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Tri-Sector was a simple construction system, using left and right hand triangular flanged triangular plates. It was made in the UK in circa 1921.

Manufacturer / Distributor

The Hobran Engineering Co. Ltd., Shelsley Works, Wolverhampton, UK

Info from the Metal Constructional Systems Database for TRI-SECTOR

System Type
Non-Meccano type
United Kingdom
Boss Type
Boss Thread
Diametrical Pitch of Gears
No. of Parts in System
10 (some significant doubt)
Hole Pitch (Spacing) (mm)
31.8 (see comment *1)
Diameter of holes in Strips(mm)
4.7 (see comment *2)
Diameter of the Bore in Bosses(mm)
Diameter of Axle Rods(mm)
Types of Nuts and Bolts
Material/Finish of Nuts and Bolts
Size of the Nuts across Flats (mm)
Bolt diameter (mm)

The only structural parts are right hand & left hand Flanged Triangles, 2½x3¾". Known from 1921 ads. May have been short lived. *1 1¼". *2 In the Flanged Triangles.

The MCS document for this system is shown below. It can also be downloaded to your computer if desired here

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The report can be zoomed into, made full screen or downloaded as a pdf document by using the controls provided

There are currently no manuals, leaflets or photos etc. available for downloading. If you can supply any, please get in contact with me.