A rotational resistance apparatus and method of use is disclosed to
control movement of a carriage across a surface. The apparatus includes a
disc having an axial rotational axis, an axial first end portion, and
second end face portion that is substantially perpendicular to the axial
rotational axis. The first end portion rotationally engages a rotating
element of the carriage. Also included, is a cover having an axial
longitudinal axis, an axial outer end portion that removably engages a
frame of the carriage, and an axial inner face portion positioned
substantially perpendicular to the longitudinal axis. The longitudinal
and axial rotational axes are approximately co-axial and the inner face
portion and the second end face portion are in a selected rotational
frictional contact. Further included, is a first structure for selectable
axial urging of the cover toward the disc, being operational to further
selectably alter the selected rotational frictional contact.