Electrohydraulic needle bar positioning apparatus for tufting machines

In a tufting machine having a backing material support, means for feeding backing material longitudinally through the machine, a needle bar supporting a plurality of needles transversely of said machine, yarn supply means for feeding yarns to said needles, and means for reciprocating said needle bar to drive said needles into and out of the backing material upon the backing material support, a positioning apparatus for shifting transversely the needle positions relative to the backing material, comprising:

• (a) a reciprocably movable, hydraulically driven actuator,
• (b) coupling means connected to said actuator for changing the relative transverse positions of said needle bar and said backing material support in response to the relative position of said actuator,
• (c) pressurized hydraulic fluid supply means for said actuator,
• (d) valve means for controlling the flow of hydraulic fluid to said actuator,
• (e) electronic pattern control means having input means and output means,
• (f) said pattern control means comprising electronically programmed information corresponding to a stitch pattern predetermining the relative transverse positions of said needle bar and said backing material support for each longitudinal needle stitch position,
• (g) stitch sensor means communicating with said input means for producing an input signal for each needle stitch,
• (h) said pattern control means also comprising means for producing programmed electrical output signals commensurate with said programmed information at said output means,
• (i) said pattern control means further comprising electrical feedback means responsive to the actual position of said actuator producing corresponding feedback signals so that each of said output signals is conditioned by a corresponding feedback signal from said feedback means, and
• (j) electrical valve control means responsive to the programmed electrical output signals from said output means for actuating said valve means to cause said actuator to move to a position corresponding to the value of each of said output signals.