How Spherical Head Anchors Work in Precast Concrete Lifting
Precast concrete construction relies on efficient manufacturing, handling, transportation, and installation processes. Since concrete elements are often produced off-site and transported to construction locations, reliable lifting equipment is essential for handling them safely and efficiently. Concrete lifting anchors play an important role in this process by providing secure connection points between precast concrete elements and lifting equipment.
Among the various lifting solutions available, spherical head anchor systems are widely used for lifting and handling precast concrete components. These systems combine cast-in lifting anchors with specially designed lifting clutches to provide a practical connection for handling different types of concrete elements.
In this guide, we explore the different types of precast concrete lifting anchors, their components, working principles, applications, and key considerations when selecting a suitable lifting system.
What Is a Spherical Head Anchor System?
A spherical head anchor system is a type of precast concrete lifting system designed to provide connection points for lifting and handling prefabricated concrete elements.
The system uses specially designed anchors embedded into concrete during the casting process. Once the concrete has hardened, a compatible lifting clutch connects to the exposed anchor head, allowing lifting equipment to raise and move the concrete component.
Unlike general lifting hooks or external attachment devices, these lifting anchors are integrated into the concrete element during production. This provides designated lifting points and allows precast manufacturers to plan handling operations according to the dimensions, weight, and design of each component.
A typical spherical head anchor system consists of five main components: Pin Anchor, Double Head Anchor, Eye Anchor, Spherical Head Lifting Clutch, and Recess Former.
Main Components of a Spherical Head Anchor System
Each component has a different function in the lifting process. Understanding their roles helps precast concrete manufacturers select and use the appropriate lifting devices for their applications.
Pin Anchor
The Pin Anchor is an embedded lifting component used to create a designated lifting point in precast concrete elements. It is installed in the formwork before concrete is poured, allowing the anchor to become integrated into the concrete during casting.
Its design provides a connection point for the corresponding spherical head lifting clutch. Depending on the product specifications and installation requirements, pin anchors can be used in different precast concrete lifting applications.
Double Head Anchor
The Double Head Anchor is another type of embedded lifting anchor used in precast concrete construction. It features two enlarged head sections connected by a central shaft, providing a mechanical anchoring arrangement within the concrete.
The anchor is positioned before casting and becomes embedded as the concrete hardens. Its configuration makes it suitable for specific lifting applications where the corresponding anchor design and installation conditions are required.
Eye Anchor
The Eye Anchor is an embedded lifting component designed for precast concrete handling applications. Its eye-shaped configuration provides a designated connection point for the compatible lifting equipment.
Like other cast-in lifting anchors, it is positioned in the formwork before concrete placement. The surrounding concrete provides the anchorage needed to transfer lifting forces during handling.
The selection of an Eye Anchor depends on the concrete element's design, lifting requirements, and the technical specifications of the anchor.
Spherical Head Lifting Clutch
The Spherical Head Lifting Clutch is a removable lifting accessory designed to connect the embedded anchor to external lifting equipment.
It engages with the corresponding anchor head to establish a mechanical connection for lifting. The clutch transfers the lifting force from the crane, chain, or other lifting equipment through the anchor and into the concrete element.
Unlike the embedded anchors, the lifting clutch can be disconnected after the concrete element has been positioned and reused for subsequent lifting operations, provided it passes the required inspections.
Compatibility is essential when selecting a lifting clutch. The clutch must match the corresponding anchor system and rated load capacity. Using incompatible lifting accessories can compromise the lifting connection.
Recess Former
The Recess Former is used during concrete casting to create a recessed area around the lifting anchor head.
It is positioned together with the anchor before concrete is poured. Once the concrete has hardened and the formwork is removed, the recess former can be removed according to its design, leaving an accessible space around the anchor head.
This recessed area provides sufficient access for connecting and operating the spherical head lifting clutch. It also helps accommodate the lifting connection without leaving the anchor head completely exposed on the concrete surface.
The recess former is therefore an important part of the system, helping ensure that the anchor can be accessed and connected during subsequent lifting operations.
How Does a Spherical Head Anchor System Work?
A spherical head anchor system works through the coordinated use of embedded anchors, recess formers, and removable lifting clutches. The process begins during precast concrete production and continues through handling and installation.
Anchor and Recess Former Installation
The selected lifting anchor and corresponding recess former are positioned inside the formwork according to the approved lifting design. Correct positioning is important to ensure that the anchor remains accessible after concrete casting.
Concrete Casting and Curing
Concrete is poured into the formwork, surrounding the embedded anchor. After the concrete has been placed and cured to the required strength, the formwork and recess former are removed as specified.
Lifting Clutch Connection
The spherical head lifting clutch is connected to the exposed anchor head through the recessed opening. The connection must be checked to ensure that the clutch is correctly engaged with the compatible anchor.
Lifting and Handling
The lifting clutch is connected to the crane or other lifting equipment. When lifting force is applied, it is transferred through the clutch and anchor into the concrete element, allowing it to be raised and moved.
Clutch Removal
After the concrete element has been safely positioned and supported, the lifting clutch can be disconnected and prepared for reuse.
The complete lifting operation must follow the manufacturer's instructions and an appropriate lifting plan. Concrete strength, anchor positioning, load distribution, lifting angles, and the condition of all lifting components must be considered.
Applications of Precast Concrete Lifting Anchors
Precast concrete lifting anchors are used in various construction and infrastructure projects. They provide designated lifting points for concrete elements manufactured away from the construction site and subsequently transported for installation. Common applications include:
Precast Concrete Wall Panels
Wall panels are frequently manufactured in precast facilities before being transported to construction sites. Concrete lifting anchors provide connection points for demoulding, handling, transportation, and installation.
Precast Beams and Columns
Structural beams and columns require suitable lifting arrangements to accommodate their weight and center of gravity. The appropriate anchor type and positioning depend on the component's dimensions and lifting design.
Precast Floor Slabs
Lifting anchors and other lifting inserts are used to handle floor slabs during production and installation. Their positioning must account for the slab's geometry and the required lifting configuration.
Precast Infrastructure Components
Concrete barriers, culverts, manholes, and other prefabricated infrastructure components may also require lifting anchors for handling and transportation.
The selection of concrete lifting devices depends on the specific application, component design, and required lifting capacity.
EATHU Precast Concrete Lifting Anchor Systems
EATHU supplies precast concrete lifting anchors and accessories for different requirements in the precast concrete industry. Our spherical head anchor system includes Pin Anchors, Double Head Anchors, Eye Anchors, spherical head lifting clutches, and recess formers.
The lifting clutch range covers six load groups, with rated capacities from 1.3 to 32 tonnes, supporting different precast concrete lifting requirements. Selected components are available with different surface treatments, including black finish, zinc plating, and hot-dip galvanizing, depending on the product type.
By supplying the main components of a spherical head anchor system, EATHU provides precast concrete manufacturers with compatible lifting products for their production and handling operations.
For more information about our precast concrete lifting anchors, lifting clutches, and accessories, contact EATHU to discuss your project requirements.