working of hydraulic assisted bridges. various types of movable bridges. hydraulic unit for movable bridges. rolling bridge

1. HYDRAULIC ASSISTED
BRIDGE
Ishan Kossambe
13MCD0038

2. Introduction
• Incorporates an integrated hydraulic system into the
bridge in order to carry more weight
• Suitable for arch based bridges

3. How it works
• Forces in a
lateral/horizontal
direction at the
supports
• Three hinged arch
• Loading will cause the
arch to spread

4. Supports
• Load causes the three
hinged arch to spread
out
• Piston is held in place
via a pined connection
• O-rings of the piston

5. Mid-Span of Bridge
• The high pressure hydraulic fluid causes another piston to
become raised
• Counteracting the load
• Calibration and calculation is required by changing the
diameter of the piston and shafts

6. Advantages
• Little maintenance
• Quantity of material
required to construct
the bridge is reduced
• Increase its aesthetic
and social impact
• Reversal of hydraulic
fluid still results in
equilibrium

7. Disadvantages
• Vertical hydraulic column being required to be located in
the center of the arch
• Vertical column type hydraulic bridges may never be used
in arch bridges required to span gaps which are very high
in the context of the altitude of the locale.
• Failure by very high force

8. Overcoming the Disadvantages
• Eliminating the single
vertical hydraulic
column
• Replacing hydraulic
components placed at
an angle
• Adding several, thicker
O-rings and gaskets

9. Potential Applications
• Pedestrian Footbridges
• Water Transportation
• Vehicular Transportation
• Light Vehicles
• Freight Vehicles
• Railway Transportation

10. Moving Bridges
• Drawbridge
• Bascule bridge
• Curling bridge
• Vertical-lift bridge
• Retractable bridge
• Tilt bridge

11. Hydraulic Systems for Movable
Bridges
•Objectives
• Ability to handle varying loads
• Smooth acceleration and deceleration
• Positive locking in any position

12. Hydraulic Cylinders
• Two per span
• Tie rod and welded
• Intermediate trunnion
and spherical bearing
clevis both ends
• The national fluid power
association (NFPA)
established a standard
for tie rod type hydraulic
cylinders
• Tie rods should be
inspected for corrosion
damage

13. Counterbalance Valves
• Varying loads, wind makes it unbalanced and causes run
away
• A counterbalance valve keeps this condition in check
• Holding the bridge firmly in any position
• Acts as a check valve

14. Proportional Valves
• Smooth acceleration and deceleration
• Gradually increasing or decreasing the amount of flow to
the cylinders
• The use of servo valves for this task is not recommended
• 0 - 9 volts dc/800 milliamps

15. Hydraulic Pump
• Variable volume-bent axis-piston type pump
• Strong suction capability and greater dirt tolerance, make
them a good choice for movable bridge
• Pumps which require a boost or supercharge only add
complexity to the design
• Horsepower limiter

16. Hydraulic Fluids
ISO Grade Viscosity Normal Operating
Temperature
AW32 Light 1O0-150°F
AW46 Medium 3O0-160°F
AW68 Heavy 4O0-170°F

17. Care to be Taken While Designing
• Pumps and motors should be accessible for work
• Vibration mounts and hoses to isolate pump VIBRATION
• The use of ANSI standard bolt pattern sub plate mounted
valves
• Drilled manifolds to minimize piping and fittings
• Filters which are easy to change with good clogging
indicators
• Straight thread "o” ring ports and fittings
• Large access covers for reservoirs

18. The Rolling Bridge
• Completed in 2004 as part of the Grand Union
Canal office & retail development project at Paddington
Basin, London.
• Despite the connotation of its name, it is more accurately
described as "curling".
• Designed by SKM Anthony Hunt with Packman Lucas,
and built by Littlehampton Welding Ltd.
• The Hydraulic design and development was done by
Primary Fluid Power Ltd in the North West.
• In 2005, the bridge won the British Structural Steel Design
Award.

19. References
• http://en.wikipedia.org/
• http://www.designingbuildings.co.uk/wiki/Hydraulic_Assist
ed_Bridges
• www.youtube.com
• Hydraulic systems for movable bridges by Michael A.
Henley