MIL-HDBK-1005/6

reduction. Normally the float capability of a crane is such that a curve of

300 feet radius can be traversed with a safety factor greater than two and

without a gage reduction.

Minimum Radius. It is desirable that the radius of the central

3.4.2

portion of the curve be not less than 80 feet, except where extreme space

limitations force this condition.

Float for New Cranes. Prior to purchase of new cranes, the

3.4.3

existing track system is to be investigated to determine the gage to which the

crane must be built and the amount of lateral float required in the crane.

Transferring from One Track System to Another. When cranes are

3.4.4

transferred from one track system to another, float requirements must be

determined and the running gear reconstructed as required to fit the new track

system.

Transition Curve (Inside or Control Curve). This transition curve

3.5

is a series of compounding circular arcs, in which change of degree of curve

is uniform and directly proportional to the flexible curve length. The first

20 feet of curvature of all transition curves is identical.

Gage Reduction. Although the actual reduction for a given radius

3.5.1

may be computed precisely, the gradual reduction between tangent gage and

reduced gage is an approximation.

Switch Curve (Inside or Control Curve). The first 20 feet of the

3.6

transition curve, which is the switch curve, is an arc of constant radius of

300 feet. All switch curves, being identical, permit the standard switch to

be inserted at the point of tangency of any curve design in accordance with

these criteria, at any time (See Figure 7).

Switch Alignment. Although the body of the switch may project a

3.6.1

few inches beyond the sharp edge of the switch curve, the switch alignment

will match precisely any designed flexible transition. Switching from curved

track shall not be used unless the radius of the curve is greater than 300

feet and the turnout is to the outside of the curve, that is, not the center

of the curve.

Main Circular Curve (Inner). This curve is an arc of constant

3.7

radius located between the beginning and ending transition curves (See Figure

7).

General Requirement. The general practice is to make an arbitrary

3.7.1

choice of Rmin, assuming Rmin and RC to be approximately equal. The curve which

results from this choice of Rmin must fit available space and other field

conditions, and must not cause the available float of any crane using the

track to be exceeded. Upon satisfying these conditions, Rc should normally be

in the range:

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