Patent ID: 7037228

Claim:
A chain tension-imparting device comprising: a plunger, which retractably protrudes toward a traveling chain; a housing body which includes a plunger sliding hole into which said plunger is retractably fit-inserted; a protrusion biasing spring, which biases said plunger in a protrusive direction with respect to said housing body; a cam-receiving ring, fitted on the plunger from the outside in a diameter-increased concave portion of said plunger sliding hole on its opening front end side and which is displaced in the axial direction of the plunger; a cam-receiving ring biasing spring for biasing said cam-receiving ring in the protrusive direction of the plunger; a plurality of wedge-shaped cam chips, which slide on a sloped cam guide groove formed on said cam-receiving ring and engage with a plurality of racks engraved on the outer circumference of said plunger respectively; a cam-guiding ring, fitted on the plunger from the outside in a diameter-increased concave portion of said plunger sliding hole at its opening front end for guide controlling disengagement of the plurality of wedge-shaped cam chips; and a seal plate, which retractably fit-inserts said plunger and movably seals said cam-receiving ring biasing spring, said cam-receiving ring, said wedge-shaped cam chips and said cam-guiding ring sequentially disposed in a diameter-increased concave portion of said plunger sliding hole on its opening front end side, wherein when said cam-guiding ring is brought into contact with the back of said seal plate in the diameter-increased concave portion of said plunger sliding hole on its opening front end side, said cam-guiding ring guide-controls the disengagement of said wedge-shaped cam chips.