The big yellow truck leaned over distressingly as it pulled onto the shoulder of the highway. The boy looked at his dad curiously, and asked “Why are we stopping?”
His father sat quietly for a moment, surveying the scene in front of them. Through the windscreen, they could see forever. Range after range of mountains, piled up one behind the other, stretched into eternity, dark close up, but fading to the colour of the grey sky in the distance. To their left, on the other side of the road, was a railing, and the ground simply vanished beyond it. It was breathtaking, even to a child.
“Well, first, because of this amazing view,” said his Dad, “and secondly because you’re going to have to go ride with your mother and sister now.”
The boy was stunned into silence. He had travelled at the side of his father for thousands of kilometres, had been a faithful and competent navigator following closely on the map their traverse of the the great country. He didn’t understand why now, at the last, he’d have to be relegated to the car.
“Why?” he asked. His eyes were wet with tears.
His father sighed and unbuckled his seatbelt. He slid across the bench seat and put his arm around his son’s shoulders.
“Well, my boy. Take a look out that window. See how the road goes down so steeply?”
He looked, and saw that the road did drop precariously from there. He nodded and leaned into his Dad’s side.
“That road goes down to the town we’re going to live in. It goes really, really far down. We are currently sitting on top of something called ‘The Continental Divide’. That’s a ridge of mountains that run down North America, sort of like a spine. It’s really high up. This road ahead of us is called ‘Kicking Horse Pass’.”
The boy giggled and asked why is was called that.
“Because a long time ago some crazy old guy got kicked by his horse here.” he father answered.
The boy visualized this, a man getting kicked off the cliff over to their left and falling down, down to the bottom. In his mind’s eye, he saw the man splash into a river, then surface, sputtering and shaking his fist up at the top of the cliff where his horse stood chewing grass slowly and regarding him with malice. He laughed again.
“But why do I have to go with Mom?” he asked.
“Well, like I said, we’re really high up. And we need to go really far down to get to town. That’s not really a problem. The problem is this truck, and specifically its brakes.”
The boy thought about this a moment, but his seven year old mind couldn’t really put the brakes and his exile to the car with ‘the girls’ in to a single coherent thought. His father continued.
“As the truck starts going down the pass, I am going to have to slow it down, and that means using the engine and gears. The hill is so steep that the engine and gears alone can’t slow the truck down, because it’s too heavy so I’ll have to use the brakes too. And that’s where the problem is. The brakes on this truck are okay for driving across flat ground, but on a hill like that, they might overheat. This is a very heavy truck. Do you know how the brakes work?”
The boy slowly shook his head, trying to build a mental model of all the things his father was telling him.
“You know how I told you once that energy never goes away, it just gets changed from one type of energy to another? Well, that’s how brakes work too. They change the motion of the truck into heat, and then that heat is transferred to the air around the brakes to keep them cool, so they can keep changing the speed of the truck into heat. And if they get too hot…”
“Then they can’t slow the truck down!” the boy answered. He suddenly understood. “But why does that mean I have to go with Mom?”
“Because it could be dangerous. If the brakes stop working, I won’t be able to slow down the truck enough, and there could be an accident. And you’re far too precious to risk,” his father answered.
The boy’s lower lip started trembling. He understood. There was nothing he could do, and he’d just have to accept that the descent into the town they would call home would simply have to happen with him in the car, not the truck. He sighed a great, shaky sigh, and turned toward the door of the big yellow truck. His mother was already there, wearing a concerned look on her face. She opened the door, unbuckled his seatbelt, and picked him up.
“What’s wrong, sunshine?” she asked, cradling him against her and rocking gently.
“I’m okay, Mom” he answered, then wiggled until his mother put him back down on the bench of the seat. He turned around and hugged his father tightly. “Will you be okay Dad? Will everything be okay?” he asked.
His father hugged him tightly to his chest. “Yes, boy. Everything will be okay. It’s just a precaution. I’ll see you at the bottom of the hill, and we’ll ride into town together, okay? There’s a restaurant at the bottom of the hill that sells pizza, and you know what? They put pineapple on it! Isn’t that awesome?”
The boy brightened at this thought. “Pineapple? That’s weird!”
“Time to go, little man,” his mother said, and picked him up again. She walked him back to the car and buckled him in among the houseplants. Then she walked back to the truck.
“You look like you’ve been crying,” his sister said.
“Maybe. But I know something you don’t,” he answered, “I know about pineapple.”