Handbook of Railroad Construction; For the use of American engineers. / Containing the necessary rules, tables, and formulæ for the location, construction, equipment, and management of railroads, as built in the United States.

by George L. Vose

requiring a rod of three fourths inch diameter.

The posts in this structure, correspond to the braces in the Howe bridge; only being vertical, they need not be so large.

182. The following table gives all the dimensions necessary for proportioning this truss.

Span.	Rise.	Chords.	End post.	C post.	End rod.	C rod.	Counter rod.
50	10	2—8 × 10	5 × 5	42	2—1⅜	2—1	1—1½
75	12	2—8 × 10	6 × 6	52	2—1⅝	2—1	1—1½
100	15	3—8 × 10	7 × 7	62	2—1¾	2—1	2—1⅛
125	18	3—8 × 10	8 × 8	62	3—1⅞	3—1	2—1⅜
150	21	4—8 × 12	9 × 9	62	3—2⅛	3—1	3—1⅛
200	24	4—8 × 16	10 × 10	62	5—1⅞	5—1	3—1⅛

And the following, the sizes of counter rods, for different panels.

Length of panel.	Height of panel.	Approximate diagonal of panel.	Diameter of the rod.
			One in a set.	Two per set.	Three per set.
10	12	16	1⅝	1⅛	⅞
11	13	17	1⅝	1¼	1⅛
12	14	18	1¾	1¼	1⅛
13	15	20	1¾	1¼	1⅛
14	16	21	1⅞	1⅜	1⅛
15	18	23	1⅞	1⅜	1⅛
16	21	26	2	1⅜	1⅛
18	25	27	2	1⅜	1⅛

The advantage possessed by this bridge, over Howe’s plan, is that the panel diagonals may be adjusted by the screws; by which control is had over the form of the truss, and of the duty done by the several parts. Change of form cannot be had by working upon verticals. Howe’s bridge must be adjusted by wedging the braces and the counter braces.

183. The manner of drawing the bevel block in this bridge, is shown in fig. 68 b. The proportions of the block depend upon the proportions of the panel; and the dimensions, upon the size of washer used.

Let C C be the centre line of the post, and A B the chord. Let o m, and o n, be the panel diagonals, and H and y, the length of the washers.