AS 4730.2:2018 pdf free download.Mining-Winding equipment Part 2: Braking systems.
2.4 Strength and durability requirements
The failure of any one component within the braking system shall not affect the ability of the braking system to perform the braking functions. The design specification shall demonstrate this through calculation and appropriate risk assessment of the braking system.
Braking system components and brake paths shall be selected and located to minimize and control hazards including those resulting in deterioration by heat, corrosion, wear and contamination.
The static design factor for critical components shall be —
(a) for axially loaded threaded components, not less than 15; and
(b) for other critical components, not less than 10.
The fatigue reserve factor for critical components shall be not less than 1.3.
The allowable design stresses in non-critical components shall be in accordance with AS 3990 or AS 4100, or other applicable Standard where other materials have been used.
Any material used in non-critical components shall be deemed to be suitable, provided the material can be demonstrated to have the strength and serviceability required for the application.
The strength and fatigue capacity of structural elements supporting mechanical components shall be able to withstand the design’s static and dynamic loads arising from the operation of the brakes for the design service life of the winder.
Deflection limits for functionality of the braking system shall be taken into account in the design of the structural supporting elements.
NOTE The deflection limit requirements of AS 4100 maybe inappropriate for this application.
2.5 Protection of brake path
Brake paths should be protected from hazards which may affect the performance of the braking system. Hazards include oil and moisture contamination on the brake path.
2.6 Thermal capacity
The thermal capacity of the braking system shall exceed the heat generated in any mode of operation and under the most adverse load and environmental conditions.
NOTE The thermal capacity of a brake channel should exceed the heat generated in the event that all other brake channels becomes inoperable.
2.7 Braking torque limit for friction winders
The braking system shall control the retardation of the drum such that the dynamic rope tension ratio under every operating condition does not exceed 85 % of the critical head rope tension ratio.
For the purposes of calculating the critical head rope tension ratio, the coefficient of friction between the rope and the driving drum shall not exceed 0.25 unless it can be demonstrated that a higher value is achievable for all foreseeable operating conditions.
NOTE Appendix B gives sample calculations for rope slip.AS 4730.2 pdf download.