Q: To approximate the number of cranes worldwide with lifting capacity
of 10 tons or more.

Here is an example of my findings:
I took a quick look at Konecranes? financial reports.  Konecranes is
one of the leading makers of cranes (others include Manitowoc,
Sumitomo, Liebherr, Mitsui Engineering & Shipbuilding; see also
http://www.globalspec.com/industrial-directory/Crane_Manufacturer/ for
many more manufacturers).

Kone claims a global market share of 10%, based on sales dollar
volume.  Interestingly, their 2003 financial report, with respect to
their maintenance service contract base, states ?The net growth in
terms of number of cranes included in the contract base was 0.7 %. It
grew to 209,769 (208,270) units at the end of 2003.? If Kone is
servicing 200K cranes and their general market share is 10%, it seems
reasonable to assume that there are 2 million cranes worldwide.

I would appreciate if someone can itemize the makers and units
sold/market share of the major players to determine the number of
cranes out there with a capacity of 10 tons or more