To The Stars

“Brake drum heat on cars seven and eight. What the devil can that mean? All brakes are off.” Jan muttered savagely to himself, things had been going too good, and leaned forward to press the readout button. Numbers appeared on the screen. Up over twenty degrees on both those cars — and still rising.”

He thought quickly. Should he stop and investigate? No, that would mean halting the entire line of trains, then getting them moving again. There were at least 300 kilometers more of desert road before they hit the foothills, and he wouldn’t be needing brakes at all until that time.

“Kill the brake circuits in both those cars and see what happens,” he said.

Otakar hit the switches while he was still issuing the order. Now the two cars no longer had operating brakes, but the safety circuits should have gone dead in the off position. They did. The temperature in the brake drums dropped slowly until, one after the other, the red lights went out.

“Keep the con,” Jan said, “while I see if I can figure out just what the hell is going on.” He went to the rear and threw up the cover of the hatch down to the engine compartment. “Emo,” he called through the opening. “Pass me up the diagrams and manuals on the car brake circuits. We have a problem.”

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.”