“Freyssi Flat Jacks: The Compact Powerhouses of Precision Lifting and Load Transfer”

In the realm of heavy construction, civil engineering, and structural support, few tools offer the versatility and precision of Freyssi Flat Jacks. Supplied by WB Equipment, these highly specialized devices are pivotal in many critical applications, from bridge repairs to structural prestressing. Compact yet powerful, Freyssi Flat Jacks are designed to operate in confined spaces while delivering considerable force—making them indispensable across a variety of industries in the United States.

What Are Freyssi Flat Jacks?

Freyssi Flat Jacks are hydraulic devices used to apply force or displacement in tight, restricted areas where traditional jacking systems won’t fit. Unlike bulky hydraulic cylinders, Flat Jacks are thin, plate-like assemblies that can be easily inserted between concrete or steel components. Once inflated with hydraulic pressure, they exert controlled force to lift, level, or preload structures.

They are not mechanical—they operate exclusively on hydraulic principles. However, once inflated and the desired load is transferred or the position is adjusted, a mechanical shim (steel packing plates) is often used to lock the position permanently after the hydraulic pressure is released. This synergy of hydraulic force and mechanical locking makes them uniquely effective.

How Do They Work?

Freyssi Flat Jacks consist of two flat steel plates that are welded around the edges and connected to a hydraulic input. When pressurized with hydraulic fluid—typically via a manual or powered pump—the plates are forced apart, applying linear force in a precise and controlled manner. The amount of expansion is limited, usually to a few millimeters, but the pressure they can exert reaches thousands of psi.

Once the desired adjustment is made, the jack can be locked in place using shim plates, and the hydraulic pressure can be safely removed. This makes them ideal for both temporary and permanent applications.

Typical Applications: Where and How They’re Used

Freyssi Flat Jacks are used in a wide array of applications, such as:

• Preloading and prestressing structural members (beams, columns, and joints).

• Load transfer in bridge bearings or support realignment.

• Structural lifting or repositioning in tight access areas.

• Controlled load application in laboratory testing and mockups.

• Concrete repairs, particularly in tunnels and dams.

They are often installed in the annular space between structural components and used to apply force gradually and evenly. Once the load is transferred, steel shims are inserted and pressure is released to leave a permanent support condition.

Accessories Needed

Freyssi Flat Jacks typically require a few key accessories for optimal operation:

• Hydraulic hand pump or power pack: For delivering hydraulic fluid at high pressures.

• Pressure gauge: For monitoring and controlling applied pressure.

• Steel shims or packers: Used to maintain structural support after the jack is depressurized.

• Flexible hoses: To connect the jack to the pump, especially useful in difficult access situations.

• Protective housings (optional): For embedding or long-term installation in harsh environments.

WB Equipment provides these accessories as part of their system offerings, ensuring customers get a complete and ready-to-use solution.

Industries Using Freyssi Flat Jacks in the USA

A wide range of industries in the U.S. rely on Freyssi Flat Jacks, including:

• Construction and Civil Engineering: For bridge bearing replacements, column repairs, and wall realignments.

• Transportation Infrastructure: In rail and highway systems for bearing adjustments and support structures.

• Power Generation: For maintaining dam gates and nuclear facilities.

• Mining and Tunneling: Where precise lifting or pressure application in confined areas is necessary.

• Marine and Offshore: For underwater foundation and structural maintenance.

• Architecture and Historical Preservation: To gently reposition or support fragile structures during restoration.

Interesting Facts and Advantages

• Invented by Eugène Freyssinet, a pioneer in prestressed concrete, the Flat Jack concept dates back to the mid-20th century and is still in use globally.

• Because of their flat design, they can be embedded directly into concrete structures and even grouted into place for permanent support.

• They allow accurate pressure control, ensuring safety and consistency in critical structural applications.

• Freyssi Flat Jacks are often used in tandem, allowing multiple points of control and load balancing.

• They can be manufactured in custom sizes, which WB Equipment can facilitate for unique project needs.

Final Thoughts

Freyssi Flat Jacks, especially those provided by WB Equipment, offer a powerful solution for tasks that demand precision, strength, and compact design. As infrastructure across the United States ages and requires reinforcement, tools like these become ever more critical. Whether you’re supporting a historic structure, lifting a bridge bearing, or stress-testing a concrete beam, Freyssi Flat Jacks bring precision engineering right where it’s needed most—quietly performing under pressure.