This is the model of a 40 tons Figee level luffing shipyard crane, built during 2012 and 2013. The model is 2,7 m high, and weighs about 13 kg, excluding the counterweight.
Below are some details.
The crane is driven by two XL PF motors through big gear reductions. This made it very slow and still the motors were tripping after some time. I could only test this when the crane was fully assembled in my garden (it did not fit anywhere in the house), but then it was too late to make improvements.
In this photo the top of the crane is removed to make the slewing gear visible. The motors and the gearing cab be seen. The tipping moment is transmitted by pulley wheels (with tyres on) to the inner rim of the droid gear wheel. The weight of the upper part is carrried by a turntable, which act as a thrust bearing on top of the portal of the crane, just as in reality.
Both hooks have their own winch, medium PF motor driven. The winches are similar. The auxiliary winch is seen here:
The ropes are silk kite wire and run over pulleys which are drilled out to make them revolve independently over the same axis.
The jib tip and the main hook.
The luffing gear, driven by an XL motor.
The counterweight consists of boat weights and lead pellets.
The crane in reality.