Once again a complete year has past since the last Pearl update. But finally Pearl is finished. Not steamed yet, but ready to go as you can see from the heading picture. Some of the reasons for the delay are due to the modifications I made to the basic locomotive. I decided to change the crosshead pump boiler feed to a conventional bypass arrangement. I also wanted to make the cosmetic sanders supplied as an option by Maxitrak, to fully working sanders. And, of course, I had to install and make a linkage for the proper cylinder drain cocks that I had machined the cylinders to accept when I did stage 2. I also decided to put proper insulation and cleading on the boiler instead of just painting it as suggested in the instructions. But first I had to finish the cab installation.
The cab is very basic. Just a weather board in front and a roof. The bottom of the weatherboard is attached to the steel inner sides of the bunkers and spacers are used to center it correctly. The rusty condition of the sheet steel parts is the price I paid for taking so long on the project! Fortunately it was only a light surface film and cleaned off easily with a rust remover.
The front of the roof is supported on the framework of the weatherboard. The back of the roof is supported on on two steel frame pieces that bolt to the rear buffer beam. If left like this the assembly is not very strong, and so two braces are needed that go from the weatherboard to the top of the tank. These are prototypical and make the entire cab very firm and strong. The braces are supplied as two straight steel bars with eyes crimped on at one end. The instructions call for bending them to fit and hammering the bent section flat and drilling holes for the mounting screws into the tank. I decided to do this "properly" and resorted to a little blacksmithing.
The first step was to bend the braces at the right place. This was done cold. I then heated the ends with the propane torch and hammered them flat. Holes were then drilled in the flat section for the mounting screws and the ends filed to shape to neaten them up. They were then fitted between cab front and tank and produce an extremely rigid structure. The locomotive now looked complete.
The prototype Kerr Stuart locomotives have sanders comprising two small sandboxes mounted on the front of the saddle tank, with pipes leading down to the track just in front of the front driving wheels. A mechanical linkage back into the cab controlled the valves for the sand. When you buy the optional sander kit from Maxitrak you get two cast aluminium sandboxes with dummy fillers and sand pipes and the mechanical linkage. My challenge was to turn this into a working sander arrangement.
The first thing to do was to modify the sandboxes. The dummy sand pipes were just steel rods locktited into the bottoms of the castings. These were removed and the holes drilled out to take 1/4" copper tubes. I also removed the dummy filler caps and drilled 1/2" holes in the tops of the boxes and turned up two new filler caps. This is a picture of the modified sand boxes with the new pipes fitted. The original dummy pipes, which are much too short anyway, are seen behind the boxes along with the original control rod that goes between the two boxes. This rod only just entered each box when they were mounted, so I had to make up a longer one that went well inside each box. You can see the old rod resting on top of the boxes in this picture.
The last thing I had to do to the sand boxes should have been unnecessary, but Maxitrak had goofed again. The control rod for the sand valves goes between the two sand boxes between the stack and saddle tank. The holes drilled in the sand boxes were too far forward, so that there was no way the rod could fit, it fouled the stack. So I had to swap left for right and drill two new holes for the control rod. This is a picture showing the control rod in place and the incorrect holes. As you can see they are too far forward and any rod placed in them would have to go through the stack!
The next challenge was to make up the sanding valves. I used thin walled brass tubing that fit over the copper sand pipes. I filed apertures in the sides of the copper pipes that would be opened or closed by sliding the brass tube up and down over the aperture. To control the valves I soldered washers to the tops of the brass tubes and used a 6BA screw through the washer and into a lifting lever made from some scraps of brass hex and bar. The arrangement can be seen in this composite picture of the sand valves. The view on the left shows it open and the one on the right shows it closed. It was at this point that I decided to take the engine apart and remove the boiler to paint everything and then I could do a final fit of everything.
You will remember from stage two that I machined and tapped holes in the cylinders for proper cylinder drain cocks. The loco as supplied from Maxitrak uses a drain valve in the exhaust line from the cylinders to drain condensate, and I preferred to be able to drain directly from the cylinders. The drain cocks were fitted and I made up linkages to connect them to an 1/8" rod that went across the loco just behind the cylinders. This rod was connected via a lever to the control rod from the cab. This worked well and I used the original control rod supplied with the kit. As you can see from the first picture the cylinder cladding has been painted and installed.
The mechanical lubricator was fitted on a bracket on the right hand side frame and plumbed into the steam line via a spring loaded check valve. This was a simple installation. The mechanical drive is taken from the valve rod. I hadn't installed it when the picture was taken.
I did not take any photos while making the boiler cladding. But basically I used very thin brass sheet sold by Reeves as boiler cleading and cut it to size and cut out holes where the various boiler mounting bushes are. The cleading was then sprayed with an etch primer and then a heat resistant black automotive paint. The boiler was covered with a ceramic fiber insulating cloth and the cladding placed over it and secured with the brass bands supplied with the kit. The smoke box was not lagged. I just painted it and the stack with Reeves semi-gloss smokebox paint. The finished and re-mounted boiler is seen here. I also lagged the steam pipe by wrapping cotton string around it. I don't know how effective it is, but it certainly looks good and may save few burnt fingers! I had now painted the rest of the engine and so I could start the final assembly. Here is a view of it with the left bunker installed. You can also see the cylinder drain control lever on the left of the footplate.
As mentioned in the Stage 3 section, I purchased the optional injector kit. I needed to make a bracket to support the water shut-off valve that mounts under the right footplate. I showed a photo of this valve in the previous section and Tim Sanderson emailed me and pointed out that the inlet and outlet connections were reversed. He said:
I may be wrong, but I believe that you have the feed and delivery connections on your injector water valve reversed. The principle is not to have the water pressure against the valve gland when shut off. I agree that the valve needs to be supported; however, my injector has functioned OK supported on the pipes.
He is, of course, correct so I changed it and then made up a bracket. Here is a view of the valve firmly fixed to the footplate by a U bracket and with the pipe connections corrected.
The mechanical feed pump is located in the right-hand bunker. The plumbing is straight forward and takes water from the saddle tank and pumps it into the boiler via a clack valve on the right hand side. Here is a view of the piping. In this view you can also see the balance pipe that runs under the boiler to connect the two sides of the tank.
The third method of boiler feed is the crosshead pump, and this is where I had a lot of extra work. Part of it was my dislike of the Maxitrak method of controlling the feed with a valve on the intake side of the pump, instead of the more usual bypass arrangement. So I re-did the plumbing entirely on the left side of the engine to incorporate a T connection and an additional pipe from the tank to enable a proper bypass valve to be used. I was able to utilize the piping supplied by Maxitrak and cut, re-bend and re-solder them to fit. I used a threaded T connector casting I had from Stuarts, and made up the additional pipe. This is a test layout of the connections on the bench before fitting up.
However, before it could be fitted to the loco I had to solve a major problem with the mounting of the crosshead feed pump. The motion bracket on the left side of the engine has a large hole for the feed pump body to go through. I marked off the holes for the mounting screws and drilled them out and then assembled the whole lot back on the loco. But when I came to test the throw I found the coupling rod fouled the bottom of the pump body. I had to take it all down and file the large hole into an oval and drill four new mounting holes 1/4" above the originals. This shows the old holes with the pump re-installed. Even then you can see there is very little clearance between the rod and the pump. If you remember I had to file the motion brackets to clear the rods and wheel flanges in stage two. With hindsight I could have solved the problem by just filing the mounting holes on the brackets instead, and then I wouldn't have had all the problems with the clearances and the pump. This is a very good argument for purchasing stage 4 with stage 2 as there are a lot of parts in stage 4 that really should be fitted during stage 2. The bottom line, though, is that Maxitrak messed up on the motion brackets.
However, once I had fitted the pump the rest of the plumbing went on OK and this is what it looks like on the left side of the engine. The pipe at the extreme right of the tank goes straight down and into the inlet side of the pump, which is the bottom connection. The top connection on the pump is the outlet that goes to the T piece. The left of the T goes via the bypass valve back to the tank. The right goes to the clack valve on the boiler. You can see the rod that controls the valve running horizontally from the valve behind the bunker. The control wheel is in the cab. If the valve is opened the pump just recycles water back to the tank. When it's shut it forces water into the boiler. Cracking the valve slightly varies the feed to the boiler.
The rest of the boiler fittings were then installed and here you can see the regulator and controls on the top of the boiler in the cab.
This is a view of the installed sanding gear after painting and final fit-up. The picture below shows another view of the finished Pearl. The next step is to get steam up and run her. I promise it won't be a another year before that happens! Of course, I now have to build a couple of riding cars and think about a track. Will this saga ever end?
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