This is from
Mansewerz's Guide to Stringing Machines (it's worth reading):
"Cranks-Cranks, aka Lockout machines, are a tensioning mechanism that uses a pre-loaded spring to determine when proper tension is reached. There is a crank, that has a built in brake/locking mechanism. The stringer turns the crank until the tension is reached, then the brake is engaged and no longer allows the stringer to turn the crank, and then that string being tensioned is clamped off. The stringer then disengages the brake and tensions the next string.
The mechanism is known as a "lockout" mechanism, which is why cranks are also known as "lockout" machines. Cranks are typically the fastest tensioner, but require more physical work than electronics or automatic dropweights. Note: When I say faster, I mean that they are able to tension strings more quickly. You should not turn the crank at full speed to quickly tension the string. A slow, consistent speed gives the most accurate results."
People will argue all day long about Constant Pull, which is what (most) electronic and all drop-weight machines are vs Lock out.
Supporters of CP will say it's a more "true" or more "accurate" tension. I've come to the conclusion that neither is better. They're just different.
Many many stringers will tell you that what it's all about is consistent technique. In other words, regardless of machine, if you have the same racuet, same strings, same tension, etc... then the results should be the same every time.
A Fischer Pro One 98 strung with Forten Sweet Synthetic Gut 16 at 60lbs on a Mutual Power Titan 7700 (crank) machine should have the same resulting string bed every time you do it.
And while that same setup may have a slightly different string bed if you used an electronic or a drop-weight, the more important point is that if you use the same machine-type each time you string, you results should be consistent.
This is possible with crank, it's possible with electronic, and it's possible with drop weight.
But again, there will be no end to the debate.... because that would make life boring!