Fig. 172.J.N.
(351) The back shaft is also engaged and detached in a different manner. It is driven from the roller shaft by a train of wheels, but the last of the train is a compound one, consisting of a large wheel with a smaller pinion. The latter gears with the back shaft wheel, and is put into or out of gear accordingly, as it is desired to revolve or stop the rotation of the back shaft. For this purpose the compound wheel is borne on a hinged lever, called commonly the Mendoza lever, which is weighted in a suitable manner. The exact origin of the word Mendoza, as applied to this lever, is difficult to define, but it probably arises from the French phrase, main douce—Anglicè, the soft hand. However this may be, the function of the lever is to put the pinion into and out of gear with the backing-off wheel, and to effect this, its motion is controlled by a cam or eccentric on the cam shaft. This cam works in a fork in a lever, and the rotation of the cam shaft raises or lowers the Mendoza. The object of the weight is to ensure the full engagement of the pinion and back shaft wheel, so as to obviate any jumping out of gear at the commencement of winding. There is some tendency towards this unsteadiness of driving in the early part of the outward run, and it is desirable to lock the Mendoza lever in position.
Figs. 174 and 175.J.N.
Fig. 176.
(352) Messrs. John Hetherington and Sons employ a special device by which this difficulty is overcome. The mule, as made by them—arranged to be driven with the rim shaft transversely, instead of longitudinally, placed in the headstock—is illustrated in Fig. [176] in longitudinal elevation, and in Fig. [177] in back view. Both views show the method of driving quite clearly. On the outward end of the Mendoza weight a pin is fixed which takes into a fork formed at the upper end of a vertical lever. The fork is shaped with a shoulder or recess, below which the pin referred to can slip when desired to lock the Mendoza in position. A small ear is formed on the vertical lever, through which a set screw is passed, the point of which comes in contact with the end of a horizontal lever centred on a pin fixed in the headstock. The last named lever has a long tail extending outwards toward the carriage. When the carriage comes up to the back stops and the Mendoza lever falls, putting the driving pinion into gear with the back shaft wheel, the long tail of the horizontal lever is raised, and the effect is that the pin in the Mendoza weight passes under the shoulder of the fork in the vertical catch lever, and so firmly holds the Mendoza lever down. As the latter carries the driving wheel, the pinion is kept firmly in gear, and the effective driving of the carriage is obtained. As soon as the carriage has run out a little—by which time it has gained momentum—the horizontal lever is released, and its long end falls, thus freeing the catch or pin in the Mendoza. Sometimes the minder, in cleaning, runs out the carriage a little and then changes the cam, without freeing the horizontal or locking lever. If afterwards the mule is started the carriage endeavours to run in, although the back shaft wheel and its driving pinion are in gear. This leads to breakages, and in order to avoid these, Messrs. Hetherington have arranged a small relieving lever, coupled to the long lever, so that any motion of the latter causes the relieving lever to act and free the Mendoza catch pin, without reference to the position of the horizontal locking lever. This mule is arranged with the extra band for driving the taking-in side shaft D referred to in paragraph 286. The band E is driven from the counter shaft R, and passes round a double grooved pulley on D. It is kept in tension by the pulley F, carried by a frame which can be moved inwards by the quadrant rack G with which a worm gears. The remaining reference letters indicate the same parts as in the other illustrations.
