important operation of "backing off"
commences.

It maybe at once explained that "backing off" means the reversing of the
spindles; the uncoiling of a portion of the yarn from the spindles; and
generally putting all the requisite apparatus into position ready for
winding or coiling the attenuated and twisted rovings upon the spindles.

Here come now into action those most beautiful and ingenious
applications of mechanical principles, the working out of which entailed
so many years of arduous effort, and which rendered the mule practically
self-acting and automatic.

By a most wonderful, intricate and clever combination of levers, wheels,
pulleys and springs, aided by what is called a "friction clutch," the
instant the spindles have ceased twisting the yarn, they are reversed in
direction of revolution.

This reversal only occupies two or three seconds, and as the motion
imparted to the spindles is very slow at this stage, the practical
effect is, that a small portion of yarn is "_uncoiled_" from each
spindle, sufficient to allow of two "guide wires" to assume proper and
necessary positions for winding the attenuated threads upon the
spindles.

These two wires are termed "faller wires," and while one is controlled
by the cop-shaping mechanism and termed the "winding faller wire" the
other simply keeps the threads in the requisite state of tension during
"winding on" and is termed the "counter" or "tension faller wire." Both
these wires can be seen in Fig. 28. During backing off, the "winding
faller wire" has a descending motion, while the "counter faller" has an
ascending motion, these being necessary for them to attain their proper
positions for "winding on."

Image: FIG. 28.--Mule showing action of faller wires.

The movement of these faller wires into proper position, and the
uncoiling of a small portion of yarn from each spindle, are both brought
about by the "backing off" motion, which formed an important part of
Roberts' Mule. It may be remarked, however, that certain of the
predecessors of Roberts had made great efforts in this direction, thus
making the way much easier for his applications, which were entirely
successful. When "backing off" is completed, all the necessary parts are
in position for winding the 64 inches of thread just given out upon each
spindle.

This practically involves three primary and most important operations.
(1) The drawing-in of the carriage back to its original position. (2)