350 Tetsu (Reru) waku [Steel (Rail) Frames Used at the End of the Meiji Eras]

Main Text at the Bottom Middle
These steel (rail) frames were used at the end of the Meiji, Taisho, and Showa eras. They were used at the Central Coal Pit of the Futase Branch of the Imperial Steel Works, which was opened in 1910 according to the enterprise’s 50-year plan. I do not know if they were used at other large-scale coal pits. Most rails used at this pit were 60 pounds per yard. 75 or 100-pounds-per-yard rails were also used for frames supporting the roofs of machine stations. Frames using straight rails were composed of three parts of a beam and two pillars, and all frames used in levels had timber pillars. The arched frames supporting the 1,000-meter-long main slope of Inatsuki Coal Pit were completed in the beginning of the Showa era. These frames were a little more than 2 meters and 3 meters in height and width respectively.

Descriptions of Each Frame
Arched Frame at the Top Right
Tough fish plates and bolts were used on joints of arched frames for winding machine stations or pump stations.
The rails for arched frames used at Mitsui Yamano Urushio Coal Pit were curved with heads facing outwards contrary to those used at other pits.

Arched Frame at the Bottom Right
This kind of arched frame was used in main slopes etc. The number of holes in the fishplate connecting the two arches was reduced to only two.

Frame at the Top Left
Both ends of the head of the straight rail turned upside down were inserted into the cavities cut on the tops of pillars. Building this frame required complicated work from underground carpenters. Additionally, they had to wind wires around the jaws of the pillars. Therefore, frames of this type were rarely used.

Frame at the Middle Left
Knuckles were caulked with rivets onto the bottom of the beam (rail) at the points about 1.5 centimeters apart from its ends in order to fix it on the tops of the pillars with them.

Frame at the Bottom Left
The crossbeam of the main support unit (kagume-waku) of this compound frame was composed of two paralleled rails. These rails were once holed and combined with bolts, but the holes often caused them to break. Therefore, the method was improved and the rails were combined with flat irons by shrink fitting.