One of three suspension spring assemblies. The platter and tone-arm "ride" on the sub plate carried by the springs. The motor and controls are mounted to the top plate. This isolates motor vibration from the platter/tonearm. Note the upper and lower rubber washers and the foam insert. The foam insert fits tightly around the stud and inside the spring serving to dampen and affect spring rate.
For info on my efforts to correctly set up the suspension on this table, please see the Thorens Tweaks page.