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A hinge on a ladder comprises outer casing pair, inner casing pair, a fixing plate with a shaft and three lock pins, a central rivet pin, and a button knob. The outer casing pair and the inner casing pair are pivotally engaged to each other in such a way that the circular plate portions on the casin

A hinge on a ladder comprises outer casing pair, inner casing pair, a fixing plate with a shaft and three lock pins, a central rivet pin, and a button knob. The outer casing pair and the inner casing pair are pivotally engaged to each other in such a way that the circular plate portions on the casing pairs facially contact with one another. When the locating holes on the outer casing pair align with three specific ones of nine locating holes on the inner casing pair, the three lock pins are pushed toward the outer casing pair and to pass through the aligned locating holes and perform a locking position. When the button knob is pressed toward the outer casing pair against the restoring force of the spring, the three lock pins move away the locating holes. Therefore, the elongated projection ends of the three lock pins fit with the elongated slots on a half piece of outer casing pair to perform an unlocked position.

대표청구항 ▼

1. A hinge on a ladder, comprising:outer casing pair, said outer casing pair further comprising a first and a second outer casing halves fixedly attached to each other oppositely, the outer casing halves having an upper circular plate portion and a lower rectangular plate portion, the respective upp

1. A hinge on a ladder, comprising:outer casing pair, said outer casing pair further comprising a first and a second outer casing halves fixedly attached to each other oppositely, the outer casing halves having an upper circular plate portion and a lower rectangular plate portion, the respective upper circular plate portion being radially disposed with three specified locating holes, the locating holes on the first outer casing half aligning with the locating holes on the second outer casing half, each of the locating holes on the first outer casing half extending an elongated slot laterally, and a gap being between the upper circular plate portions of the outer casing halves; inner casing pair, said inner casing pair further comprising a first and a second inner casing halves fixedly attached to each other oppositely, said inner casing halves having an upper circular plate portion and a lower rectangular plate portion respectively, the upper circular plate portions facially contacting with each other, being received in said gap on the outer casing halves and providing nine spacing apart locating holes radially, and the locating holes on the first inner casing half aligning with the same on the second inner casing half; a central pin rivet, having an axial through hole therein, passing through and fixing to all the upper circular plate portions such that the outer casing pair and the inner casing pair can be pivotally moved relatively; a shaft with two ends, passing through the axial through hole in the central pin rivet with one of the ends thereof; a fixing plate, having a center part being fixedly attached by the other end of the shaft; three lock pins, being disposed on the fixing plate spacing apart to each other and aligning with the locating holes on the outer casing pair, each of the lock pins having two ends, one of the ends fixed to the fixing plate and the other one of the ends being an elongated projection; a button knob, being a shape of disk, having a central inner bore to be fixed to the other one of the ends on the shaft; and a spring with two hook ends, being disposed between the button knob and the second outer casing half, and said two hook ends engaging with the button knob and the second outer casing half respectively; Whereby, while the outer casing pair and the inner casing pair are pivotally moved relatively and the locating holes on the outer casing pair align with three specific ones of the locating holes on the inner casing pair, the fixing plate with the three lock pins and the shaft is pressed toward the first outer casing half and the three lock pins pass through the aligned locating holes to perform a locking position; and while the button knob is pushed toward the second outer casing half against the restoring force of the spring, the three lock pins move away the locating holes and the elongated projection ends of the three lock pins fit with the elongated slots on the outer casing half to perform an unlocked position.