A variable spring resistance to movement of a rod uses a plurality of
springs permanently connected between a base and a stack of end connector
links extending in the direction of the rod movement. Selecting which of
the links is connected to the rod then determines which of the springs
are deployed to resist movement of the rod, without requiring any
disconnection or reconnection of the springs. The selection can be made
by a pin inserted through an aligned hole between a link and the rod. The
arrangement can also be inverted with the springs connected between the
links and a moving element, and the rod or other link selector being
fixed to a base. Connecting one of the links to the rod then determines
which of the springs will be extended between fixed and movable elements
to establish a selectively variable spring resistance.