May 2021 #3713 Restoration Update

The restoration of Boston & Maine #3713 at the Steamtown National Historic Site in Scranton, PA has been moving along despite the challenges presented by the pandemic. The Steamtown shop crew was able to safely move the restoration froward, working within the rules set as part of the National Park Service pandemic response. Although 2020 presented many challenges, work continued to bring the steam locomotive – a classic example of American engineering – back to working order after its retirement almost 70 years ago. 

In the months leading up to 2020, the focus was on major parts of the locomotive. The refurbished drivers, brand new tender cistern, newly fabricated cab and other large items all had their turn in the spotlight. The realities of the pandemic saw the Steamtown team focus on smaller assemblies essential to returning the locomotive to order, with one big exception as you will see…

A new custom-built firebox was delivered to Steamtown after construction at the Strasburg Rail Road in southeastern Pennsylvania. The Strasburg team is currently working on thermic siphons for #3713. The firebox will be united with the locomotive’s boiler at the Scranton shop. 

The locomotive’s feedwater pump returned to Scranton after being fully refurbished by the Coffin Turbo Pump Co. of Edgewater, NJ – the very same company that built the pump 87 years ago! The pump is part of #3713’s feedwater heater which uses exhaust steam to pre-heat water from the tender before it is added to the boiler. The resulting increase in thermodynamic efficiency helps the locomotive perform at an optimal level.

#3713 features a trailing truck booster engine to help the locomotive start a heavy train or keep momentum on steep grades. The booster engine is like a miniature version of the large cylinders and valve gear that turn the large driving wheels, but it only powers small wheels in the trailing truck that sits underneath the cab of the locomotive. Booster engines are used at slow speeds to provide extra tractive effort. #3713’s booster will be useful on the Pocono Mountain grades east of Scranton.

Built by Franklin Railway Supply Company and restored under partial contract by Next Generation Steam Services, finished by the Steamtown shop forces, the booster will be a valuable feature of #3713 on the heavy grades leading out of Scranton, PA.

The equalizers for the locomotive’s lead truck were cleaned and inspected by the Steamtown shop crew. After close examination, it was decided to replace them with new material. The old ones will be stored at Steamtown to preserve the original parts. The new equalizers will soon rejoin the truck which has seen a full refurbishment including the addition of brand new wheels, axles, and roller bearings.

The equalizer pins and bushings for the locomotive were replaced because of heavy wear and tear when the locomotive was in regular service. Every piece of #3713, no matter how small, is going through a thorough process of inspection. Any required repairs will be made, or a replacement will be fabricated. No part will go unrestored or replaced.

The coal and water that make #3713’s operation possible are carried in the tender. This is a separate rail car semi-permanently attached to the locomotive. A complete restoration like that being carried out on #3713, requires the entire tender be given the same thorough rebuilding as the locomotive itself.

The bulk of the tender consists of the coal bunker and water tank. The assembly is commonly called the cistern. #3713’s cistern required full replacement. An exact replica was built by Oaks Welding of Ashland, PA. The cistern can’t be positioned on the tender until the trucks, brake rigging, stoker and the frame itself are inspected and repaired. This work was able to proceed during 2020.

The foundation of the tender is a steel frame similar to that found under freight cars. The top of the frame is covered with wood decking upon which the cistern sits, while the bottom carries the brake equipment and center plates that keep the trucks in place. In this image, the frame is turned upside down, allowing the shop crew to work on all the components without having to crawl underneath. Before reaching this phase of restoration, the heavy frame was given the same thorough cleaning, inspection and repair as the rest of the project.

#3713 uses an air brake system compatible with American standards. This means the tender must be equipped with an air reservoir, brake cylinder and rigging to actuate the brakes. The Steamtown team has completed restoration of these components, allowing reinstallation to begin.

#3713’s tender rides on a pair of trucks made by the General Steel Castings Company. These heavy duty trucks were deigned for a smooth ride at high speed. Restoration required both trucks to be fully disassembled with every part cleaned, inspected, repaired/ replaced (if needed) and prepared for service.

When a truck is dismantled, the largest component is the frame. The Steamtown crew used the shop crane to position the frames over the inspection pit, allowing for a full examination of every inch of the frame. Welded repairs are also made with the truck suspended to make access to some inside pockets easier. A truck is made up of a series of sub-assemblies that provide for the transfer of weight from the tender to the rails. A suspension system, brake rigging and the wheels/ axles themselves are all subassemblies that fit together with the frame. The complex design of the truck frame allows these components to all work in harmony with each other.

When assembled, many of the subcomponents of the trucks are held together by weight and gravity rather than rivets and bolts. In this image, the claw- like parts of the casing are where the roller bearing journal boxes will be placed that allow the wheels to rotate. Journals are free to move up and down and are part of a system that helps absorb shocks.

The tender truck journal boxes for #3713 were originally equipped with friction bearings. The boxes were altered by machining in the Steamtown shops, per AAR standards, to accept roller bearings which are housed inside eight journal boxes, one for each wheel. The boxes have been prepared for reassembly and will be combined with the wheels and axles to form one of the many subassemblies of the truck.

The equalizers are familiar components as they can been seen when the tender trucks are assembled. Equalizers sit on top of the journal boxes with downward spring pressure, providing even greater shock absorption. Not often seen are the bolsters, which appear on the left side of the image. Bolsters are floating beams which, support the weight of the tender, and sit perpendicular to the rails. The center bowls provide the pivot for the trucks to swing as the tender goes around curved track.

The bolster is part of a truck’s primary suspension. The large bowls in the bolsters align to the center plates on the tender underframe. A large pin is inserted through the center plate and through the bolster. The center plate helps keeps the truck in place while creating the pivot point required to navigate curves, while the weight of the tender is carried by the center plate. The center plate and bolster pin sit on top the truck, held in place by the weight of the tender.

The ends of the bolster ride on heavy leaf springs that cushion the ride of the tender truck and bear the weight transferred from the tender to the bolster. The springs were reconditioned, replacing the two longer leaves and re-banding of the spring packs.

While the journal boxes and springs compensate for vertical motion, the swing hangars are the part of the suspensions that compensate for lateral forces and help the truck smoothly adapt to curves and track imperfections.

Where sub-assemblies and rigging are attached to the truck frames, a number of different sized small parts to the job. Just like every other part of the trucks, these bits are inspected and repaired or replaced. The parts shown only include a vast number of little machining projects that make up the finished locomotive. Items like these brake head snubbers, fitted bolts, and booster pivot pins, all have to be machined from solid bar stock. Some blueprints exist for these little items but many have to be reverse engineered by the Steamtown machinists and fabricators.

The booster isn’t the only small engine on #3713. Another is located in the tender to actuate the stoker. A stoker is a motorized auger that transfers coal from the tender to the firebox of the locomotives. This saves the fireman from having to shovel coal, which is an enormous task on a locomotive as big as #3713. The stoker motor operates on steam and is controlled by the fireman from the cab of the locomotive.

The stoker motor turns the stoker screw, which moves coal forward as it rotates. The stoker screw and the trough it sits it were rotted beyond use. The Steamtown shop crew decided to have a new screw fabricated by a shop who specializes making conveyor screws. The final machining and fitting will be done by the Steamtown machinists.

Because the tender is only separated for the locomotive during repairs, it is semi-permanently connected via a drawbar. This heavy steel connector attaches to pockets on the tender and locomotive frames. New bushings seen in this picture, and eventually a new draw-bar pin, will be manufactured to keep the locomotive and tender together.

The other end of the tender is where the train is attached, so this is fitted with a type H Tightlock coupler. The extra protrusions on the coupler prevent the cars from becoming uncoupled in case of a derailment. #3713 donors paid for an all-new coupler which will serve the locomotive well no matter what kind of train it is pulling.

Please keep checking this site or for more updates as the restoration proceeds.