The traveler number identifies its weight. The ideal weight controls the yarn balloon, makes a firm package with good weight and allows good traveler life. If too light, balloon may be excessive, causing fuzzy yarn and ends-down toward the bottom of the bobbin. Travelers which are too heavy cause excessive ends-down at the top of the bobbin. Greater traveler friction against the ring from heavy travelers generates heat that may damage fibers, burn travelers and cause excessive ring wear. Correct traveler weight can be determined only after practical trials on a specific application. The factors which influence the correct choice of traveler number are:

• friction between traveler and ring
• ring conditions
• lubrication (cotton has a natural lubricant - synthetic fibers have additives)
• spindle speed
• air conditioning and relative humidity
• yarn twist
• fiber quality

The choice is based on the number of yarn breaks during all phases of filling the bobbin, as recorded during past experience or through testing. Usually, the pattern of yarn breaks are similar to the relation between the curves in the following Figure (1).

Choose the weight of traveler which will minimize variations in yarn breaks during all the phases of filling up the bobbin. Very light travelers can, in certain situations, cause breaks due to the oversize balloon. Such a balloon can allow the yarn to touch the separators, causing a very hairy yarn. Also, light travelers produce soft packages, which waste labor.

On the other hand, travelers which are too heavy for certain applications can cause yarn breaks in the upper part of the bobbin.

The friction of the traveler against the ring is greater when the travelers are heavier, creating heat which can damage the fibers, burn the traveler and wear out the ring. To make the choice, use practical experience or determine the correct weight through physical tests.

The number relating to the depth and diameter of the traveler. The circle is involved in matching the traveler to spinning variables affecting the traveler balance, and the yarn clearance. Only one of the many possible circles is just right for a specific use.

When the circle is larger than it should be, travelers run off-balance, causing excessive friction and resulting increase in the percentage of ends down. More serious and costly in the long run is the grooving of the outside of the ring web, which reduces efficiency and causes early ring replacement.

The time-tested principle for circle selection is - the circle should be no larger than necessary to fit the ring flange and provide clearance for the yarn. To put it another way, the circle should be as small as possible, consistent with clear running . . . and that's where all the variables cloud the issue.