Why is it many newer patents, such as in US10421637, A cranking mechanism, the independent claim 1 is almost entirely repeated in claim 8, except for a small change? I do not find this in older patents.
I'm not a lawyer but I've worked with several on my patents. There is a lot of art in drafting claims and I don't think this is a particularly new phenomenon. Claim 1 and 8 are not identical. In particular:
From claim 1: "...a clutch is retained on said crank shaft, said clutch includes a drive gear;..."
From claim 8: "...a clutch is retained on said crank shaft between said one way bearing and said tightening device, said clutch includes a drive gear;..."
I often see this pattern of having slightly narrower versions of independent claims. There must be a legal reason. Perhaps a patent attorney or agent will comment on that.
I often write claims that might cover essentially the same thing but in different language. It is some protection from a court that might misconstrue some word or wording in one of the claims. Depending on how old the patents you are comparing this with, they might be from a time when “ a portion of “ included a whole of, when “one or more” was never interpreted as excluding the case of one and when “and” never meant “or” (I’m a patent agent). We now need defensive claiming.
Another speculation relates to the series of “Festo” cases. The importance of this has faded but this series of cases said that the breadth of interpretations of a claim was significant reduced if that claim was ever amended. Adding a slightly different claim rather than amending a claim might have made sense.
This is an answer regarding U.S. practice.
Possibility one: the applicant wants as many patents as possible for an invention with the aim of gaining bargaining power in negotiating cross-license or a patent pool. As you may know, the number of patents a party has is one of the critical factors to determine how much money s/he can get from the license negotiation or a patent pool.
Possibility two: The applicant may want to avoid the "double patenting" rejection but at the same time want to keep the application alive (pending) by repeating divisional applications in order to amend the claim according to the market condition.