PURPOSE: To automatically control the falling height, etc. of a ram by a method in which a bar having large numbers of detection holes is provided between ends of rods along both rod cylinders, and the holes are detected by a photoelectric switch to detect the action and position of the rods.
CONSTITUTION: A bar 10 is provided between rods 1 and 2 by fixing its end along sides of both rod cylinder 3. The bar 10 has a long hole 13a corresponding to the reference position β of a ram 4 during the stoppage of operation, and the upper end of the hole 13a is designed to meet the reference when the rod 2 goes down to the lowest. Also, a hole 13b of a length α and many small holes 13cW13c" and 13dW13d" are provided in the other side of the bar 10. The action and position relation of the rods 1 and 2 during the operation of an oil-pressure hammer is obtained from the presence and absence of holes, detected by photoelectric switches 14W14" provided in the cylinder 3. By an automatic control circuit, control is made automatically on the falling height of the ram and abrasion of a cushion material 6 is automatically detected.
YOSHIDA KAZUYUKI
MIZUNO TOSHIYUKI
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