“Maybe not, but they’ve always had plenty of horsepower and plenty of torque,” chan Hurmahl pointed out. “And the Bison’s suspension and tracks were completely redesigned. All the engineers really used out of the Buffalo was the power plant and the basic chassis; everything else is new, and I’ve seen one of them moving along a prepared surface with a thirty-ton trailer at better than thirty miles an hour.”
Yanusa-Mahrdissa blinked, impressed despite himself. Of course, the army officer was right about the Devil Buff’s sheer power. It wasn’t at the very top of Ram’s Horn Heavy Equipment’s line of bulldozers. That distinction belonged to the Black Rhino, the largest and most powerful bulldozer ever built (yet), but the Devil Buff was no slouch. Like everything else in RHHE’s catalog, it was built “Ram Tough” and its uniflow six-cylinder engine-two banks of three cylinders each mounted back-to-back-produced pressures of up to five hundred pounds per square inch and gave the bulldozer almost sixteen horsepower per ton. The obstacle it couldn’t move was rare, but its maximum speed was no more than ten miles per hour under ideal circumstances, and even then the operator was taking far too many hours off its tracks’ design life.
“When the Army approached RHHE about the Bison, their track designers thought the Quartermaster General was out of his mind,” chan Mahsdyr put in with something suspiciously like a grin. “The Artillery was already experimenting with steam tractors as prime movers, especially for the heavy guns, but Division-Captain chan Stahlyr’s ideas were a lot more…ambitious than that. In fact, I think at least half the Army thinks he’s out of his mind.” The dragoon company-captain shook his head. “He has this idea the entire Army-infantry, dragoons, artillery, and all-should be what he calls ‘mechanized.’ He wants to move everything cross-country as fast or faster than cavalry could cover the same terrain.”
Yanusa-Mahrdissa started to chuckle. Then he realized the company-captain was completely serious and glanced at chan Yahndar, who shrugged.
“It’s not as crazy as it sounds, really, Master Yanusa-Mahrdissa. The Emperor’s been quietly pushing the Army’s modernization for more than fifteen years now. The Empire hadn’t fought a major war in over a century before he took the throne. We’ve been involved in the occasional peacekeeping action, but not against a first-rate opponent, and His Majesty felt we’d allowed our doctrine and thinking to stagnate, especially given the advances in steam engineering TTE’s expansion has been driving. Division-Captain chan Stahlyr’s only about fifty-two years old, but the heads of the Artillery, Cavalry, Infantry, and Engineer Boards are almost as young as he is and they’re all what His Majesty calls ‘forward thinkers.’ He told them to think about Army doctrine and equipment as aggressively as the Navy thinks about designing the next class of battleships, and Division-Captain chan Staylr obviously took him seriously.”
“That’s certainly true,” chan Hurmahl agreed. “He had a pretty damned clear idea what he wanted, and he wasn’t about to take no for an answer. At first, Ram’s Horn told him that if he wanted those sorts of speeds, he should just buy commercial steam drays, but they didn’t have the capacity or the cross-country capability he wanted. So they came up with a design based on a modification of their standard eight-ton dray which is pretty impressive. They call it a ‘half-track,’ since it has a tracked suspension in the rear and steering wheels in front, and it can handle terrain that would kill any wheeled vehicle. They were damned proud of it, because it really is a huge improvement over existing drays, and the QMG was happy to get it. In fact, the Army standardized it as the Halftrack of 5051-the troops named it the ‘Steel Mule’-and ordered over two thousand of them, but it still couldn’t meet his specifications, especially for payload and towing power, since its maximum capacity’s only about a ton and a half, so he sent them back to the drawing board for something better.
“When he insisted he was serious-and they realized he wasn’t going to go away just because it was impossible-they actually looked at the problem. And since they’d been right that no existing suspension could give him that kind of performance, they had to come up with a new one. Once they recognized that, they got into the spirit of the thing, accepted the challenge, and came up with a pretty damned radical solution Instead of conventional leaf springs like the Buffalo’s, the Bison uses vertical springs. The height of the spring well was still too limiting, so they added a bell crank to swing vertical motion to the rear, in addition, which reduced the vertical stroke by about twenty-five percent. The combination means the Bison’s road wheels can displace over twenty inches vertically, and the new springs are actually tougher than the old-style leaf designs. I’ll let you imagine what kind of obstacle that means it can handle.”
Yanusa-Mahrdissa pursed his lips in a silent whistle, and chan Yahndar snorted.
“Don’t let him pull your leg too hard,” he suggested, and the Shurkhali looked back across the desk at him. “Oh, the Bison’s suspension can do everything he’s claiming for it, but the tracks are still more fragile than we’d like. RHHE’s retrofitting the newest design, with rubber backed track blocks, to everything coming down the line behind us, and we’re supposed to be getting an ample supply of spares by the time the main body’s ready to follow us. Unfortunately, we don’t know for certain they’ll get here, just like we don’t know how well the new design’ll hold up. And even if all the new hardware works perfectly, trying to take one of them cross-country at anything like its top speed will jar your teeth right out of your head. The nosebleeds can be pretty bad, too, and if there’s any unsecured gear flying around the black eyes get positively spectacular. And it took some bright lad at Ram’s Horn over a year to come up with the notion in the first place. Then they spent most of another year working out the bugs in the original concept. And they only reached the deployable stage a little over two years ago, so no one has enough experience with them to know whether or not Division-Captain chan Geraith’s idea is really going to be workable.”
“I imagine not,” Yanusa-Mahrdissa said after a moment. “It does make me feel a bit better about the whole notion, though.”
“Like I say, they’re shipping additional units and replacement tracks forward as quickly as Ram’s Horn can get them off the assembly lines,” chan Yahndar said. “And the Mark Two uses kerosene instead of pelletized coal. It’s got a more powerful engine and a longer range, too.”
“How much range are we talking about?” Yanusa-Mahrdissa asked.
“Under decent conditions in open terrain, the Mark One’s good for over two hundred miles on a single bunker of coal, and it carries enough boiler feed water for at least four hundred. I understand the Mark Two will be good for two or three times the Mark One’s range, given the advantages of kerosene. The Mule can make three hundred miles on roads and about two thirds of that cross-country, as long as it’s not too heavily loaded and the going’s not too soft.”
The Shurkhali was impressed afresh. The Devil Buff devoted so little of its volume to fuel, since refueling was seldom an issue, that he would have been astonished if one of the bulldozers could have traveled as much as one hundred miles before refueling. He was less surprised by the feed water endurance, however. The Devil Buff’s coiled monotube boiler used very little water-less than two gallons for the entire system-under very high pressures, and the uniflow engine was downright miserly in steam loss compared to older style expansion engines. And chan Yahndar was right about kerosene’s advantages over coal. Not only did it have a higher caloric efficiency, but a given volume of kerosene contained none of the air spaces between individual lumps or pellets of coal. The powdered coal used in most maritime and industrial power plants had many of the same advantages, but installing the crushing machinery to powder coal on-site in a land vehicle was hardly practical, and Yanusa-Mahrdissa would rather try to transport old-fashioned black powder than pulverized coal. It would certainly be a less explosive challenge! That was the reason the pelletized fire boxes had been developed for vehicular use. The coal was powdered, then mixed with water and a bonding agent and forced through dies which produced uniform pellets about half an inch in diameter. It wasn’t as efficient as injecting the powder directly into the flues, but the pellets packed “tighter,” with smaller air spaces, than lump coal, and they were both easier to shovel and could be fed into the fire boxes mechanically in most cases.