Four parts manhole enabling an easy install and height adjustment

Abstract

A manhole comprised of four parts is provided. The manhole is comprised of an outer-manhole pipe, an inner-manhole pipe, a manhole cover, and a support pipe. Pluralities of concave arc band shape blades are horizontally developed along the inner surface of the outer manhole pipe. Same number of convex arc band shape blades is horizontally developed along the outer surface of the inner manhole pipe. The inner-manhole pipe is inserted into the outer-manhole pipe vertically when the two kinds of arc shape blades aligned to make pass way for each other. When a desired height is reached, workers rotate the inner-manhole pipe 60 degrees horizontally and put down the inner-manhole pipe. Then the two kinds of blades are overlapped and fix the height of the manhole cover. A support pipe, comprised of two pieces of equal hemi-pipe connected one end, is engaged between the top flange of the inner-manhole pipe and top end of the outer manhole pipe to hold and support the distance between them.

1 . A height adjustable manhole comprised of; 
 a manhole cover with handle cam lock that is comprised of a handle, a cam, a cam shaft, and a cam lock box; and    an outer-manhole pipe equipped with pluralities of concave arc band shape blades of same size, whose outer diameter is equal to the inner diameter of the outer pipe and inner diameter is 1 mm larger than the outer diameter of the inner pipe and center of each piece of the concave arc band shape blade locates 60 degrees apart from the neighboring concave arc band shape blade's center and a groove to guide a protrusion of a convex arc band shape blade is developed along the upper surface of each concave arc band shape blade and a dimple of the similar size of the protrusion is developed at the center of the groove to hold the position of the protrusion when the arc shape blades of an inner-manhole pipe and outer manhole pipe are overlapped and a flange with pluralities of flange holes is developed at the middle of outside thereof; and    an inner-manhole pipe equipped with a flange that has an opening to receive the cam shaft and pluralities of convex arc band shape blades of same size, whose inner diameter is equal to the outer diameter of the inner-manhole pipe and outer diameter of the annular plate is 1 mm smaller than the inner diameter of the outer-manhole pipe and center of each piece of the convex arc band shape blade locates 60 degrees apart from the neighboring blade's center and a small protrusion is developed at the center of the lower surface of each convex arc band shape blades; and    a support pipe that is comprised of two equal hemi-pipes, one end of each hemi-pipe is connected by two male connectors and two female connectors developed on each other hemi-pipe and the other ends of the hemi-pipes are connected by a key and a key hole and is installed between the top of the outer-manhole pipe and the bottom of the flange of the inner-manhole pipe.    
   
   
       2 . A height adjustable manhole of  claim 1 , wherein three pieces of convex arc band shape blades of same size are horizontally located along the outer surface of the inner manhole pipe in one layer and three pieces of concave arc band shape blades are horizontally located along the inner surface of the outer manhole pipe in one layer.  
   
   
       3 . A height adjustable manhole of  claim 1 , wherein the inner-manhole pipe move vertically freely when a space between the two neighboring convex arc shape blade is occupied by a concave arc shape blade,