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 Vail, Pennsylvania. Photo by John Craft. | ||
| Few locomotives can stir up the excitement generated by the 1987 return to service of "the K4." Displayed from 1958 to 1985 at Horseshoe Curve near Altoona, it was overhauled in the same shop complex where it was built, and for a period of about 18 months it operated on Conrail and short line trackage in Pennsylvania. Since late 1988 this popular Pacific has been either a static exhibit in Altoona, or undergoing overhaul at Steamtown in Scranton, PA. | ||
| The following photos have been provided by Wayne Laepple, a volunteer on the restoration effort. As work progresses he will be updating this page with new photos. Wayne tells the story: | ||
| "This is one of the most thorough rebuildings of a locomotive to occur in recent years. It is literally a "jack up the whistle and rebuild the engine under it" approach. A great deal of the work being done was not originally anticipated, but as work in other areas progressed, it became apparent that this engine was one tired puppy when she was retired in 1956. (The PRR's philosophy by that time was obviously "patch up whatever is needed to get through the next boiler wash since those Geeps will be arriving any day now.) "The project is spearheaded by Jeff Miller, who has been involved in locomotive work for many years. Unfortunately his full-time helper has taken another position, so Jeff is once again working alone most of the time. Two or three faithful and hearty volunteers show up most Saturdays, and once in a while someone will take a day or two of vacation to work on a weekday. More volunteers are always welcome. "While the work is accomplished in Steamtown's shop, the work is funded from outside sources. Steamtown personnel do assist from time to time, however, and shop manager Chris Ahrens is Jeff's technical advisor." | ||
 Looking like a real steam shop from the old days, the Steamtown shop houses (L-R) Boston & Maine 4-6-2 3713, no. 1361, Baldwin Loco Works 0-6-0 26, and Canadian Pacific 4-6-2 2317. | ||
| The Backhead | ||
 | The boiler is the big-ticket item in this overhaul. Significant damage to the outer shell was done by a previous contractor, and the entire backhead area (known as the "wrapper sheet") is being replaced. The protruding rods are "boiler braces" to provide additional support for the wrapper sheet. As can be seen, the rear of the firebox (the "door sheet") is being replaced as well. | |
 | Another view of the rear of the boiler. Note the polishing where the brick arch meets the side sheets; some patching, staybolt replacement, and new studs to receive the arch will be needed. | |
 | The new wrapper sheet is shown here, held upside-down by chains. The boiler brace gussets are held in place by bolts, which are being replaced by rivets. | |
 | Backhead braces attached to interior brackets will be attached to the backhead (the braces are at the "bottom" of the photo above) when it is installed. | |
| The Firebox | ||
 | The rear flue sheet is ready for installation. It will be welded rather than riveted to the rest of the firebox. Before the new rear flue sheet is installed, the dry pipe and other throttle parts inside the boiler will be installed. It will be a lot easier to bring them in through the firebox end of the boiler than down throught the dome cap! In the background is a tool used for making fine adjustments to locomotives. | |
 | A view of two flexible staybolts. On the left, the cap has been applied; on the right, the sleeve stands ready to receive the flexible staybolt (which has a ball head) and cap. Many of the original caps are being replaced due to corrosion. | |
 | New staybolts being installed. This view is inside the firebox. Staybolts are threaded through the firebox sheets and the wrapper sheet, then peened over in a manner somewhat comparable to riveting. These will then be seal-welded and a "tell-tale" hole drilled into the center of the bolt. The hole will spray steam if the bolt breaks so it can be discovered and replaced. Every staybolt has been tested, new flexible staybolt caps have been installed, and broken staybolts have been replaced. | |
 | Looking back into the firebox and steam space above from beneath the steam dome. New support brackets will be riveted in, and braces attached to support the backhead when it is reinstalled. | |
 | The lower front corners of the firebox are the areas where boiler scale and mud collect, and consequently often need patching. The inside of the corner has been cut out and will be replaced. | |
 | Once the area has been prepared and the patch tack-welded into place, Jeff Miller (left) and Bryan Behe form the patch to the mudring. When it is the proper geometry rivets, staybolts and final welding will hold it in place. | |
 | The corner is ready for final work. Further work on these corner patches is illustrated below in the "Rivets" section. | |
 | The finished product from outside The washout hole has also been refinished and the threads rehabilitated. | |
| The Steam Dome | ||
 | This is a patch in the boiler course where the steam dome attaches to the boiler. Holes for the rivets which fasten the dome to the boiler were found to be cracked, so this patch (roughly 5 ft. in diameter) was fitted. Bolts hold the patch in place until it can be welded into place; the other bolts, to the right, temporarily hold the internal bracing in place until it can be riveted. This work was quite tedious. The patch had to be perfectly aligned. Then the entire area was preheated before the welding was undertaken. Once the welding was completed, the entire area was swathed in thermal blankets to permit the area to cool slowly without thermal stresses. When everything had returned to ambient temperature, the welds were ground smooth. Finally, the entire welded area was x-rayed and magnafluxed. This entire procedure was carefully documented, as it marks one of the first such repairs permitted under the new 49 CFR Part 230 regulations. In the old days, such a repair would have been impossible, requiring replacement of the dome course instead. Welded repairs on unstayed portions of a boiler were prohibited until the promugation of the new Part 230 regs. Advances in welding technology and inspection techniques have been included to allow for such repairs. | |
 | Another view of the dome patch, looking toward the front of the boiler. Note the chamfering of both the patch and the course in preparation for welding. Welding is permitted under the new steam regulations. Note also that the patch extends to the edge of the course, where it must be riveted to the first course. | |
 | The old dome was riveted into place on the patch. This too was quite tedious because the riveting had to be done from the inside, overhead. So the scale present on the rivets dropped down onto the riveter. Between holding the rivet hammer overhead and the rain of hot scale, the riveter had a difficult task. We had the rivet furnace set up on top of the flat Belpaire firebox, so at lest we didn’t have to carry the rivets far to stick them in the holes. Parts are held together by bolts, which are removed one at a time as rivets replace them. | |
 | The finished repair - the steam dome sits neatly on the flush boiler patch, with all new rivets and dome cap studs. | |
| Front Flue Sheet and Smokebox | ||
 | The superheater header is shown here. The header sits in the top of the smokebox, and the two flanged passageways on the front connect to pipes that deliver steam to the valves. (A third passageway on the rear of the header receives steam from the throttle and dry pipe.) The holes in the "top" (actually the bottom) receive the ball heads of the superheater units. | |
 | The rivet holes shown will be part of the replacement of the lower third of the front flue sheet. This view is looking up at the underside of the boiler; the rear of the cylinder saddle is visible at left. | |
 | The same joint shown from inside the boiler barrel. At the extreme lower left you can see the temporary bolts holding the assembly together; then a series of empty holes (presumably that day's candidates for new rivets); and then completed rivets. Closer to the camera are more tapered bolts holding the smokebox to the cylinder saddle. | |
 | Front flue sheet repairs have been completed and are ready for installation of the superheater header (above). The lower third of the flue sheet has been replaced. The smokebox is all-new as well. | |
| Rivets | ||
 | Jeff Miller drives A hot rivet into place between the smokebox and the first boiler course. It is "bucked over" from inside the smokebox, and will tighten up as it cools. Every rivet was visually inspected, and any found with substantial deterioration was marked for replacement. Several hundred rivets in the boiler courses are being replaced, most of which were severely corroded by the effects of 30 years of outdoor display at Horeshoe Curve. These rivets are 1-1/8 inches in diamter by 4 inches or more in length. The top and bottom third of the rivets securing each course will be replaced. A rivet session requires at least four and sometimes five people. One would heat rivets in a gas furnace. He would remove the rivet from the furnace with tongs and pass the tongs to the "sticker." The sticker would insert the rivet into the hole, and then the bucker would come up against the rivet and start his air hammer. When the bucker started, the riveter on the other side would start his rivet gun, finishing off the rivet with a nicely rounded head. Depending on the location of the work, yet another man would be necessary to pass the rivet from the furnace man to the sticker. If you've never experienced it, you cannot imagine the riot of noise when two rivet guns get going on a boiler! | |
 | The rivet has been heated in the rivet furnace, perched on top of the Belpaire firebox. It's struck to knock loose scale off the rivet before it is inserted into the waiting rivet hole. | |
 | The rivet gun is seated on the rivet and driving begins. Outside the boiler, another crew is "bucking" the rivet to prevent it from popping out of the hole, and to peen over the outside head. | |
 | Riveting is almost complete on the firebox patches. Holes have been drilled and countersunk (so that as the rivet cools and shrinks, it pulls the metal together), and several rivets already driven. | |
 | Walter Elvidge (left) is "bucking" as Jeff Miller drives a rivet. | |
| Studs and tapered bolts | ||
 | Ed Wilt, a Norfolk Southern engineer from Altoona, manufactured more than 100 tapered bolts to fasten the "waist sheets" (which support the boiler on the frame) to the boiler and the frame. In addition, over 100 studs of various diameters and lengths have been manufactured and installed by volunteers. These studs supported the various appliances and appurtenances attached to the boiler -- everything from the air pump and power reverse gear to the running boards and handrail stanchions. Many of the studs were in poor condition, so it was decided to replace them. We had to remove each stud, ream out the hole, re-tap it with new tapered threads, and then machine a stud to fit. The studs were all custom made to fit a specific hole. Each one was stamped with a number corresponding to a number on the boiler. Every single one was hand fit, which often required several trips back and forth to the lathe. When the studs were finally ready for final installation, the threads were smeared with a heavy pitch-like sealant before being screwed in. Then a tool was threaded on to the other end of the stud so that a socket and ratchet could be used to firmly seat the stud. About an eighth of an inch of the new stud protrudes into the interior of the boiler. | |
 | These new studs on the bottom of the boiler barrel will secure the boiler to the "waist sheet," which connects the boiler to the frame. The stud holes are tapered and tapped. | |
 | Most of the new boiler stud holes were reamed and tapped by volunteers. | |
 | The results of Ed's handiwork is shown here. | |
| Miscellaneous | ||
 | This stamp notes a July 29, 1929 repair to the firebox at Juniata shops in Altoona, PA, where the locomotive was built. | |
 | The work force at Juniata shops has signed their repair - a firebox patch from December 1948. | |
 | The drivers have been sent to Tennessee Valley Railroad Museum for repairs to their centers, replacement of at least one axle and turning of the driver tires. TVRM has the only quartering machine in the USA. This machine is used to perfectly align the drivers on the axle so that the crankpins are at exactly 90 degrees to one another. TVRM is also manufacturing two crankpins. |
| A few volunteers have begun work on the tender, though this work has been sporadic. The trucks have been disassembled so springs, links and other components can be inspected and repaired. | |
| More to Come! | |
| More photos can be found at the K4 Restoration Site (click on "latest developments"). | |
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