The shoring U head jack base is a critical component in temporary support systems, designed to transfer vertical loads from formwork or falsework to the ground or underlying structure. It consists of a threaded adjustment mechanism housed within a U-shaped steel head that engages with timber or steel beams, allowing precise height control and load distribution. Unlike fixed supports, this system accommodates site variations and construction tolerances through manual adjustment, making it essential for applications requiring staged loading or intermittent access.
Manufactured from hot-rolled structural steel, the base plate distributes reaction forces over a sufficient area to prevent soil punching or slab damage. The U head geometry ensures lateral stability of the supported member while minimizing stress concentrations at the contact point. Threaded spindles, typically ACME or trapezoidal profile, provide mechanical advantage for fine adjustments under load, with corrosion-resistant coatings applied to extend service life in harsh environments.
| Parameter | Typical Value | Notes |
|---|---|---|
| Base Plate Dimensions | 150x150mm to 200x200mm | Customizable based on ground bearing capacity |
| U Head Width | 100mm (standard for 2x4 timber) | Accommodates nominal 45x95mm or 50x100mm members |
| Spindle Thread Type | ACME or Trapezoidal | Ensures self-locking under vibration |
| Adjustment Range | 300–500mm stroke | Depends on spindle length and nut travel |
| Safe Working Load (SWL) | Up to 25 kN | Verification required per project design |
| Surface Treatment | Hot-dip galvanized or powder coated | Minimum 55µm zinc coating for corrosion resistance |
The main body is fabricated from S235JR or equivalent structural steel plate, cut and formed to ensure dimensional stability under cyclic loading. The U head is pressed or welded to maintain perpendicularity with the spindle axis, critical for preventing eccentric loading. Spindles are machined from C45 steel bar, hardened to 25–30 HRC at the thread roots to resist wear while retaining toughness. Nuts are produced from ductile iron or forged steel, designed to prevent galling during adjustment under load.
Base plates feature drainage slots or chamfered edges to prevent water pooling and facilitate cleaning. Welds are continuous fillet or full-penetration where stress concentrations occur, inspected visually and via magnetic particle testing for critical joints. All components undergo pre-assembly verification to confirm smooth spindle rotation and proper nut engagement before coating application.
These bases are primarily used in slab formwork systems where soffit elevation must be adjusted to match structural tolerances or accommodate camber in beams. In bridge falsework, they support longitudinal beams beneath deck pours, allowing incremental lifting during multi-stage casting. The adjustability compensates for foundation settlement or temporary support deflection, reducing the risk of overstressing formwork components.
In renovation projects, U head jack bases enable temporary propping of existing slabs during wall removal or opening creation, where precise load transfer is essential to avoid cracking. They are also employed in shoring trenches or pits, supporting lagging or soldier piles where ground conditions vary along the excavation perimeter. The modular nature allows reconfiguration as excavation progresses, unlike fixed-height systems.
For heavy-load applications such as transfer girder installation or column jacking, multiple units are arranged in grids with load-distributing beams, enabling synchronized lifting through turnbuckle-operated systems. The U head prevents beam roll-over while the threaded mechanism allows micro-adjustments to achieve even load sharing across all supports.
Base plate dimensions can be increased for low-bearing-capacity soils, such as soft clay or fill material, to reduce contact pressure below allowable limits. U head widths are adjustable to accommodate non-standard members, including steel channels, I-beams, or laminated timber, with custom saddles or liners available upon request. Spindle lengths are variable to suit deep formwork or restricted access areas where standard stroke is insufficient.
Thread types can be switched to metric trapezoidal or imperial ACME based on regional equipment compatibility. Surface treatments include epoxy primers for chemical exposure environments or stainless steel cladding for marine applications. Optional features include swivel bases for inclined surfaces, toe-board brackets for safety compliance, and captive nuts to prevent disassembly during handling.
Incoming steel is certified with mill test reports verifying chemical composition and mechanical properties. Dimensional inspections confirm U head perpendicularity, spindle straightness, and base plate flatness using calibrated gauges and coordinate measuring machines. Thread profile is checked via go/no-go gauges to ensure proper engagement and self-locking characteristics under vibration.
Load testing is performed on sample batches using hydraulic presses to validate SWL ratings, with deformation measured at 25%, 50%, 75%, and 100% of test load. Coating thickness is verified via magnetic induction or ultrasonic methods, with adhesion tested per ASTM D3359. Final assembly includes functional checks: smooth rotation, absence of binding, and proper nut retention under simulated load cycles.
Traceability is maintained via batch numbers etched or stamped on non-critical surfaces, linking each component to material certificates and test records. Packaging includes corrosion inhibitors and separation layers to prevent surface damage during transit, with units bundled in quantities optimized for handling and storage.
Standard configurations with galvanized finish and 400mm adjustment stroke are typically available from stock, with lead times of 5–7 business days for domestic orders. Customized units require engineering review of load calculations, base plate sizing, and spindle length, extending lead time to 10–15 weeks depending on material availability and coating complexity.
Quotations require project-specific data: expected load per support, adjustment range needed, base plate constraints (if any), environmental conditions (exposure to chemicals, salt, etc.), and preferred surface treatment. Providing formwork member dimensions ensures correct U head sizing. For export shipments, packaging complies with ISPM 15 standards, and documentation includes material certifications, test reports, and country-of-origin declarations.
To request a quotation or discuss technical requirements for your shoring system, provide your project’s load specifications, adjustment needs, and site conditions. Our engineering team will review the details and respond with a detailed proposal, including dimensional drawings, load certificates, and estimated delivery timelines.
Submit Inquiry
