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Students devise, fabricate cannon transporter for Civil War

“Custom fabricating is all about working from knowns to unknowns,” said hobby fabricator, professional fabricator, welding instructor, and lifelong horsepower enthusiast Mark Prosser. As a youngster, his playground was his father’s garage and back yard, where the elder Prosser owned and operated an auto repair and restoration shop. Through his childhood and teenaged years, Prosser built or modified more than his share of minibikes, go carts, and snowmobiles. It was quite an apprenticeship, later fortified with a degree in welding technology from Ferris State University, Big Rapids, Mich. Prosser then earned a bachelor’s degree from Central Michigan University, Mt. Pleasant, Mich., followed by a master’s degree in adult education in 2013. An instructor for nearly 15 years, he continues to fabricate in his free time, dedicating many evenings, weekends, and holidays to projects of all sorts.

Although he never thought he’d modify a school bus, he was ready when an opportunity came along. He worked on the project with another welding instructor, Jeremiah Johnson, a fifth-generation steamfitter. Under the guidance of Prosser and Johnson, a select group of students turned an ordinary school bus into a feat of engineering.

Hundreds of Battles, Hundreds of Miles

The members of Battery G, 2nd Illinois Light Artillery had two cannons, an old school bus, and a lot of miles to cover to participate in mock battles. A team of Civil War reenactors, they had discarded their previous bus—which they had modified themselves to carry the two cannons—and needed to transform their new bus. Their original system was serviceable, but for their new cannon transporter, they wanted a system that would be heavier duty and easier to use than their previous bus. They enlisted the help Prosser, Johnson, and students at Blackhawk Technical College (BTC), Janesville, Wis.

The task sounded straightforward. The bus’s dimensions, horsepower, and payload capacity were enough to handle two cannons and two limbers (the boxes used to store gunpowder and ammunition). The BTC team wouldn’t have to beef up the suspension, make any modifications to the engine or frame, install a larger radiator, or anything like that. The Civil War reenactors just needed a system for getting the cannons onto and off of the bus. The team had kept the 8,000-pound winch from the original bus, so the BTC team had no questions as to where the power would come from to pull the cannons into the bus.

Knowns. Because the reenactors had the cannons and the bus, Prosser and his students had a starting point. However, the first set of knowns concerned the factors that were detrimental to loading, unloading, and hauling a couple of cannons and limbers.

First, an unladen school bus is pitched.

“When the bus is empty, the back end sits higher than the front end,” Prosser said. “They’re designed this way so they sit closer to level when they’re full.” Removing the seats reduced the total weight, making the back end rise a little more. Battery G’s original ramps were lengthy to deal with the high back end. Lowering the back end would be ideal, reducing the ramp angle and thus the effort required to haul the cannons into the bus.

Second, a school bus floor—a layer of plywood over a layer of sheet metal—is fine for the combined weight of 44 seats and 88 children distributed over the entire surface, but it’s not intended for 6,000 lbs. concentrated at six points. It would need to be replaced.

Third, a bus floor is flat except for the tubs that cover the rear wheels. As luck wouldn’t have it, the distance between the rear wheels on a school bus is about the same as that of a Civil War-era cannon. The members of Battery G had used ramps to get the cannons up and over the tubs, but even so, it wasn’t an easy task. Getting them in wasn’t too bad because the electric winch provided the power, but it took a lot of muscle to get the cannons out.

Last, the rear door on a school bus is just wide enough for a person, not a cannon. The team would have to cut off the back of the bus and create two new doors that would span the width of the bus.

Figure 1
Before cutting off the back end of the bus, BTC staff and students secured it to a crane (not pictured). Two additional straps, each manned by a helper, were used to guide it as it was lifted away from the bus (left). After removing the floor, the student fabricators were ready to begin the assembly phase of the project (right).

Unknowns. Although the two instructors and the students had quite a few knowns to work with, they still had to deal with a handful of unknowns before making the first cut. Some were easy to work out.

“After a few discussions, the reenactors voiced some concerns about the total weight of the material we planned to use,” Prosser said. “The factory tag states the gross vehicle weight rating, and we Googled the bus weight, and they had already told us the weight of the cannons. We came up with an approximate weight of 6,000 lbs. for both cannons and limbers, give or take a few hundred pounds.”

Most of the unknowns took some time to resolve.

“This project lasted about nine months,” Prosser said. “It wasn’t nine months of continuous work, but a practical application that took the students out of the welding booths and gave them a chance to work on a real project and learn how it all works together.

“We’d go out and look at the bus, and we’d talk about making ramps, and the advantages and disadvantages of securing them with pins, and eventually we’d make a decision.” Later, they’d discuss another component, and under the guidance of Prosser and Johnson, they would work through the various factors such as: strength, ease of use (disassembly and assembly, if needed), and where and how to stow or store components when not in use.

Some of the unknowns concern material strength, but Prosser and Johnson don’t have any trouble turning those sorts of unknowns into knowns. “You can find formulas to figure out anything,” Prosser said. “And if you can’t find them, overbuild!”

The many discussions led to several design concepts, and eventually a plan emerged. It became clear that the rear bumper would be the most critical component.

  • The original door would have to go (see Figure 1). It was just an access door, wide enough for one person at a time to pass through (two in an emergency). The team would remove the back end of the bus and fashion a pair of custom-made, barn-type doors that would span the bus’s width. The bumper would keep the tail end of the bus in good alignment, true and square, which in turn would allow the doors to open and close without binding.
  • Although the team would leave the chassis intact, the area behind the rear wheels would be dovetailed similar to a car trailer. This section would be removed and rebuilt with a downward pitch (see Figure 2). In other words, in the area behind the rear wheels, the bus floor would become a built-in ramp. This would lower the rear bumper by 20 in. or so, meaning the ramps for the cannons would be much shorter and lighter, and therefore much more manageable than before. The bumper would be the main point of strength for the ramps and doors.
  • The ramps would have to support 3,000 lbs. of cannon at a time. They would be fastened to the bumper, so the bumper would need to be robust enough to withstand this much weight.

So it went, eliminating one unknown at a time. In addition to working through each phase, Prosser and Johnson focused on keeping the momentum. Projects need to be managed to meet deadlines—a critical part of any project that is easily overlooked, Prosser said.

“The best project in the world has to be completed at some point,” he said.

When a new unknown emerged, some of the students couldn’t resist the temptation to re-evaluate the previous step—that is, a finished step. Thoughts about re-doing previous steps don’t make good use of time or brainpower and impede progress more than anything else, so the instructors were vigilant and always ready to eliminate such idle musings.

Figure 2
After removing the floor, the student team created a new bumper that would act as an anchoring point for the ramps and the door. Because the new bumper is much lower than the original bumper, the ramps are short and light, and therefore easy to handle.

“We’re done with that step—we’re moving forward, not backward” is a phrase Prosser used often. Eventually it became evident that, although it would take a lot of work—hundreds of hours by Prosser’s estimate—a school bus is nearly ideal for hauling a couple of cannons around. The chassis is reinforced with cross members spaced about every 48 in. or so. These cross members, made from 3- by 3-in. square tubing, provide quite a few points for anchoring things to the bus. The team removed the original floor to expose the cross members so they could use as many of the original frame holes as possible; new flooring made from channel, square tube, plate, sheet metal, brackets, and all other components would be bolted to the chassis, then welded in place.

In all, the bus needed three ramps: one for each wheel and one for the trail, which is the portion of the carriage that rests on the ground.

“The students decided to use C-channel,” Prosser said. Such a channel is intended to be a structural element, normally installed with the open side facing left, right, or downward so it doesn’t collect water and rust. In this installation, it would be installed upside down.

Would they have enough strength to do the job? Of course. You can find a formula for anything.

The remaining difficulty was a matter of getting the cannons up and over the wheel tubs. Using muscle power to get the cannons out of the bus was a challenge, and it got worse as time went on. Several days of summertime battle reenactments in replica wool uniforms can wear a soldier down. The members of Battery G were more than a little dazzled when the BTC team showed them the new removable wheel tubs. Remove two bolts, remove the wheel tubs, pin two ramps into place, and presto! The cannons roll right in.

Like the rest of the components, the winch is more secure in this bus than in the original bus. The reenactors had drilled holes in the floor and secured the winch with large-diameter bolts, nuts, and washers. It worked, but it put a lot of tension on floor. The new winch base is built from 3⁄8-in. steel plate situated and installed with welds and hardened bolts through the factory frame holes, effectively making it part of the bus’s chassis (see Figure 3).

Close attention to detail on the part of the BTC staff made the winch easier to use. Because the cable tends to build up in the center of the drum, one of the reenactors would put on a pair of gloves and guide it manually back and forth to distribute it evenly. Difficult and dangerous, this task now is performed by a steel bar on a pivot. The reenactor merely moves the bar left and right to guide the cable back and forth.

Ready, Aim, Fabricate!

A classroom is a clean, controlled, somewhat sterile environment in which all of the variables are controlled, all of the workpieces are clean and rust-free, and all of the welding projects are planned well in advance. This project didn’t have any of that.

“We need to try to duplicate what they’ll experience in industry,” Prosser said. In a high-volume manufacturing environment, particularly at the OEM level, the emphasis is on productivity and efficiency, so keeping tight control over welding variables and the process is critical. However, in the high-mix, low-volume world—that is, custom fabrication, field welding, and repair welding—it’s hard to say what the students will encounter. Experience like this is a key component in making sure they’re really prepared for the workforce.

And while it isn’t likely that they’ll encounter this sort of project anytime soon after graduation, they’ll already have a sense of how the whole process works from design to research to ordering materials to managing tasks to completion. They’ll also have some experience in overbuilding a project, if that should ever come up.

Figure 3
While no part of a complex assembly is more important than the others, the winch bracket warranted a little more attention than some other items in the cannon carrier. It would have to withstand all of the tension the winch developed when pulling the cannons up the ramps.

An Unknown Known?

The BTC team also worked with a known that turned out to be an unknown. The weight of a single unit, one cannon plus limber, was confused with the weight of two cannons plus two limbers. To be fair, this isn’t the first team that had such a discrepancy, and it won’t be the last. Imperial units can get mixed up with metric units, a foot-pound can be interchanged with a pound-foot, and, well, anyone new to the pipe industry has to be wary to distinguish between nominal pipe sizes and the actual ODs.

In the case of the cannon carrier, the substitution of one weight for another turned out to be a fortunate mistake. Rather than estimating a 6,000-lb. payload and outfitting the bus accordingly, the rig is heavy-duty in that it was designed to handle 12,000 lbs. This isn’t necessarily a factor regarding normal operations and expected driving conditions—the accelerations and decelerations are gradual, at best, and aren’t likely to shake anything loose—but the total weight would be a factor in a collision or a rollover. Nobody wants thousands of pounds of cargo tumbling down the roadway, and the folks at the National Highway Traffic Safety Administration tend to take a dim view of modifications, but the BTC staff is confident that the members of Battery G have nothing to worry about.

“I can’t imagine any traffic safety engineer examining that bus and saying, ‘You should have made that stronger,’” Prosser said. “You’d have to break the bus’s frame to rip the cannons out.”

As far as liability, the two groups seem to have struck a balance. The reenactor group signed a waiver, and the BTC team overbuilt the bus. In other words, the reenactors have the liability, but it seems to be negligible.

“This project is probably five times overbuilt,” Prosser said. “That is the nice thing we can do when profit is not in the equation.”

In return for all the labor, Battery G made a generous donation to BTC’s student chapter of the American Welding Society, which is organized and overseen by the night shift welding instructors, Dan Crifase and Bobbi Jo Bishofberger. Donations enable the chapter to fund field trips, cookouts, and recruiting events, but this isn’t all that they gained from the Battery G project. The instructors and the students also gained something that can’t be measured: experience that comes from working on a real-world project.

“It’s the best way to learn this trade,” Prosser said. º

Mark Prosser and Jeremiah Johnson are welding instructors at Blackhawk Technical College, 15 Plumb St., Milton, WI 53563, 608-758-6900, www.blackhawk.edu.

Protecting Priceless Artifacts

The 12-pound cannon is so named because it fires 12-lb. balls, but these weren’t the only projectiles it fired. In the middle of the 17th century, other typical ammunition included shells filled with individual projectiles (shrapnel shells), pairs of balls linked by lengths of chain (chainshot), and canisters filled with steel balls (canister shot). In 1795, four years after the start of the French Revolution, rising star Napoleon Bonaparte put an end to a royalist insurrection—solidifying the Republic’s place in France and his place in history—by dispersing the royalists with “a whiff of grapeshot” (small steel balls packed into canvas bags). Redesigned years later, the 12-pounder was nicknamed the Napoleon Cannon after Louis-Napoleon Bonaparte (Napoleon III), nephew of Bonaparte. Approximately 3,000 were cast on this side of the Atlantic during the Civil War era.

The reenactors of Battery G, 2nd Illinois Light Artillery are some of the few and very fortunate reenactors to have authentic artillery pieces—not just one, but two—of the 300 or so that remain.

Figure 4
Finished! The floor acts as an internal ramp; the bumper provides securing points for the external ramps and doors; and the doors allow Battery G to use the entire width of the bus to stow and transport its cannons.

“They used to fire them [for demonstrations], but they had to have ultrasonic tests done on them” periodically to verify their integrity, Prosser said. “When they were fired with a full load of powder and a 12-lb. ball, the entire cannon would recoil about six feet,” he said.

Because live firing with a full load of gunpowder—2.5 lbs.—puts too much stress on a casting that is more artifact than armament, one whose age and rarity make it essentially priceless, most of the originals have been put on light duty. During mock battles, they are loaded with just a 20 percent charge of gunpowder, which is more than enough to make an authentic-sounding explosion.

The bus provides protection for the cannons during transport. The Blackhawk Technical College team provided anchoring points for the cannons and went a step further in incorporating tubes that span the width of the bus. The tubes divide the bus’s interior into three zones—one for each cannon and one for the driver.

It’s gratifying to know that these prestigious relics are transported in a bus that is more than capable of protecting them.

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Eric Lundin

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Eric Lundin worked on The Tube & Pipe Journal from 2000 to 2022.