Finding a suitable English translation of "An old donkey pulls all the weight all alone"

A Hungarian colleague of mine just impressed upon me the idiom

An old donkey pulls all the weight all alone.

The phrase itself isn't a common English idiom (not to my knowledge, anyway). I think in the translation from Hungarian it has become... well, not less eloquent, but perhaps less English. Though hearing it in context I felt it was an apt metaphor.

To provide some context, my colleague is talking about the fact that as the senior member of the team he feels like he expected to cover for the less senior members' mistakes. In this sense, he is the old donkey pulling the weight of the others.

I was trying to come up with a similar phrase in English which describes the same situation that would be more familiar to English speakers, but I am at a loss.

Is there a widely recognised idiom that represents the struggle of feeling all alone unable to rely on the people around you, even with a team/family/group who should be helping or supporting you?

A related saying might be, "If you want something done right, you have to do it yourself." It definitely has the connotation of not being able to rely on other people (particularly subordinates) to do something. But it doesn't really imply that therefore all the work falls on you.

These aren't idioms I've heard, but how about:

"The older the horse, the heavier the burden"

Or to reverse the idiom of "The chain is only as strong as the weakest link", you could say:

"The strongest link in the chain has to hold the others together"

If I haven't answered it correctly, I at least hope I've gotten close.

"It's lonely at the top", possibly?

A vaguely comparable English catch-phrase is, "If you want to get something done, give it to the person who's busiest." The idea being, people who are competent and industrious tend to take on all the work, and people who are sitting around doing nothing are often in that position because they are either too lazy to do the work that's given them or because they are so unreliable that no one trusts them with any important work.