{HEAD ~ The friction resistance force} adds to {TAIL ~ the torsional resistance force} of the spring during application of the pedal and subtracts from the torsional resistance force of the spring upon release of the pedal, whereby to create a hysteresis effect 
adds to
{ HEAD ~ The friction resistance force } adds to { TAIL ~ the torsional resistance force } of the spring during application of the pedal and subtracts from the torsional resistance force of the spring upon release of the pedal , whereby to create a hysteresis effect
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH