Conveyor Stop/Emergency Stop Pull key Systems


Minewatch’s comprehensive range of conveyor protection devices protect people and plant in quarries, mines, tunnels, processing plants, ports and railway depots worldwide. All Minewatch devices are compatible and can be easily installed by qualified electrical engineers on new or retrofit schemes. The primary stopping device on any conveyor system is the pull cable/wire operated safety switch, now available in compliance to BS EN ISO 13849-I PLe Category 3 standards.

Davis Derby design and manufacture a double-ended stop device, which can be adopted as either a normal stop switch, or wired to function as an emergency stop switch, isolating conveyor movement in the event of incidents. When required to operate as a normal stop switch, the pullkey device can be either, wired and fitted to some or all of the moving parts of conveyor machinery to render them safe.

Alternatively, when required to operate as an emergency stop switch, all the pullkeys internal positive break micro-switches should be used and connected to any/all parts of conveyor machinery.

By connecting up all the micro switches to a certified safety relay, the pullkey system will comply with the emergency stop standards of BS EN ISO 13849-I PLe (Category 3) . To enable a successful emergency stop control, all pullkeys and safety relays must be connected to the machinery it is protecting and to all upstream and downstream equipment, where deemed necessary.



  • ATEX-certified dustproof models available, Group II Category 1D
  • IP65 enclosure & corrosive resistant components
  • Double-ended
  • Cats-eye indication (optional semaphore flag)
  • Easy installation
  • 3 years UK warranty (1 year overseas, from date of supply)


  • Dimensions: 190mm L x 135mm D x 116mm H
  • Fixing Hole Centres: 178mm, 10mm Diameter
  • Weight: 2.2Kg.


All of Minewatch HT 800 Series pullkey range is designed for use in safety critical systems for controlling conveyors. Each key can therefore be used as either a Stop Switch or as a Category 2 or Category 3 Emergency Stop Switch as defined in BS EN ISO 13849-I PLe. All Pullkeys are moulded from high stability UV protected polycarbonate, which is tough and lightweight.

All Pullkeys can be used in conjunction with all our relay control units, or on a control circuit up to 110 volts ac. For systems to comply with emergency stop safety regulations, safety relays* must be used.

* Relays available to order: ICR3 (2 relay output) 23418 (standard relay) SRP1 (Pilz)


Recommended spacing between our pullkeys for taut-wire systems is up to 50 metres maximum (40 metres for Dustproof), in conjunction with pig tails at 3 metre intervals. (However, spacing can be up to 100m maximum [80m dust-proof] when installed on slack-cable/wire installations, in conjunction with pigtails at 2-3m intervals for Normal Stopping).

Incoming and outgoing cables are connected via 2 x 20mm threaded cable entries to the internal 12-way easy-access terminal block. The operating knob is sealed with an O-ring and the lid is fitted with a fully recoverable closed cell silicon gasket.

Each pullkey comes boxed with wiring instructions, and several types can be supplied with the wiring and mechanism. Pre-configured to suit bespoke applications upon request. Manuals are also available on request.

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