(251) Referring now to Figs. 140 and 141 it will be noticed that there are two cradles =A= and =B=, centred respectively on the pins =A^{ 1}= and =B^{ 1}=. Fixed in the upper cradle =A= are hooks, one at each side, which are connected, as shown, with double hooks =C D=, passing through ears on the lower cradle =B=, having weights attached to their lower ends. The lower cradle =B= has fixed in it a pin =E^{ 1}=, engaging with a slot in the lever =E=. =E= is centred on the pin =F=, and is coupled at its lower end to the rod =R=, which is connected with the double bevel wheel =T T=, this connection being shown in Fig. 134. Two catches =G G^{ 1}=, centred at their lower ends to the frame carrying the cradles, are coupled by the helical spring =H=. It will be noticed that the pawls of the catch levers are differently shaped, so as to engage with the teeth of the rack or ratchet wheel =I= on the upper and lower side of the centre respectively. The rack wheel is fixed on the same centre as the cradle =A=, as is also a bevel pinion =J=, gearing with a similar one =J^{ 1}= fixed on the upright shaft =K=, Fig. 141. At a higher point on =K= a spur pinion =P^{ 1}= is fastened, which gears with the teeth on the rack =P=, controlling the strap guides. Two levers =L L^{ 1}= are pivoted to the frame as shown, and are coupled at their inner ends by a helical spring =M=, which is carried round the centre =B^{ 1}=. The inner ends of =L L^{ 1}= engage with shoulders or corners =N N^{ 1}=, formed in the lower cradle =B=. Fixed to the bobbin rail is the double slide =Q=, which has a pin =O= sliding in it, on which the end of the connecting rod =S= is centred. This rod passes through bearings placed in the cradle =A= (see Fig. 140), and is formed with a toothed rack at its lower side with which a wheel =T= fixed on the pin =A^{ 1}= gears. These are the whole of the parts of this particular mechanism, but a reference to Fig. 134 will show that the rack =P= has a weight attached to it by a chain, which is always tending to draw it inwards, and move the strap. In addition to this it causes a torsional strain to be exercised on the shaft =K=, and consequently on the rack wheel, which causes the latter, when released by the catches, to rotate.