Modern locomotive construction by Meyer Jacob G. Arnold d. 1900

Author:Meyer, Jacob G. Arnold, d. 1900
Language: eng
Format: epub
Tags: Locomotives -- Design and construction
Publisher: New York, J. Wiley and Sons
Published: 1892-03-25T05:00:00+00:00

120 pounds. The area of a 19-inch piston is 283.53 square inches; the total maximum pressure on the piston will be equal to 283.53 x 120 = 34,023.6 pounds.

34023.6 ,, . = 0.3o4 square inch.

The nearest diameter corresponding to an area of 0.354 square inch is •$-£ inch. Therefore 1« + i = H inch, which is the diameter for the bolts through side-rod straps for the front and rear crank-pin. And }$ + I = IMJ inch, which is the diameter of the bolts through the side-rod strap for the central or main crank-pin.

RULE 65.—To find the diameters for the side-rod strap bolts in a consolidation engine: Divide the total maximum steam pressure on the piston by 128,000; the ijuotient will be the cross-sectional area in square inches of each bolt through the front and rear straps necessary to resist the shearing force. To the corresponding diameter, which we shall designate by the letter B, add § of an inch; the sum will be the required diameter of the bolts through the straps for the front and rear crank-pins. Again, to the diameter B, add £ inch; the sum will be the diameter of the bolts through the straps for the second and third crank-pins.

EXAMPLE 99.—Find the diameters for the side-rod bolts in a consolidation engine having cylinders 20 inches in diameter; maximum steam pressure per square inch of piston, 120 pounds.

The area of a 20-inch piston is equal to 314.16 square inches; the total maximum steam pressure on the piston will be equal to 314.16 x 120 = 37699.2 pounds.

37699.2

1^8000 " square inch.

The nearest diameter corresponding to an area of 0.294 square inch is § inch. Therefore f + f = 1 inch, which is the diameter of the bolts through the straps around the front and rear crank-pins. And £ + £ = l£ inches, which is the diameter of the bolts through the straps for the second and third crank-pins.

323. The bolts through the side-rod and also through the main-rod straps should be placed as close to the keys as possible, leaving only sufficient room to tighten the nuts. The distance rf, Fig. 449 or Fig. 451, that is, the distance from end of the wing of the strap to the first bolt, is generally made equal to about one and a half times the diameter of the bolt. The distance from center to center of bolts varies from 2 to 3 inches, depending on the diameters of the bolts; for engines with cylinders 16 inches in diameter and upwards, this distance is generally 3 inches, and for engines having cylinders 10 or 11 inches, it is •_' indies, and in some cases even less than that. Good practice seems to indicate that these bolts should be as close to each other as a sufficient clearance for the wrench will allow.

The side-rod bolts are generally tapered, the taper varying from ^ to £ of an inch in 12 inches. The diameters of the bolts found in the foregoing calculations are the small diameters.

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