ASME HST-6 pdf download Performance Standard for Air Wire Rope Hoists
SECTION 6-1.1: GENERAL
Allequipmentselected in accordance with thisStandardis designed to perform satisfactorily when installed,inspected,tested,operated, and maintained in accordance with ASME B30.16, Chapters 16-2through 16-4, and used within the ratedload and hoist duty service classification.All equipment shall provide speeds,lifts, and headroom in accordance with themanufacturer’s specifications or specifications agreed upon by the manufacturer and user.
SECTION 6-1.2: HOIST DUTY SERVICE CLASSIFICATION
6-1.2.1 General Considerations
Service conditions have an important influence on the performance of wearing parts of a hoist, such as gears, bearings,rope, sheaves,brake linings, load and lift limit devices, wheels, and pneumatic components.Careful consideration of thehoist duty service classifications described in this Section will enable the user to evaluate the application and obtain ahoist designed for optimum performance and minimum maintenance.If doubt exists regarding hoist selection, the hoistsupplier should be consulted.Many factors enter into the selection of the proper hoist to perform a given function.Hoisting equipment consists of both mechanical and pneumatic components, and both must be considered whenanalyzing the service the hoist must perform.
The factors that influence the performance of any hoist include the following:
(a) Load Distribution.Loaddistribution isthe actualdistribution or proportion of fulland partial loads to be handled bythe equipment, including lifting devices, and has an important effect on the life of power transmission components.Forexample, ball bearing life varies according to the cube of the load.A 2-ton(1814.4-kg) hoist operated at a mean effectiveload of 1 ton (907.2 kg) will have a ball bearing life of 8 times that of the same hoist used steadily at its rated load.(b) 0perational Time. Operational time is the total running time of the hoist per hour or per work period.
(c) Repetitive Long Lowering 0perations. Such operations generate heat in control braking means.
(d Environmental Conditions. Examples include high or low ambient temperatures, dust, moisture, and corrosivefumes.
6-1.2.2 Hazardous Locations
When hoists are used in hazardous locations as defined byNFPA70 or other special codes, modifications or additionalprecautions notcovered by thisStandard maybe required. In these locations,only hoistsdesigned in a manner suitable forthe conditions encountered shall be used. Nonmandatory Appendix B provides guidance for both the manufacturer andend user to assist in configuring a hoist to make it suitable for use in a potentially explosive environment.
6-1.2.3 Duty Classification
While all the factors listed in para.6-1.2.1 must be considered in selecting the proper class of hoist, most industrialapplications can be generalized according to the percentage ofratedload normally handled and the runningtime.ListedinTable 6-1.2.3-1 are the two duty classes that have been established for air wire rope hoists.The majority of hoist applica-tions fall into the A4 category.
SECTION 6-1.3: SPECIFICATIONS OF LIFT,HEADROOM,AND REACH6-1.3.1 Lift
Lift should be specified for the application.
Headroom should be specified if important to the application.
Reach should be specified if important to the application.
SECTION 6-1.4: SPEEDS — HOIST AND TROLLEY
Hoisting equipmentis available over a wide range ofhoistand trolley speeds. Table 6-1.4-1 lists typical speed ranges.
NOTE: Table 6-1.4-1 is to be used as a guide only and is not intended to restricteither the manufacturer or the buyer from offering or specifyingspeeds outside the ranges shown; norshoulditbe inferredthatspeeds above orbelowthe ranges shownare notcompatible with the required class of hoist.
SECTION 6-1.5: TROLLEYS
Hoisttrolleysareavailableinplain,hand-chain-operated,andmotor-driventypes. Selectionofeachtypedependsupon the application.
When a trolley is required for use with a hoist, the type and size ofsupport beam shall be specified to ensure that the trolley is suitable for the minimum radius and the contour of the beam.
6-1.5.1 Plain-Type Trolleys Aplain-type trolleyis recommendedwheretrolleymotionis infrequentorrelativelyshort. Due to the force requiredto manuallyoperate this type oftrolley, itis also recommendedthatthe use ofplaintrolleys be limitedto amaximumloadof 3 tons (2 727 kg), with the elevation of the beam not more than 20 ft (6 m) above the operator’s floor level.