When you are planning a scaffolding or formwork project, few components matter more than the adjustable jack that sits at the top of your vertical standards. The u head jack — often called a U-head jack base or fork head — cradles timber, LVL, or aluminum beams and lets your crew fine-tune the height of the platform. But before you place an order, you need to know exactly which specifications to check. This guide walks through the key specifications of u head jack base scaffolding components, explains what each number means, and helps you choose the right size for your job.
What Is a U-Head Jack?
A U-head jack is an adjustable support component installed at the top of a scaffolding standard or shoring prop. It consists of three main parts: a threaded rod (solid or hollow), an adjustment nut, and a U-shaped cradle that holds the beam in place. The U-shaped opening keeps the beam from sliding sideways, while the threaded rod allows precise height adjustment so the formwork or platform can be leveled quickly. In a typical setup, the base jack sits on the ground to level the foundation, and the U-head jack works from the top to support the load-bearing beams above.
Key Specifications of a U-Head Jack
Before comparing products, it helps to know the six specifications that define a u head jack:
- Screw rod diameter and length
- U-head (cradle) size
- Base plate size
- Material grade
- Surface treatment
- Weight
Screw Rod Diameter and Length
The threaded rod is the heart of the jack. Common outer diameters are 30 mm, 32 mm, 34 mm, and 38 mm, and the length typically ranges from 400 mm to 1,000 mm, with 600 mm being the most common choice. A longer rod gives you more adjustment range, but it also means you need to maintain enough thread engagement for safe load transfer. Always check the minimum thread engagement required by your local standard before setting the final height.
U-Head Size
The U-shaped cradle must be wide enough to seat the beam securely. Typical U-head dimensions are 150 x 120 x 50 mm and 150 x 185 x 50 mm. The depth of the cradle — usually 50 mm — determines how much of the beam sits inside the head, so match it to the width of the timber, LVL, or aluminum beam you plan to support.
Base Plate Size
The base plate spreads the load over the surface below. Common sizes are 120 x 120 mm, 150 x 120 mm, and 150 x 150 mm, with plate thicknesses from 4 mm to 6 mm. For soft or uneven ground, a larger plate reduces the pressure on the surface and helps keep the scaffold level.
Material Grade
Most jacks are manufactured from Q235 carbon steel, while heavy-duty options use Q355B. Q355B offers higher yield strength, which matters for demanding shoring and formwork applications. If you are not sure which grade you need, ask your supplier for the yield strength and how it affects the safe working load of the jack.
Surface Treatment
Galvanizing protects the steel from rust and extends the service life of the component. The main options are electro-galvanized (a bright, smooth finish), hot-dip galvanized (a thicker coating for outdoor and corrosive environments), and painted. For scaffolding that stays on site for months, hot-dip galvanized is usually the better investment.
Solid vs. Hollow U-Head Jack
U-head jacks come in two basic constructions. Solid models use a solid threaded rod and offer maximum load-bearing capacity, which is why they are common in heavy shoring work. Hollow models use a hollow tube, making them lighter, easier to handle, and cheaper to ship without significantly compromising performance. For most tube and clamp and frame scaffolding jobs, a hollow jack is the practical, cost-effective choice.
U-Head Jack vs. Base Jack
Although they look similar, the two components serve opposite ends of the scaffold. A u head jack is installed at the top of the vertical standard to support overhead beams. A base jack is installed at the bottom, with a flat steel plate resting on the ground, and is used to level the foundation. Many projects need both: the base jack levels the scaffold from below, and the U-head jack supports and levels the beams from above.
Typical Specification Table
To give you a concrete reference, here are the specifications of the U-head jacks and base jacks supplied by Bythai Scaffolding:
| Product | Type | Screw Rod | Base Plate / U-Head | Surface | Material | Weight |
|---|---|---|---|---|---|---|
| Adjustable U-Head Jack (Tube & Clamps) | Hollow | 38 x 4 x 600 mm | 150 x 120 x 50 x 5 mm | Electro-galvanized | Q235 | 3.6 kg |
| Adjustable Base Jack | Solid | 30 x 600 mm | 120 x 120 x 4 mm | Galvanized | Q235 | — |
| Adjustable Base Jack | Solid | 32 x 600 mm | 120 x 120 x 4 mm | Galvanized | Q235 | — |
| Adjustable Base Jack | Solid | 34 x 600 mm | 150 x 150 x 5 mm | Galvanized | Q235 | — |
| Adjustable Base Jack | Hollow | 38 x 5 x 580 mm | 115 x 110 x 5 mm | Electro-galvanized | Q235 | 3.0 kg |
How to Choose the Right U-Head Jack
- Match the screw rod diameter to the inner diameter of your standard or shoring prop.
- Match the U-head width to the width of the beam you are supporting.
- Decide how much adjustment range you need before ordering.
- Choose galvanized for outdoor or humid environments.
- Confirm the minimum thread engagement and the nut stop with your supplier.
- Ask for the safe working load if the jack will carry heavy formwork.
Quality and Standards
Reliable jacks are manufactured to international standards. Look for a supplier that builds to EN and BS standards and runs an ISO 9001 quality system. A well-made jack includes a nut stop that prevents the nut from running off the thread and ensures minimum safe thread engagement. These details are easy to overlook, but they are exactly what keeps a formwork deck safe under load.
Why Source U-Head Jacks from Bythai Scaffolding
Bythai Scaffolding Co., Ltd. is a scaffolding supplier from China serving construction companies, oil and gas firms, and distributors worldwide. We supply complete scaffolding systems — ringlock, frame, tube and clamps, shoring props, planks, and ladders — under one roof. Tell us your u head jack specifications — screw diameter, length, plate size, and finish — and our team will match them exactly. Our jacks are made from Q235 and Q355 steel with electro-galvanized, hot-dip galvanized, or powder-coated finishes, and our factory is ISO 9001 certified with products built to EN and BS standards. With over 10 years of industry experience, OEM capability, and flexible MOQ, we help global partners work more efficiently and safely. You can view our full range of u head jack and base jack products on our website.
Conclusion
Understanding the specifications of u head jack base scaffolding is the first step to a safe, level, and efficient scaffold. Check the screw rod diameter and length, the U-head and base plate sizes, the material grade, and the surface treatment before you buy, and always confirm the safe working load with your supplier. If you are looking for a reliable partner for your next project, the Bythai team is ready to help with a quote.