I have attached a picture of a log grab. Hopefully the picture will show its size and configuration.
When the hook is driven into the log, the way it is forged, the chain attached at the other end lifts up and sort of keeps the log grab on a bind. The upward lift as the horses move forward keeps it in place.
Once I get to the landing, I can knock the hook out by lifting on the little ear behind the hook. A peavey works well for this, but I usually just give it a good crack there with my grab hammer.
Perhaps a pictorial and article with more details is in order for an upcoming RH issue?
For now, I hope this helps.
