(299) This step having been accomplished, the next operation is to engage the backing-off friction. As shown in Fig. 158, the boss of the wheel =A^{ 1}= is formed with a ring groove, into which a claw fastened on a short stud fits. The lever =D= is also fixed on the same stud, so that any movement given to it is communicated to the claw and backing-off friction. The lower end of the lever is forked and passes over a rod =X= extending along the side of the headstock. This rod is guided by a bracket fixed to the side of the frame, and has the two stop hoops =X^{ 1} X^{ 2}= fastened on it. Between the stop hoops a spiral spring, always in compression, is threaded upon the shaft, one end pressing against the lever =D=, and the other against the hoop =X^{ 2}=. It will be readily understood that the compression of the spring will tend to push the lever =D= in the direction of the arrow, until its motion is stopped by a link connected with the slide in the arm, to which is fastened the lever =H=. It is essential that the engagement of the backing-off clutch should be practically simultaneous with the transferring of the strap from the fast to the loose pulley, and it is therefore desirable that the spring on =X= should be put in compression a little before the actual traverse of the strap.
(300) This is accomplished by means of the swinging lever =V= shown in Fig. 162. This is hinged upon the square, and is formed, as shown, with an open mouth, at the upper part of which is an angular projection or lip. Pivoted on the framing is the lever =L=, the horizontal arm of which carries a small runner, which engages with the incline of =V= as the carriage runs out. The lever =V= cannot, until the termination of the stretch, be swung upon its pivot by reason of its connection with the faller locking lever =A=. When, therefore, the bowl in the lever =L= engages with the incline of =V=, the lever =L= is oscillated, so that the spring on =X= is further compressed. The spring is, therefore, in a position to push the backing-off lever forward, as soon as the latter is freed. The engagement of the lever =L= with the lever =V= takes place a few inches before the carriage arrives at the end of its outward run.