Why do trucks fail on an uphill climb?

Hello everyone,

I live in Washington State and on my commute to work drive through an area called Tiger Mountain. If you search the internet for "semi truck tiger mountain" or similar terms you'll see some pretty gnarly stuff.

Today on my way up to the summit (1,477ft) there was a stalled semi truck in the right lane with it's hood popped open. I'd say this happens once a week or at least a few times a month, though I don't always see it.

What kind of things do trucks need to be aware of on the uphill and what kind of things fail? What kind of experiences have some of you had on hills?

I could see he had plenty of transmission fluid and coolant. Sometimes the trucks are run down O/O's but today's actually looked in pretty good shape running a Walmart trailer.

Hope this isn't a dumb question. Just looking to hear from experienced drivers on this topic.

 

Good point. I think you're right. I'm not very mechanically inclined and believe I was mistaking one of the reservoirs as transmission but it's not.

So before you're going up hill or as you're going up hill are there certain things you worry about?