I haven't been able to find a single dictionary definition specifically for the phrasal verb "crank along". It has a meaning of its own - it's not a synonym for crank, crank up or crank out, but it doesn't seem to be in the dictionaries.

Here are two references from the web, the first talking about computer nperformance, the second from a translator talking about his (or her?) own performance. Although forums (sorry, I dislike the word fora) and blogs are dubious references, both of these are very well-written.

I am working on a one computer solution and wonder if anyone has had any
success?

My existing setup cranks along okay, albeit at 80-95% CPU load until I try to
run pmInstructor. This fantastic program pushes my system over the edge
and locks the program up.
http://www.mycockpit.org/forums/showthread.php?t=4305

Phone calls and faxes can interrupt the flow I get in once I start on a text, so I all but guarantee myself a couple of hours in which, except for rare cases, I can crank along at a steady, productive pace.
http://blog.beswandjarum.com/hanifgenangsetyaji/

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Note added at 4 hrs (2009-06-22 14:19:39 GMT)
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So, something that cranks along, goes along (ie progresses) normally. Not spectacularly - it's not a very positive verb - but it goes OK. It's often associated with something a bit old, out-of-date, last year's model which still works sufficiently well that you don't feel the need to replace it yet.