Hi: When we had extremely cold temps, I used to use quick connects to my truck and equipment similar to those shown. We used to pull into the landing, plug in the crawler to the truck, have some coffee or do some chores, while the crawler engine warmed (and the truck engine cooled) from the transfer of coolant, then start it on its way into the woods. Then we would repeat with the skidder. This gave the chopper a head start on the day and some comfort knowing that the machines would at least start. On less cold days, we left the crawler in the woods, started the skidder off the truck, and then brought the hoses into the woods then used the skidder to warm the crawler, and the day officially began. The hoses were about 10 feet long which reached easily between the different sized machines.
I was concerned about sharing the coolants, but I serviced my machines regularly and there was never an issue.
I used hydraulic hoses since they were available and I used spare screw-in type Parker fittings. Today I'd look for a less expensive option since the coolant pressures are low.
Fun to reminisce - and I know what Rube Goldberg means, both literally and figuratively.

Paul
Rube Goldberg, creative solutions to immediate challenges:
http://www.google.com/imgres?start=233& ... :200,i:193