) and is mounted to the rear bearing housing for the reverser screw shaft. The bearing housing holds a pivot shaft for the latch handle to rotate on and a stop for the handle to come up against when the handle is in its raised position. Both are riveted in place. The pivot shaft was badly worn and a very loose fit in the handle and its thread for the retaining nut was also badly damaged. The stop was also bent and short in length.

First job was to remove the riveting holding the stop using a Dremel with a small Burr allowing it to released. The pivot shaft had previously been removed this way.

The handle also needed extra material adding to it due to excessive damage/ wear in two area's. 1) contact surface with the spring steel leaf spring. 2) Contact face with the stop. Andrew added weld in these areas to increase material thickness. It was then off to the Chinese miller to set up the handle in the vice to trim the surfaces back square to drawing. Once this was done a bit of work with needle files to smooth in a small radius for the handle to rub against the existing leaf spring was carried out.

The pivot hole in the handle was next to be tackled. As it was well oversize and elliptical, a small bronze bush had been acquired to allow the hole to be bored out. As the bush was metric to match the pivot shaft, a search of the workshop was carried out for a suitable meteric reamer. Unfortunately one could not be located. It was then decided the hole would need to be bored out using a boring head. Work was then transfered to the Bridge Port miller which could mount the boring head. After some careful setting up with a DTI the miller was positioned over the center of the oval pivot hole as best as possible. The boring head was then used to bore the hole out to give the required interference fit for the bush The handle was removed from the miller and the bush press fitted into place.

The next task was to produce a replacement pivot shaft and stop. A suitable length of EN16 steel was found. Using one of the DSG lathes a new pin was turned to drawing with care taken to make the bearing surface for the bronze bush a close fit. The end the shaft was reduced and an M12 thread formed of a suitable length for a nyloc nut and new thrust Washer to fit. Once completed the thrust washer was next made. The final task on the lathe was to turn the new stop.

A quick assemble of the parts to the bearing housings proved every thing work correctly and Andrews welding services were again employed to secure the pivot pin and stop to the rear of the bearing housing.

The refurbished handle was then assembled onto the bearing housing assembly, and the old reverser screw fitted along with the new notched wheel.

A test of the latch handle gave a very positive clunk holding the latch plate firmly. After 3 days of work a very satisfying sound.

Andy used a wire wheel to clean any corrosion from the return rods, and as usual, did a very thorough job of it. A wipe over with a white spirit soaked rag removed any dust and grease, and then the rods could have primer applied. The following day, Andy painted the return rods in undercoat and then a coat of white paint. Ultimately the return rods, like the coupling and connecting rods will be natural steel finish, but as a temporary measure to prevent corrosion, white paint will suffice.

Since we are proposing to replace the plain metal bearings in the radius rod to combination lever joint with stainless steel and plastic, we need a blanking plug to fill the (hopefully) unused oiling point on the radius rods. Andy used a thread gauge to try and identify what thread form is in the holes. We suspected it was a metric thread, but it is definitely not a standard one. From Andy's measurements we believe it may be M22x1.25, so we'll try to buy (or make) a suitable blanking plug with this thread.

The lower end of each combination lever has a joint with the union link. This is in the form of a ball bearing mounted on a pin. Dave had previously designed and made the pins. The section of each pin which interfaces with the combination lever is slightly over-size compared to the original design, to compensate for wear in the holes. Dave had chosen diameters which correspond to reamers which he'd found in the racks at Boston Lodge, so we knew we had access to the necessary tools. Chris used these reamers in the Asquith radial arm drill to ream out the holes in the combination levers such that the pins are now a precise fit.

While looking at the combination levers, Chris questioned the fitting of the cover plates over the trunnion bearings on the valve spindle joint. Instead of a clearance hole, the cover plates seem to have been tapped along with the holes in the combination levers. This makes it very difficult to clamp the plates onto the combination levers satisfactorily. The fixing holes in the cover plates are very close to the edge, so we were wary of drilling them out to an M6 clearance size, but drilling them out to 6mm diameter was possible. After carrying this out Chris discovered that the corresponding holes in the combination lever were not tapped very deeply, which again may prevent the cover plates being properly fitted. Some careful use of an M6 plug tap deepened the threaded section of the holes to overcome this problem.

The round combination lever cover plates are a larger diameter than the depth of the combination lever. One of the four plates had been trimmed to remove the overhang, but the other three had not. Chris therefore trimmed the three offending cover plates so that all four are now a neat fit on the combination levers. Attention with a wire wheel removed any corrosion, and was followed by primer, undercoat and top coats of paint.

The August working party extended over a total of four days, and was very productive. With five people working together for much of the working party, we felt that we had regained the momentum that is sometimes lacking post COVID. We consider the working party to have been a great success thanks to all those who helped us. And with little end bearings, piston and valve rings being ready for design, it can't be too long before more of the motion is ready to be assembled.