double-flanged crane [and railroad] wheels. [Provide turntable frogs with
frog angle and rail curvature geometry indicated. Variations will not be
accepted.]
2.2.2.7
Manually-Operated Switch Throw Mechanisms and Housings
**************************************************************************
NOTE: Manually-operated switch throw mechanisms and
housings are commercially available items and should
be supplied and pre-tested by the switch
manufacturer whenever possible. NAVFAC Definitive
Drawing No. 1404353, "Portal Crane Track Switch
Throw Linkage," contains definitive details for a
manually operated throw mechanism but may not be
similar to commercially available units. If
paragraph entitled "Power-Operated Switch Throw
Mechanism" is used, then paragraph entitled
"Manually-Operated Switch Throw Mechanisms and
Housings" must be used.
The power throw mechanism shall utilize a hydraulic
linear actuator of a manufacturer's standard design
employing an electric or air-driven motor pump.
NAVFAC Definitive Drawing No. 1404354 "Portal Crane
Track Switch Power Mechanism" and 1404355 "Portal
Crane Track Turntable Frog Power Mechanism" contain
definitive details for the layout of a
power-operated switch throw mechanism but may not be
similar to commercially available designs. The
minimum performance characteristics for the NAVFAC
Definitive Design power throw mechanisms are as
follows:
Turntable Frog:
Stroke:
300 mm (12 inches) 12 inches
Speed: 20 mm/s (3/4 inches per second) 3/4 inches
per second
Force: 5 kN (1200 pounds) 1200 pounds working:
70
kN (16,000 pounds) 16,000 pounds maximum
Switch Points:
Stroke:
250 mm (10 inches) 10 inches
Speed: 20 mm/s (3/4 inches per second) 3/4 inches
per second
Force: 13 kN (3000 pounds) 3000 pounds working:
187 kN (42,000 pounds) 42,000 pounds maximum
Satisfactory commercially available power throw
mechanisms for certain site specific crane rail
switches have recently been installed at:
Puget Sound, Naval Shipyard, Bremerton, Washington
SECTION 14606N
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