Every experienced rigger knows the feeling: the crane holds still, the load is almost in position, and then it drifts — sideways, or it rotates, or it tips slightly on the hook. None of that is wrong. It is exactly what physics predicts for a heavy rigid mass hanging from a flexible suspension system.
Why Steel Loads Swing
A suspended load behaves like a pendulum. The hook is the pivot, the sling is the arm, the load is the weight at the end. Anything that introduces a sideways force — crane travel, a gust of wind, the load coming off a surface unevenly — causes the load to swing. Once it starts, it takes time to stop. Air resistance on a heavy steel load is very small relative to its mass, so that swing energy bleeds away slowly.
This is why a load can still be swinging gently when it arrives at its destination, even if the crane stopped moving some time ago. That residual swing is what puts the worker's hand in the hazard zone when they reach in to stop it.
The correct response to swing
Taglines are the correct engineering control for managing swing during the early and mid-stages of a lift. At full tagline length the operator stands well clear of the swing arc while still applying enough directional force to damp the pendulum motion. As the load approaches final position, a push-pull tool takes over for the close-range fine correction the tagline's long lever arm cannot provide.
Why Steel Loads Rotate
Rotation — the load slowly turning on the hook — is governed by rotational inertia. Once a mass starts turning, it keeps turning until something stops it. Steel loads have very little to stop them: air provides almost no resistance, and the hook-and-sling provides almost no rotational friction. Rotation can start from wind, residual torque from pickup, or brief contact with an adjacent surface during descent — and once started, it will often continue throughout the positioning sequence.
The correct response to rotation
Rotation is the behaviour that most directly benefits from a magnetic push-pull tool with a wide articulation range. A magnetic head attached to the load's surface applies a controlled rotational correction while the operator stands at a safe working distance. Taglines provide only coarse rotational control at close range.
Why Steel Loads Drift
Drift is the combined term for swing, settling angle, and rotation all happening at once — so that the load's position and orientation continue to change even after the crane has stopped moving. Drift also includes the load settling to its natural hanging angle based on its centre of gravity distribution, which is rarely exactly where the rigging attaches. An asymmetric load hangs slightly tilted the moment it leaves the ground, and that tilt needs correction before it can be set down cleanly.
The correct response to drift
Drift is why the final positioning phase requires a worker to apply a controlled, directional force. The engineering question is how: with the hand directly on the load, or through a tool that keeps the hand at a safe working distance? The Last 300 mm Rule™ defines the zone where that answer matters most.
The crane closes the major distance. The last 300 mm — where the component is guided into its final position — belongs to the worker. That is where the hand exposure lives. Engineering that final zone with the right tool is what the Load-It® MagHead system is designed to do.
Sequencing the Controls
- Early and mid-lift: tagline for gross swing and orientation control from full standoff distance.
- Final approach: magnetic or mechanical push-pull tool for fine correction, rotation control, and precise positioning with the hand kept clear.
- Landing: crane supports the load throughout; the push-pull tool guides the final seating without hand contact at the closing gap.
The tools are complementary, not competing. Using both in their correct phases is not redundancy — it is correct sequencing.
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