A device for adjusting a nominal value of the dimension of an actuator, the longitudinal dimension of which can be changed by applying an external electromagnetic or electrostatic field, the magnitude of the external electromagnetic or electrostatic field being associated with the longitudinal dimension of the actuator, or soft-magnetic and highly magnetoelastic layer being connected to the actuator in such a manner that a change in length of the actuator produces a change in the mechanical stress in the layer. The change in mechanical stress in the layer produces a change in the value of an inductance, the mechanical stress in the layer being inferred from the magnitude of the inductance in sensor electronics and the longitudinal dimension of the actuator being inferred from the mechanical stress in the layer. The longitudinal dimension of the actuator is compared with a predetermined nominal value in a comparison device and a correcting variable is output by a control device when a difference between the longitudinal dimension of the actuator and the predetermined nominal value is detected by the comparison device. The correcting variable is predetermined in such a manner that the detected difference disappears.

A piezoelectric needle selector utilizes an upstanding knitting cylinder having a multiplicity of needle jacks mounted thereto for independent movement in a direction parallel to the axis of the knitting cylinder. A plurality of piezoelectric actuators, each having a stack of planar piezoelectric elements coupled at one end to a plunger, are mounted via respective holders to a fixed support frame disposed adjacent the knitting cylinder. The selective application of voltage pulses to the piezoelectric actuators results in the linear travel of the associated plungers toward and away from the knitting cylinder. The linear travel of the selected plungers is translated into the movement of the desired needle jacks up and down on the knitting cylinder, as by several needle select levers pivoted by the plungers and acting on the usual butts on the needle jacks.

A mechanism selects and controls the raising and lowering of needles in circular and flat bed knitting machines having a plurality of adjacent needles. A rocking pusher is provided for each needle to move each needle back and forth between an outwardly projecting active position and an inward inactive position. Each rocking pusher is engaged with a corresponding cam when the needle is in the engaged position, and is disengaged from the cam in the inactive position. A deflector corresponds to each rocking pusher, and is engageable with a cam profile, which determines the movement of the deflector for its engagement with the rocking pusher. This moves the rocking pusher from the active position to the inactive position. A controllable retaining member engages the deflector to cause the engagement of the deflector with the cam profile. The retaining member is controlled by a control program member, which is controlled by a control program.

Electrically actuated jack selectors for a knitting machine which are normally positioned out of engagement with the needle jacks or pattern jacks of the knitting machine. When each of the jack selectors is actuated, either by a perforated tape loop or by a drum, the jack selector is deflected into a position along the path of an associated needle jack or pattern jack and, upon engagement therewith, displaces the associated jack relative to the cylinder so that, depending upon the direction of deflection of the jack selector, either the needle jack or the pattern jack will not be raised by the cylinder cam. Each jack selector includes a knife edge cam portion that is engaged by a conically shaped tip on the movable armature of a solenoid that is associated therewith. A comb-like element may be used to initially position a group of the jack selectors in order to predetermine the direction of deflection thereof. The teeth of the comb-like element, between which the jack selectors are positioned, also limit the angular deflection of the jack selectors.