Cloth spreading machine having improved cloth feed control and guide

In cloth spreading machine having drive means for moving the machine along a surface for spreading cloth along the surface and a cradle for holding a roll of cloth and feeding cloth from the roll for spreading along the surface in response to operation of cradle motor means:

• a) first tachometer means operatively connected to said machine drive means;
• b) second tachometer means operatively connected to said cradle motor means;
• c) first circuit means connected to said first and second tachometer means for providing a machine voltage signal proportional to the speed of said machine along the surface and a difference voltage signal proportional to the difference between the rate of feed of cloth from the roll and the speed of said machine along the surface;
• d) feedback circuit means having an output and having a summing node at the input thereof;
• e) second circuit means for applying said machine voltage signal and said difference voltage signal to said summing node;
• f) motor speed control means operatively connected to said cradle motor means and having an input connected to said output of said feedback circuit means;
• g) so that the speed of said cradle motor means is controlled to maintain the rate of feed of cloth from the roll substantially equal to the rate of travel of said machine along said surface;
• and
• h) a polarity reversing network connected between said first tachometer means and said first circuit means, said network being responsive to the voltage polarity output of said first tachometer means for providing a constant polarity voltage to said first circuit means regardless of the direction of movement of said machine along said surface.

In a cloth spreading machine having drive means for moving the machine along a surface for spreading cloth along the surface and a cradle for holding a roll of cloth and feeding cloth from the roll for spreading along the surface in response to operation of cradle motor means:

• a) speed control means connected in controlling relation to said cradle motor means and having an input;
• b) amplifier means having an output connected to the input of said speed control means and having an input;
• c) circuit means for applying a voltage signal to said amplifier input to cause said speed control to operate said cradle motor means at a given speed, said circuit means including resistance means for controlling the gain of said amplifier;
• d) electromechanical transducer means for converting movement of the cloth due to increased or decreased tension on the cloth during acceleration or deceleration, respectively, of the machine into addition or subtraction of resistance in parallel with said gain-controlling resistance to increase or decrease the gain of said amplifier to cause a compensating increase or decrease in the speed of said cradle motor means;
• e) said electromechanical transducer means comprising dancer bar means movably mounted on said machine and positioned to be moved in response to a change in tension applied to the cloth and electro-optical transducer means operatively associated with said dancer bar means for switching resistant in parallel with said gain determining resistance means in proportion to the degree of movement of said dancer bar means;
• and
• f) said transducer means comprising a cam rotatably mounted on said machine, means for converting movement of said dancer bar means into rotation Of said cam, and a plurality of electro-optical switches each comprising an LED and a phototransistor on opposite sides of a gap, said cam being positioned initially in all of the gaps of said switches, said cam being moved in response to increasing tension on the cloth to sequentially leave the gaps of said switches to sequentially add resistance in parallel with said gain controlling resistance to increase the speed of said cradle motor means.