It is a pole or logging truck with a walking beam. The trailer could be shifted to any length away from the tractor using the beam.
The picture is from the AWM and shows a similar unit being used as a logging jinker in the Northern Territory, Australia 1943 by the AIF.
Cheers
Cliff
__________________
Cheers
Cliff Hutchings
aka MrRoo S.I.R.
"and on the 8th day he made trucks so that man, made on the 7th day, had shelter when woman threw him out for the night"
MrRoo says "TRUCKS ROOLE"
