Freyssi Flat Jacks

“Flat, Fierce, and Forceful: How Freyssi Flat Jacks from WB Equipment Power Precision Engineering”

When it comes to structural engineering, architecture restoration, and load management, sometimes the most powerful solutions are also the slimmest. Freyssi Flat Jacks, supplied by WB Equipment, are a prime example of compact engineering excellence. Their flat, disc-like form may appear modest, but these hydraulic devices are capable of exerting enormous force in the tightest of structural spaces.

Are Freyssi Flat Jacks hydraulic or mechanical? How are they used? What accessories are required? And which industries across the United States rely on them? Let’s explore how these unique tools contribute to safe and effective structural work in some of the most demanding environments.

What Are Freyssi Flat Jacks?

Freyssi Flat Jacks are ultra-thin hydraulic jacks designed to exert high compressive or lifting force in locations with extremely limited space. Unlike traditional jacks that require substantial clearance, flat jacks can be inserted into joints or narrow gaps in masonry, concrete, or steel structures and then inflated to perform tasks such as lifting, preloading, or adjusting alignment.

The core design features two welded steel plates forming a sealed chamber. Hydraulic pressure is introduced into this chamber, causing the plates to separate and exert force outward. This makes the Freyssi Flat Jack fundamentally hydraulic, though mechanical accessories (like wedges or shims) are often used for force transfer or post-operation locking.

How Are They Used?

Freyssi Flat Jacks are incredibly versatile. Here are some of their most common applications:

• Bridge Bearing Replacement: Used to temporarily lift a bridge deck while bearings are changed.

• Structural Realignment: Correcting wall displacement in aging buildings or heritage structures.

• Preloading Concrete Structures: Applying stress to structural elements to simulate live loads.

• Gap Closure: Exerting pressure between two components to close construction gaps or apply clamping force.

• Shoring and Jacking: Providing temporary or permanent support during underpinning operations.

WB Equipment supplies flat jack systems either for short-term projects (rental) or permanent installation, depending on client needs. The jacks can be grouted in place to maintain a continuous force, making them a durable structural element.

Where Are They Used in the USA?

Freyssi Flat Jacks are used nationwide in high-value construction and infrastructure projects, especially where precision and limited access are major concerns. Applications include:

• Historic Building Restoration in cities like Boston, New York, and Philadelphia, where old stone or brick masonry structures require careful realignment.

• Highway and Bridge Maintenance Projects where aging infrastructure demands subtle adjustments without full-scale deconstruction.

• Dams and Hydroelectric Facilities where precise structural tensioning is required under tight environmental constraints.

• Tunneling and Underground Construction, including metro systems and utility tunnels.

Anywhere a jack must fit in less than 2 inches of clearance—Freyssi Flat Jacks are the go-to solution.

Are They Hydraulic or Mechanical?

Freyssi Flat Jacks are hydraulic in nature. They use pressurized hydraulic fluid to create force. However, mechanical elements like shims, plates, or grout are often used to lock the pressure in place or retain force after the hydraulic source is disconnected. In this way, the system is a hybrid—hydraulic in function, mechanical in retention.

Accessories Needed

Using Freyssi Flat Jacks safely and effectively requires the following equipment:

• Hydraulic Pump (Manual or Electric) – To apply pressure to the jack.

• High-Pressure Hoses and Fittings – Rated for pressures typically exceeding 10,000 psi.

• Pressure Gauges – Essential for monitoring and regulating applied force.

• Control Valves – Allow precise control and safe depressurization.

• Steel Shims or Wedges – To lock in the expanded position after pressurization.

• Grouting Systems – Used to fill the jack cavity and maintain permanent load.

WB Equipment offers complete systems, including training, technical guidance, and accessories, all backed by decades of field experience.

Industries That Use Freyssi Flat Jacks in the U.S.

The utility of Freyssi Flat Jacks spans many sectors:

• Construction and Engineering Firms

• Transportation Departments (DOTs)

• Railway and Subway Maintenance

• Civil Infrastructure (Bridges, Dams, Tunnels)

• Historic Preservation and Architectural Restoration

• Industrial Equipment Foundations and Alignment

• Utilities and Power Generation Facilities

In these industries, precision and control over structural load make flat jacks an invaluable tool.

Interesting Facts About Freyssi Flat Jacks

1. Invented by Eugène Freyssinet, a pioneer of pre-stressed concrete, the flat jack was developed in the early 20th century to deliver preloading in confined spaces.

2. Their design allows them to remain embedded in the structure after use, grouted in place to provide a permanent preload.

3. Freyssi Flat Jacks can deliver tons of force with only millimeters of expansion—ideal for delicate or aging structures.

4. They are among the few jacking tools that can be used horizontally, vertically, or upside down, depending on project requirements.

5. WB Equipment is one of few authorized suppliers in North America, offering both rental and permanent solutions.

Why Choose WB Equipment?

WB Equipment offers more than just a product—they offer partnership and expertise. With access to a wide range of flat jack sizes and pressures, full-service rental or purchase programs, and field support, WB ensures that every flat jack application is safe, reliable, and successful.

Their engineers work directly with contractors, architects, and structural consultants to ensure correct sizing, placement, and loading, especially for sensitive projects like historic restorations or major infrastructure retrofits.

Conclusion: Big Strength in a Small Package

Freyssi Flat Jacks from WB Equipment prove that size doesn’t limit strength—in fact, sometimes a flatter profile opens the door to engineering possibilities where nothing else fits. Whether you’re lifting a historic wall by fractions of an inch or preloading a bridge support, these jacks bring hydraulic precision and mechanical reliability together in one of the most elegant tools in structural engineering.