Safety Order: Setup of Mueller deropement switches on combination or "Rosta" sheave assemblies

Safety Order

Safety Order: Setup of Mueller deropement switches on combination or "Rosta" sheave assemblies

May 6, 2010

Safety Order
Passenger Ropeways

Reference Number:

SO-P4 050216 1

This safety order is being issued pursuant to section 31 of the Safety Standards Act. A person affected by this safety order may appeal this order, in writing, to the Safety Standards Appeal Board in accordance with Section 51 of the Safety Standards Act. It is an offence under section 72 to not comply with a safety order.

Part 1: Details of regulated work or regulated product

This safety order is being issued in relation to (circle or highlight one):

Regulated Work – General

Regulated Products – General

Regulated Work – Specific Class

Regulated Product – Specific Class

Specific Regulated Work

Specific Regulated Product

A failure of a deropement switch to detect a full deropement on a Mueller 2 + 1N combination or “Rosta” sheave assembly installed on a double chairlift was reported to the BCSA. It has been determined that this switch was setup incorrectly and did not meet the manufacturer’s requirements for proper setup. The factors which led to   the deropement detection failure were incorrect actuator to brittle bar or break fork clearance and possible incorrect preloading of the “Rosta” sheave arm rubber element.  In this configuration the fracture of the brittle   bar or break fork is reliant on sufficient travel of the actuating mechanism attached to the “Rosta” sheave arm.

Part 2: Requirements(s) of this safety order

Effective immediately all operators of Mueller passenger ropeway installations, including surface ropeways,  which have the above noted sheave assemblies and/or similar combination sheave configurations which rely on movement of the upper “Rosta” sheave arm for deropement detection shall take the following action:

  • Ensure correct clearance of actuator bolt on “Rosta” support arm to deropement switch brittle bar or break fork as per manufacturer’s requirements
  • Ensure correct preloading of “Rosta” sheave support arm rubber element as per manufacturer’s requirements
  • Complete attached response form and fax to Safety Officer when requirements are complete

These requirements shall be completed within the next 24 hours or the installation shall be shutdown until these requirements can be completed. For clarification on the correct setup of these components please contact your manufacturer. Any requests for clarification on the interpretation of this safety order can be made to your Safety Officer.

Part 3: Details of issue (if applicable)

All contractors operating Mueller passenger ropeway installations.

Part 4: Details of ordering Safety Manager or Safety Officer

I certify that I am authorized to issue this safety order in accordance with section 15(d) of the safety Standards  Act or that I have been delegated this power under section 15(g) of the safety Standards Act. I herby order that this safety order be complied with by persons effective the date of this safety order under the authority granted by those sections.



Tom Hamilton

Provincial Safety Manager, Passenger Ropeways and Amusement Rides British Columbia Safety Authority

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