natural resonant frequency of the guide wheel and spring combination this oscillation may result in significant fluctuations in the force supporting the guide link 403 as well as intermittent contact between the guide link 403 and the guide wheel 409 this in turn results in excessive noise increased wear and decreased efficiency and power output 0037 fig5 is a perspective view of a guide link and guide wheel assembly in accordance with an embodiment of the invention in fig5 a guide link 500 is supported at its free end by a fixed guide wheel 501 and a spring loaded guide wheel assembly 502 the guide wheel assembly 502 includes two springs 504 505 and a guide wheel 506 springs 504 and 505 force the guide wheel 506 against the guide link 500 springs 504 and 505 have the combined force necessary to hold the guide wheel assembly 502 in contact with guide link 500 in addition spring 504 and spring 505 each have a different natural frequency of oscillation i e each has a different spring rate by selecting springs with non overlapping natural frequencies at least one spring will advantageously not be in resonance at all times during operation as mentioned above the guide wheel assembly 502 will typically.