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| Repairing the damage to SOO 2719 | ||
| In the early morning hours of Sunday, 9 May 1999, ex-SOO 4-6-2 2719 was struck by a Wisconsin Central freight while being stored after a series of excursions. Damage to the locomotive included the air compressor, boiler, and running gear. One positive outcome of the unfortunate incident is the chance to photograph the sort of work that was once done daily in hundreds of railroad shops nationwide, but which is now rare. | ||
 On 8 May 1999, just hours before the accident, No. 2719 hauls her excursion train at Cadott, WI, on the Wisconsin Central. Photo by Alan Miller. | ||
| When 2719 was returned to service between 1996 and 1998, Scott Lindsay of Steam Operations Corporation and Gary Bensman of Diversified Rail Services were the prime contractors; both companies are performing the repair work as well. Scott is using the machine shop facilities of Lunar Tool & Machine in St. Louis, MO, and Tennessee Valley Railroad Museum in Chattanooga, TN. (For a detailed look at the shop, see Jeff Terry's "Lineside Legacy" column on page 16 of the March, 1999 "Railfan & Railroad.") And of course the volunteer members of the Locomotive and Tower Preservation Fund, 2719's owner, are doing a part of the work as well. | ||
| The following photos have been provided by Scott Lindsay, Mark Ray of TVRM, David Peterson and Mark Fay. Many can also be found on the L&TPF web site in the Gallery, maintained by Randy Lambertus. | ||
| Disassembly | ||
 | 2719 is hoisted by four interconnected hydraulic jacks at the ex-C&NW roundhouse in Altoona (Eau Claire), WI. If a working drop pit were available it would have been used. The drivers are being rolled out from under the locomotive. When they are clear, the locomotive will be lowered onto its lead and trailing truck and rolled back into the roundhouse. (For a complete look at the lifting process, check the 2719 photo gallery, pages 40-42. | |
 | The area where 2719 was struck is shown here. The impact sheared the four studs, drilled into the boiler shell, used to mount the air compressor. The jacket and lagging (insulation) has been removed, and the holes have been tapped and plugged to perform a hydrostatic test of the boiler. The entire area will also be given an "ND" (non-destructive test using ultrasound, magnetic testing, or xray) to determine if work on the boiler shell will be needed. | |
 | 2719's drivers have arrived at TVRM's shop in East Chattanooga, and two sets have been blasted to permit detailed inspection. From left to right we see the second (main), first (lead), and third (rear) driver sets. | |
 | David Pugh of TVRM, Bob Yuill, and Scott Lindsay remove a tire from 2719's left rear (L3) wheel center. It can be seen in the background that the other tire has already been removed. The axle and wheel centers are supported by the red cradle - the tire will be kept from falling over after it is removed by the clamp and chain seen at the top of the picture, which also holds the gas fired "ring of fire." | |
 | With the tire heated and expanded, sledge hammers are used to "ease" the tire off the center. Note the safety equipment worn by the workers. This process is commonly, but incorrectly, referred to as "sweating" tires. As Scott says, "The only thing that sweats during this process is the worker." (To explain, "sweating" is the process of soldering or brazing two parts which have a slip, or clearance, fit. Tires have an "interference" fit; before assembly the inside diameter is actually smaller than the outside diameter of the driver center, and the two are held together by the friction resulting from the force created (tension in the tires, compression in the cast centers). | |
| Running Gear Explained | |
 | This is a left side view of the rear axle area, looking toward the rear of the locomotive. Starting from the bottom: marked by "A" is the binder, which is a heavy, removable piece of the locomotive frame. It bolts under the driving axle box (missing in this picture) to secure the axle, the shoe, and the wedge (explained later). The cavity indicated by "B" is where the driving box and the axle fit through the frame. Between the box and the forward frame jaw (on the left in this view) you would find a brass "shoe;" to the rear you would find a brass "wedge." "C", "D", "E" and "F" illustrate the "spring rigging." The bottom of spring saddle "C" mates with the top of the driving box; "D" is of course the spring itself; and "E" are the spring hangers which connects the spring either to the frame (at the back) or to an equalizer (at the front). The equalizer "F" is connected at its midpoint to the locomotive frame (behind brake hanger "g", not a part of the spring rigging), and at each end to a driver spring. The result of all this metal is three driving axles which can move up and down within the frame, sprung by a spring rigging system adjusted to (a) distribute the locomotives weight as it was designed, and (b) keep the locomotive level. ("h" illustrates the frame itself.) |
 | (This photo has been rotated for illustrative purposes.) A driving axle box is shown here. Driving boxes are steel castings which have a central cavity into which brass can be poured to create a bearing surface. (The box comes in two pieces, and is assembled around the axle before the axle is placed in the frame.) The brass is bored to fit over the machined axle (see next photo), and the outside face is also prepared with either brass or "babbitt" (a soft alloy) to meet with the hub liner (see the photos above and below) and control lateral motion of the drivers. The front and rear faces of the box fit over the shoe and wedge, respectively, which in turn fit over the frame jaws; the round cavities in the faces trap lubricant. (Remember the drivers move up and down in the frame as the locomotive encounters dips and rises in the track below.) There is no bearing face below the driver; the "grease cellar" can be seen below the axle space. (Drivers are lubricated by a "cake" of hard grease mixed with soap, held against the bottom of the axle by a spring, all housed in the grease cellar. The grease can be changed by opening the cellar while lying between the rails or standing in an inspection pit between the rails.) The top of the box mates with the spring rigging; a pin on the spring saddle fits into a hole in the top of the driving box. The result: an assembly in which the brass wears and can be replaced as necessary, and the steel will not wear significantly during the life of the bearings. (Axles and frame jaws do wear, and axles occasionally need to "turned" (machined) or replaced; frame jaws can be built up with weld, or shims welded to the face and machined to return the locomotive to its original specs.) |
 | (This photo has been flipped for illustrative purposes.) Drivers consist of two cast centers (one is shown here, the other is mounted at the other end of the axle) pressed with great force onto a forged axle. The pins which connect to the drive rods (the back of one if visible in the upper quadrant) are pressed into the centers with an interference fit. In this way the parts that eventually require replacement (axles, pins, tires) can be renewed without recasting the center. Note the difference in the axle surface - the portion closest to the wheel center, where the axle bearing box fits into the locomotive frame, is polished, while the remainder is left unmachined. The hub liner, which would encircle the axle and face inward to meet the driving box, has been removed in this photo. The holes visible in the wheel center casting are filled with lead in varying amounts to balance the entire assembly - this allows imperfections in the casting, slight differences in rod weights, etc. to be counteracted. |
| Casting a new Driver Center | |
  | 2719 will receive a new left rear driver center. The two halves of the center pattern are shown here. Casting patterns are made of wood slightly LARGER than the finished casting to allow for the effects of cooling on the steel. (A "pattern ruler" has length marks that won't match a normal ruler.) "Foundry sand" is packed tightly around each pattern to create a mold, the two molds mated, and . . . |
 | . . . molten steel is poured through the "slugs" shown attached to the mold. The finished casting is then machined to accept the axle, pin, and tire. |
| Repairing the Driver Damage | |
 | The tire has been removed, and the damaged caused by the collision can be seen. A small piece of the counterweight has been shorn off, and a large crack is forming in the wheel center. This crack will have to be ground out and built up with weld. Depending on the type of iron or steel used to cast the center, the entire center may need to be heated during or after welding. (Those performing the work believe that this wheel center is an inferior replacement casting. It is possible that this wheel center was replaced when 2719 received her new main driver centers in the 1940s.) |
 | Another large crack has been found where the spokes meet the center of the casting, and has been ground out in preparation for welding. The "hub liner" (a two-piece thrust bearing which faces the axle bearing and box that fits around the machined portion of the axle) can be seen attached to the inside face of the wheel center (the sunken circular areas). |
 | Yet another crack, this time at the tire end of a spoke. More grinding and welding will be needed. |
 | Bart Higgins welds the cracks in one of the lead driver centers. |
 | More crack repair, this time on the R3 center (attached to the axle). |
 | The main axle has had thin steel "liners" welded to the outside of the center. These liners are being turned on a lathe to return the center to its correct diameter. The result is centers exactly the same size as they were when the were originally cast. |
 | Another view of a driving box, this time with the grease cellar removed. |
 | Terry Dawson is making a new axle out of a steel blank. He's reducing the diameter of the ends to fit in the driver centers; the purple machinists "bluing" marks the approximate locations of the two journal surfaces. |
 | After the axle ends are the correct diameter, Chris Storm mills a keyway into each end. The keyway will be fitted with a temporary key (a piece of steel sized to fit) as it is pressed into the center. A permanent key is fitted afterward. The result: Driver centers mounted almost precisely 90 degrees apart in radial alignment, and kept from rotating on the axle while in use. |
 | Back in Chattanooga, these well-travelled drivers have been fitted with tires, which are being turned to the proper diameter and profile in TVRM's ex-B&O wheel lathe. The pins that hold the side rods will also be machined until they are EXACTLY 90 degrees apart in radial alignment. |
 | TVRM's George Walker (l) and David Pugh (r) turn the journal surfaces on the axle. |
 | 2719's main driver is ready for work in the quartering lathe (foreground), while driver no. 3 is mounted in the journal lathe (background). |
 | George Walker of TVRM turns a journal (bearing surface) on the no. 3 axle. |
| Tramming the Running Gear | |
 | Once all the steel parts have been machined, the locomotive must be "trammed." Tramming involves determining the precise distances to which the drivers and rods must be aligned for everything to fit together and work as intended. Once these measurements are taken the brass shoes, wedges, pin bushings, and the steel spring rigging shims can be fabricated. The first step is to jack the locomotive up and get it precisely level. |
 | Step Two is to strike a line through the EXACT center of the cylinder from which all measurements will be taken. If the cylinder is bored true, the line will be exactly parallel to the frame; if not, stop and rebore the cylinders. The head end of the line is shown here; the four screws allow you to locate the line precisely. |
 | The line is shown here passing through the crosshead hanger. The rear of the two guides (one above, one below) that hold the crosshead (which connects the piston to the main rod) will be mounted to this casting; the front of the guides mount to the rear of the cylinder. |
 | The line can be seen passing alonside the frame. The front and rear face for the "pedestal jaws" (the opening that contains the driving box) is being located with the tool that looks like a "Z" on its side. This process is repeated for each pedestal; the result is a series of measurements used to calculate the thickess of the shoes, whether any rod bushings must be bored off-center to compensate for rod length variation, and the dimensions of the crosshead bearings. |
| The Finished Product | |
 | Back together, there's no clue that anything ever happened - a tribute to the hardworking L&TPF volunteers and their consultants. |
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