Occasional Electronic Publication No. 1 - Society for Industrial ...

Pratt Family of Trusses with
Multi-intersecting Diagonals
Pratt-type configurations where tension diagonals cross two or more verticals.
Whipple's double-intersecting truss, an extensively used configuration, was never patented.
This drawing is from Whipple's A Work on Bridge Building, 1847.
PATENT CHRONOLOGY
Lowthorp 1857: Segmented upper chord. Vertical post connection designed to permit “vibrations.”
Murphy 1861: Detail for the use of eye-bars and pins.
Linville 1862: Connection detail for double-intersecting trusses.
Kendall 1862: Alternating tension and compression verticals. Additional chord at mid-height. Lattice effect.
Murphy-Whipple 1863: Not patented. Double-intersecting Pratt configuration. Wrought iron used for
tension members and cast iron for compression members. Pin-connected joints.
Whipple-Murphy 1863: Alternate name for Murphy-Whipple.
Linville & Piper 1865: Detail for improving double-intersecting truss connections.
Smith, F. H. 1869: Patent is for a joint detail. A double-intersecting truss configuration is shown to
demonstrate the application of the detail.
Herthel 1870: Double-intersecting diagonals pass through verticals. No counters. Vertical end posts.
Smith, F.H. 1872: Double-intersecting diagonals. Verticals and end posts are inclined; their center lines
converge to a point high above the centerline of the span.
Whipple 1872: Patent for a vertical-lift drawbridge features his unpatented double-intersecting truss configuration.
Clark, Bonzano & Griffen 1873: Diagonals intersect four panels.
Hammond, Morse, & Abbott 1876: Pratt single-diagonal configuration with double-intersecting counterdiagonals.
Davies 1877: Double-intersecting tension diagonals. Double end posts. Double compression diagonal in end
panels.
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