MotoSuiveur® Load Arrest System

Safety assurance in high-risk lifting operations

The MotoSuiveur load arrest system protects against uncontrolled loads caused by hoist brake, gearbox, motor or control system failures, including overspeed, overload and double blocking scenarios.

Rapid, failsafe and damped arrest within 30° of drum rotation
No reliance on conventional active detection systems
Mechanically passive – holds the load securely
Compact and hoist-independent
Replaces costly SIL safety circuits
Allows for multiple safe methods of load recovery
Optional integrated load recovery

We are proud to work with our partners, SIGUREN Technologies, to bring MotoSuiveur to our UK customers.

Importantly, MotoSuiveur meets the recommendations of the Office for Nuclear Regulation’s ONR Technical Assessment Guide 56 (TAG 56) for Nuclear Lifting Operations in mitigating a range of nuclear lifting risks.

MotoSuiveur brings these benefits to all sectors of industry, protecting people and assets.

The MotoSuiveur load arrest system

The MotoSuiveur load arrest system consists of four main elements:

The MotoSuiveur device – this is a worm and wheel mechanism attached to the hoist drum, which ‘follows’ it in normal operation (‘MotoSuiveur’ means ‘motor follower’ in French)
The control system – links the MotoSuiveur device with the hoist controls, ready for safe operation
An optional torque limiter – possible thanks to the MotoSuiveur device creating a second kinematic chain to hold the load
An optional load recovery drive – for remote recovery in radiological environments.

Protects against uncontrolled load scenarios

Uncontrolled loads are often mitigated by the use of emergency calliper hoist brakes.

However, there is an inherent delay in the fault detection and activation of calliper brakes, leading to a significant drop height before the load is arrested.

This is not the case when using the MotoSuiveur. Its mechanically locking design activates nearly instantly, arresting the load within just 30° rotation of the hoist drum.

This provides the following protection:

Kinematic chain failure
Any overspeed or sudden acceleration rapidly trigger the MotoSuiveur load arrest, halting the drum
Mitigates against brake, motor, and gearbox failures
Load is held safely for recovery to the floor, independent of the hoist

Control system failure
The MotoSuiveur acts independently of the hoist, bringing any sudden increases in speed or acceleration to a damped arrest
The load is held safely in place, ready for recovery

Overload protection

An optional torque limiter delivers additional protection of the load, hoist and crane structure.

A second kinematic chain is created when a MotoSuiveur device is attached to the hoist drum. This facilitates the inclusion of a torque limiter between the hoist motor and gearbox.

The torque limiter converts unwanted hoist motor energy to heat, protecting the kinematic chain and crane structure without losing load path integrity.

Overload protection
The torque limiter protects against overloads, restrained loads and snagged loads
The load is arrested and held safely in place, ready for recovery

Double blocking protection
The torque limiter prevents the forces generated by the motor from causing damage in a double blocking scenario
The load is arrested and held safely in place, ready for recovery

Safe, rapid and damped load arrest

The MotoSuiveur load arrest device consists of a worm and wheel mechanism mounted directly to the hoist drum.

The worm – which communicates directly with the MotoSuiveur control system – creates a permissive system that only allows hoisting operations if fully functional and healthy.

The system only allows the hoist barrel to rotate at a speed within normal operating parameters. As the wheel is attached directly to the hoist barrel, any difference in speed or acceleration outside of those parameters will drive the wheel into the worm, causing it to mechanically lock. This provides mechanically and electrically independent failsafe protection in the event of a failure in the hoist’s kinematic chain.

The safe and rapid arrest of the load is also damped by the worm’s hydraulic chamber, absorbing any transient shock loading.

The load is brought to a safe stop within 30° rotation of the drum. Dependent on rope and barrel configurations, this could translate to a load drop height of just 30mm before arrest.

Compare this to traditional hoist safety brakes and the difference can be substantial.

Passive protection, permissive operation

Passive protection
MotoSuiveur protects through simple mechanical action – if the hoist drum rotates faster than the worm can follow, the system gently locks.
Permissive operation
If the worm has been moved to an incorrect position by the wheel, hoist operation is prevented.
Minimal drop height
If triggered, the damped action of the worm arrests the load within 30° rotation of the drum, or as little as 30mm of drop height in typical applications.

Remote load recovery

When an arrested load is held safely by the worm and wheel, MotoSuiveur allows a number of recovery options.

One is to co-ordinate the manual release of the hoist brake (feathering) with the rotation of the worm. This safely allows gravity to bring the load down.

However, in nuclear facilities, it is not always possible to approach the hoist to perform manual brake operations.

An optional integrated independent recovery motor is available that reverse drives the worm and wheel mechanism, remotely lowering the arrested load to ground. This is the safest and quickest method of arrested load recovery.

See MotoSuiveur in action

Experience the MotoSuiveur load arrest system up close, in person.

You will see how the innovative design of MotoSuiveur has revolutionised hoist and crane safety.

You can get hands-on with our demonstrator unit to really understand how it works, and how it delivers so many safety benefits to nuclear lifting operations.

Follow the link below to arrange a demonstration.

MotoSuiveur customer applications

FED retrieval mast and manipulator

10m telescopic mast and 5m reach manipulator, fitted with MotoSuiveur load arrest device
5t hoisting system for nuclear size reduction tasks
Remote control operation, plus independent load recovery paths