Leveling device of road paving machine

Abstract

[Problem] To improve performance by making it possible to properly conduct minus crown paving work in a paving work width region in which paving work in a minus crown has been impossible in a leveling device which is provided with a main screed and a pair of extendable screeds having almost the same width as the width of the main screed and is of any type among a type in which the pair of extendable screeds is disposed behind the main screed, a type in which the pair of extendable screeds is disposed in front of the main screed, and a type in which one and the other of the pair of the extendable screeds are disposed, respectively, in front of and behind the main screed. [Solution] A pulling mechanism which, if the crown amount is set to a minus amount when the respective inner ends ( 21 a, 22 a ) of a pair of extendable screeds ( 21, 22 ) are extended in a range not going beyond a machine center line, pulls up screed plates ( 21 b, 22 b ) in a required length range on the sides of the respective inner ends (21 a, 22 a ) of the pair of extendable screeds ( 21, 22 ) according to the minus set amount of the crown amount.

What is claimed is: 
     
         1 . A leveling device of a road paving machine which is provided with a main screed and a pair of extendable screeds having a width approximately equal to a width of the main screed and extending and retreating in directions opposite to each other, the leveling device of a road paving machine being of either one type of a type where the pair of extendable screeds are disposed behind the main screed, a type where the pair of expendable screeds are disposed in front of the main screed, or a type where one and the other of the pair of extendable screeds are disposed in front of and behind the main screed in a divisional fashion, wherein the leveling device of a road paving machine is provided with a raising mechanism which, when a crown amount is set to minus in a case where respective inner ends of the pair of extendable screeds have been extended in a range where the respective inner ends do not exceed a machine center line, raises screed plates in required length ranges on the sides of the respective inner ends of the pair of extendable screeds according to a minus set amount of the crown amount. 
     
     
         2 . The leveling device of a road paving machine according to  claim 1 , wherein the raising mechanism is configured as a refraction up-and-down type where the respective screed plates in required length ranges are raised in an angled fashion by utilizing lower face portions of the respective extendable screeds at required length regions of the pair of extendable screeds from the respective inner ends as hinge portions. 
     
     
         3 . The leveling device of a road paving machine according to  claim 1 , wherein the raising mechanism is configured as a parallel up-and-down type where the respective screed plates in required length ranges are configured so as to be slidable vertically at required length regions of the pair of extendable screeds from the respective inner ends, and the respective screed plates in required length ranges are raised while being slid in parallel with slide faces.