This is my remake of 42108 because I don't like the chassis:
- outriggers are poor
- steering radius far too wide

Chassis has been constructed from 3axle variant (see other folder): 
Fourth axle is introduced as mirror of the rear one (3rd one is fix). It uses opposite but same steering angle. There is a 12:20 tranmission for the front axle. The resulting diametre of turning cycle is 56 cm (22", outer diameter). 
Steering can be done from rear (upper knobwheel) and from warning lights.
Driver cabin has been adapted from the 42108 set.

All four outriggers are controlled from one point (lower knob wheel on rear) thus turning simultaneously. In contrast to 3 axle version I had to provide original input to all four outriggers and use worm gear transmission on all of them due to the weight of the crane.

Superstructure has been taken from 42108 in a modified manner: 
a) boom lenght
   This has been reduced by a 3x11 panel to match the shortened chassis.
b) machine cabinet
   The original configuration appeared to be to wide (with respect to the chassis length). 
   By small changes it was possible to reduce width by two 'studs'. Note that the yellow top panels at the counterweight to not fit properly.
   Boom elevation has now 12:20:12:12 gear train
   Winch has now 20:12 transmission.
c) I removed the friction elements from winch and boom extension. I also replaced the knob wheels by cranks.

list@electronic-origins.net, 02/2020