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Washington Administrative Code (Last Updated: November 23, 2016) |
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Title 296. Labor and Industries, Department of |
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Chapter 296-96. Safety regulations and fees for all elevators, dumbwaiters, escalators and other conveyances. |
Section 296-96-23256. What requirements apply to indirect-drive machines?
Latest version.
- (1) Indirect-drive machines, utilizing V belts, tooth drive belts, or chain drives, must have at least three belts or chains operating together in parallel as a set. Belt and chain drive sets must be pre-loaded and matched for length.(2) Belt set selection must be based upon the manufacturer's rated breaking strength and a safety factor of 10. Chain and sprocket set selection must be based upon the recommendations in the supplementary information section of ASME/ANSI B 29.1, using a service factor of 2.0. Offset links in a chain are permitted. Chain drives and belt drives must be guarded to protect against accidental contact and to prevent foreign objects from interfering with drives.Sprockets in a chain drive set and also in a driven set must be assembled into a common hub, with teeth cut in line after assembly to assure equal load distribution on all chains. Tooth sheaves for a belt drive must be constructed in a manner to assure equal load distribution on each belt in the set.Load determination for both the belt and chain sets must be based on the maximum static loading on the elevator car (full load on the car and the car at rest at a position in the hoistway which creates the greatest load, including either the car or counterweight resting on its buffer).(3) Each belt or chain in a set must be continuously monitored by a broken belt or chain device of the manually reset type which must function to automatically interrupt power to the machine and apply the brake in the event any belt or chain in the set breaks or becomes excessively slack. The driving machine brake must be located on the traction sheave or winding drum assembly side of the driving machine so as to be fully effective in the event the entire belt set or chain set should break.(4) If one belt or chain of a set is worn, stretched, or damaged so as to require replacement, the entire set must be replaced. Sprockets and toothed sheaves must also be inspected on such occasion and be replaced if noticeably worn.