Shock Transmission for Bridge Construction

• Application: Transportation
• Certification: CE, ISO
• Surface Treatment: Yes
• Technics: Forged
• Material: Steel
• Lock Force: 100-3000kn
• Model NO.: HD-STU
• Stroke: -300mm~+300mm
• Velocity: 0~1500mm/S
• Diameter: D100-D1000mm
• Usage: Cable Stayed Bridge,Single Span Bridge
• Transport Package: as Request
• Specification: HD-STU
• Trademark: Haider
• Origin: China
• HS Code: 4016999090
• Production Capacity: 100, 000 Sets/Year

Product Description

Shock Transmission Unit 

Shock transmission unit(STU), also known as Lock-up device(LUD), is basically a device connecting separate structural units.
It is characterized by its ability to transmit short-term impact forces between connecting structures while permitting long-term movements between the structures.
It may be used to strengthen bridges and viaducts, particularly in cases where the frequency, speed and weights of vehicles and trains have increased beyond the original design criteria of the structure.
It may be used for the protection of structures against earthquakes and is cost effective for seismic retrofitting.
When used in new designs large savings can be achieved over conventional construction methods.

The shock transmission unit/lock-up device consists of a machined cylinder with a transmission rod that is connected at one end to the structure and at the other end to the piston inside the cylinder.
The medium within the cylinder is a specially formulated silicone compound, precisely designed for the performance characteristics of a specific project,the silicone material is reverse thixotropic.
During slow movements caused by temperature change in the structure or shrinkage and long-term creep of concrete, the silicone is able to squeeze through the valve in the piston and gap between the piston and cylinder wall. 
By tuning the desired clearance between the piston and the cylinder wall, different characteristics can be achieved. A sudden load causes the transmission rod to accelerate through the silicone compound within the cylinder. 
The acceleration quickly creates a velocity and make the valve closed where the silicone cannot pass fast enough around the piston. 
At this point the device locks up, usually within a half second.