Premiere at interlift: Mechatronic Safety Gear

Cobianchi has developed new mechatronic safety gear with integrated safety electronics. The Swiss company will be unveiling this safety gear at the interlift.

By Dr Stephan Rohr

The original task of safety gear was to prevent a crash in the event of the rope breaking. This was because in the early era of lifts, hemp ropes were still used, which were quick to break when improperly handled or under excess strain. For this purpose, the safety gear was connected to the speed governor with its own rope. The speed governor blocked at a preset speed and the safety gear was retracted to prevent a crash.

Initially, this principle remained unchanged. However, at higher speeds instant safety gear can no longer be used due to its design. As a result, instant blocking safety gear underwent further development into progressive safety gear. Instant safety gear creates a block by means of a roller on an inclined plane until a complete halt is achieved.

Excessive overloading leads to the destruction of such instant safety gear. Consequently, at higher speeds operation occurs with preset brake deceleration in order to bring the car to a standstill.

Safety brake prescribed on drive

Figure 2 shows a mechatronic heavy duty system that is synchronised solely by means of cable connection in the same installation space.

Annex A3 was added to the then valid EN 81-1 in 2009. This prescribes a safety brake on the drive, which is intended to prevent the car from leaving the landing with open doors.

The ideas was to prevent the encoder shafts on the drive from breaking, which could result in the drive accelerating uncontrollably and people being injured in the case of mechanically-opened and electrically-bridged doors.

A retrofit solution was developed for lift systems in which no safety brake was built into the motor. This retrofit solution consists of a bolt attached to the speed governor. This bolt blocks the speed governor as soon as the car moves uncontrollably. This results in activation of the safety gear that stops the car if the door is open.

And the Pessral arrived … 

PESSRAL was mentioned for the first time in the EN 81-1 of 2005. This created the option of also performing previously mechanically-implemented safety functions electronically. In the following years, it was initially the large lift manufacturers which introduced PESSRAL systems. Finally, in 2011 the first certified absolute positioning system was introduced, which also integrated safety functions, Familiar providers of such systems are Cedes, Elgo ,Kübler and New Lift.

If the safety gear is triggered by one of the above-mentioned PESSRAL systems instead by a speed controller which can only react in the event of excess speed, numerous new functions are realisable.
• shortened shaft head/-pit or pre-triggered stopping system
• unintended car movement (UCM) • excess speed
• monitoring during inspection at reduced speed (compared to the rated speed, big differences can arise particularly in high-rise lifts).
• different upwards- to downwards speed
• electric coupling of safety gear as a result of which synchronisation bar linkages can be dispensed with.
• platform protection
• assembly operation protection

There are even more functions one will in future be able to protect with safety gear.

Health status of the safety gear?

However, one issue holds a growing risk: during the development of safety gear, attention was previously only paid to protection against excess speed or of the safety area. However, if an increasing number of safety functions are now protected by the safety gear, knowing the “health status” of the safety gear is absolutely necessary.

This should not just emerge during the annual inspection but there should instead be immediate feedback. After all, you want to know immediately if the just-activated safety area monitoring is also working since if it fails, people are directly threatened.

Integrated safety electronics

Figure 3 shows two single mechatronic attachment heads

Cobianchi’s new mechatronic safety gear features integrated safety electronics. As a result, important key values can be generated, which were previously unavailable. 
• At what point was the safety gear (initially) triggered?
• Was the safety gear triggered completely or only partially?
• How much wear reserve remains?
• Is the safety gear still correctly mounted on the rail? 

Genuine electronic synchronisation of the attachment heads occurs using communication between the attachment heads. This is in particular an option when using several attachment heads (up to twelve), which prevents the car getting into an inclined position if individual attachment heads are only partially retracted or one attachment head retracts improperly.

The monitoring is not only simplified by the new mechatronic safety gear but can also be connected to cloud systems. As a result, completely new options open up, especially for heavy duty systems.

The author is managing director of Cobianchi and chairman of the Board of Management.

More information: cobianchi.ch

Cobianchi at the interlift 2025: Hall 3C, Stand C204