'McDonald Truss' Bridge Kit

timber structure kit with bronze truss rods, track supports & deck planking!

(1:48, 1/4" to the foot, O scale or Narrow Gauge, On30) 

This interesting project was recently completed in the workshops of our 'Bulahdelah Alum & Timber Company'. After numerous requests for more structure kits, we have developed an attractive and versatile truss bridge kit and packed it with interesting features. Our 1:48 scale bridge design offers amazing strength and rigidity with laminated timber under compression and phosphor-bronze rods under tension (as per prototype) with over 150 Nut/Bolt/Washer detail sets!

Use it as a railway bridge or road bridge as we supply you with additional lengths of heavy track support beams and lightweight deck planking timbers. Use it for your O scale or On30 railway applications, with or without the deck planking.

 
See our Ebay Store 'Steam in the Bush' for mining equipment, skeleton log cars & disconnects, On30 and HO steam locomotives, our sensational dress-up kits for your On30 Shay, Climax and Porters, flat car loads and many more items, all at Buy it Now!

Bridge Dimensions:

• Height:
  • external: 3 inches (75 mm), (12 feet proto)
  • internal: no restriction
   
• Width:
  • external: 6 inches (150 mm) (24 feet proto)
  • internal: nominal 3 inches (75 mm), (12 feet proto)
  • Note: internal clearance can be made wider
   
  
• Length:
  • overall (maximum): 1' 9" (550 mm) (84 feet proto)
  • 3 alternative span widths (nominal):
    
  • 1) 1' 6" (460 mm) (72 ft proto)
  • 2) 1' 4" (410 mm) (64 ft proto)
    
  • 3) 1' 2" (355 mm) (56 ft proto)
   
  
• Compression Timbers:
  • Top Chord: 18" x 18" (proto)
  • Bottom Chord: 24" x 24" (proto)
  • Corbels: 18" x 6" (proto)
  
  
• Tension Rods: 1.5" diameter (proto)

• Nut/Bolt/Washers: 2.5" nut on a 6" washer (proto)

Kit Includes:

• heavy construction beams
• phosphor bronze & brass tie rods
• optional railway track supports
• optional deck planking
  
• optional deck planking edge beams
• 150 styrene Nut/Bolt/Washer detail sets
• comprehensive plans and instructions
• full size (1:1) construction templates
  

Prototype History:

Our 1:48, O scale McDonald Truss Bridge is based on a prototype across Cox's River at McKanes Falls near Lithgow in New South Wales. Completed in 1893, the Heritage Listed structure is one of the oldest timber bridges in NSW and is significant as a surviving example of one of the largest of the type ever constructed in NSW.

This classic 1880's design by John A McDonald was developed to solve maintenance problems of earlier Public Works Department designs which used single, heavy timbers. Replacement of individual hewn timbers was problematic without demolishing the bridge!

Prototype McDonald Truss advantages:

• easy to build and maintain
• based on a proven 400 year old European design
• used readily available heavy sawn timber beams
• easy replacement of individual timber beams  
• high load capacity
• three possible span lengths

See our Ebay Store 'Steam in the Bush' for mining equipment, skeleton log cars & disconnects, On30 and HO steam locomotives, our sensational dress-up kits for your On30 Shay, Climax and Porters, flat car loads and many more items, all at Buy it Now!