What is overwind?

Conveyance arresting in the accidental event of the winder
not stopping the conveyance timeously.

Advantages of the Technogrid® overwind impact
protection system

• Very light initial impact force
  - light catchframe (±400kg per set of Technogrid® strings)
  - progressive energy absorption properties of the
  Technogrid® (refer to force stroke diagram).
• Predictable reaction forces relating to cage and headgear design.
• Technogrids are very narrow and therefore occupy
  minimal space in the shaft steel work.
• Technogrid® can be easily retrofitted to existing mines. Each retrofit is custom designed to suit each application.
• No maintenance requirements (recommend annual
  inspections).

The process involved and the factors that have to be quantified in designing the over/underwind impact protection system

• System inertia
  - winder
  - sheave wheel
  - rope
  - cage/skip (including payload)
  - counter weight
• Stroke area (stopping distance)
  - function of acceptable deceleration
  - rope breaking force
• Impact speed
• Once the total system energy is calculated, the
  appropriate Technogrid® configuration is determined.

  The Technogrids® are always installed in units in series. Additional strings can be added in parallel if required.

• In order to reach a practical solution, it may be
  necessary to adjust the stroke area.

PLEASE CONSULT HORNE FOR TECHNICAL INPUT ON THE DESIGN OF THE OVERWIND ARRESTING
SYSTEM AS THERE ARE MANY CONSIDERATIONS AND APPROACHES TO THIS TYPE OF DESIGN