Jan had done maintenance on the brake systems, as he had on all of the machinery, but had never needed to break down and repair one of the systems. Like all the Halvmork machines, these had been designed to, hopefully, last forever. Or as close to that as possible. With replacement supplies light-years away, rugged design was a necessity. All components were simply designed and heavily built. Lubrication was automatic. They were designed not to fail under normal use and, in practice, rarely did.
“These what you want?” Emo asked, popping out of the hatch like an animal out of its den. He had diagrams and service manuals in his hand.
“Spread them out on the desk and we’ll take a look,” Jan said.
The diagrams were detailed and exact. There were two separate braking systems on the cars, each with its own fail-safe mode. Normal braking was electronically controlled by the computer. When the engine driver hit the brake, the brakes in all the cars were applied at the same time, to the same degree. The brakes themselves were hydraulic, the pressure coming from reservoirs that were supplied by pumps turned by the axles of the car. Strong springs held them in the normally off position. The electronic controls opened the pressure valves to apply the brakes when needed. This was alpha, the active braking system. Beta, the passive one, was for emergencies only. These completely separate brakes were held in on position by their springs until the electric circuits were actuated. When this was done powerful magnets pulled them free. Any break in the electrical circuits, such as an accidental uncoupling of the cars, would apply these brakes for an emergency stop.
“Jan, two other trains calling in for advice,” Ryzo said. “Sounds like the same trouble, temperature rise in the brakes.”
“Tell them to do what we did. Cut the power to the alpha systems. I’ll get back to them after I track down the malfunction:’ He traced the diagram with his finger. “It must be the alpha brake system. The emergencies are either full on or full off — and we would certainly know if that happened.”
“Electronics or hydraulics?” the engineer asked.
“I have a feeling that it can’t be the electronics. The computer monitors all those circuits. If there were an uncalled for on-brake signal it would negate it, and if it couldn’t be cut the computer would certainly report it. Let’s try the hydraulics first. We’re getting pressure in our brake cylinders here. The only way we can get that is if this valve is opened slightly—”
“Or if something is blocking it so it can’t close completely.”
“Emo, you’re reading my mind. And what could be blocking it is just plain dirt. The filter in the line here is supposed to be cleaned out after every trip. A nasty, dirty job, crawling around under the cars. A job I remember assigning to a certain mechanic named Decio some years ago. A mechanic so bad that I eventually demoted him right back to the farm. When we stop we’ll drop one of those filters and look at it.”
Emo rubbed his jaw with a calloused hand. “If that’s the trouble we are going to have to drain each malfunctioning brake system to get the valves out to clean.”
“No need. These emergency valves, here and here, shut tight if the line is broken. We won’t lose much fluid. There are spare control valves in stock. What we’ll do is replace the first valves with new ones, have the old valves cleaned while we are working and exchange them right down the line. The grades aren’t too bad this first day; we’ll leave the brakes cut out on the few cars with trouble.”
“Jan,” the co-driver called out.“‘Mountains in sight, so the tunnel will be coming up soon. Thought you would want the con.”
“Right. Leave the specs here, Emo, and get back to your engine. We’ll be hitting the slope soon.”
Jan slid into the driver’s seat and saw the sharp peaks of the mountains ahead, stretching away, unbroken, on both sides. This was the range that kept the interior of the continent a desert, holding all the storms and rain on the far side. Once through the range they would find weather again. The Road ahead began to rise as they entered the foothills. Jan kept the autopilot on steer, but released the other controls. As the slope grew steeper he let up on the accelerator and dropped into the central gear range. He could see the Road rising up ahead and there, above, the dark mouth of a tunnel. He switched on his microphone.
“All drivers. The tunnel is coming up in a few minutes. Headlights on as soon as you spot it.”
He switched on his own lights as he said this and the Road ahead sprang into harsh clarity.
The engineers who had built the Road, centuries earlier, had had almost unlimited energy at their disposal. They could raise islands from the ocean — or lower them beneath the surface, level mountains and melt solid rock. To them, the easiest way to pass the mountain range was by boring straight through it. They were proud of this, too, for the only decoration or non-functioning bit of the entire Road was above the tunnel entrance. Jan saw it now, cut into the solid rock, as the dark mouth loomed closer. A hundred-meter-high shield. The headlights caught it as the Road straightened for the Final approach. A shield with a symbol on it that must be as ancient as mankind; a hand holding a short and solid hammer. This was clear, growing larger, until it swept by above and they were inside the tunnel.
Rough stone wall flashed by gray and empty. Other than the occasional stream of water that crossed the Road, the tunnel was featureless. Jan watched his tachometer and speedometer and left the steering to the autopilot. Almost a half an hour passed before a tiny light appeared ahead, grew to a disk, then a great burning doorway.
They had gone far enough south, and risen high enough, to have driven into the dawn.
The massive engine tore out of the tunnel and into searing sunlight. The windshield darkened automatically at the actinic onslaught, opaquing completely before the sun. Beta Aurigae was blue-white and searingly hot, even at this northern latitude. Then it was obscured by clouds and a moment later dense rain crashed down on the train. Jan started the windshield wipers and switched on his nose radar. The Road was empty ahead. As quickly as it had begun, the storm was over and, as the Road wound down out of the mountains, he had his first view of the acid green jungle with the blue of the ocean beyond.
“That’s quite a sight,” Jan said, hardly aware he had spoken aloud.
“It means trouble. I prefer the inland driving,” the co-driver, Otakar, said.
“You’re a machine without a soul, Otakar. Doesn’t all that twilight monotony get you down at times?”
“No.”
“Message from the forward Road crew,” Ryzo called out. They’ve got a problem.”
Otakar nodded gloomily. “I told you, trouble.”
Six
“What’s happening,” Jan said into the microphone.
“Lajos here. No big problems clearing the Road until now. Earthquake, at least a couple of years ago. About a hundred meters of Road missing.”
“Can’t you fill it in?”
“Negative. We can’t even see the bottom.”
“What about going around it?”
“That’s what we’re trying to do. But it means blasting a new road out of the cliff. It’s going to take at least a half day.”
Jan cursed silently to himself; this was not going to be an easy trip at all if it continued this way. “Where are you?” he asked.
“About a six hour drive from the tunnel.”
“We’ll join you. Keep the work going. Out.”