ASME B30.7 pdf download

ASME B30.7 pdf download BASE- MOUNTED DRUM HOISTS
Section 7-1.1: Load Ratings and Markings7-1.1.1 Basis. Hoist ratings are dependent uponsuch factors as applied power，amount of rope woundon the drum,drum size,and structural competence ofthe various hoist components and mounting methods.
7-1.1.2 Load Ratings. Load ratings shall be themanufacturer’s recommended single rope pull in pounds(kilograms) at a specified rate of speed on a givensize drum and prescribed number of layers of rope.7-1.1.3 Markings. Hoists are to be marked withthe following identifications for each drum:
(a) load rating;
b) drum size consisting of barrel diameter，barrellength, and flange diameter;
(c) rope size(s);
(d) rope speed in feet per minute (meters per second);(e) rated power supply.
Section 7-1.2: Construction
7-1.2.1 General. Hoists shall be designed and con-structed to meet all stresses imposed on their framesand components under normal operating conditionswhen properly installed and with handling loads notexceeding the manufacturer’s load ratings. Weldingshall conform to recommended practices of ANSIAwSD14.3.
7-1.2.2 Hoist and Swinger Mechanisms(a) Drum assemblies shall be provided with powerand operational characteristics to perform all lifting,lowering,and swinging functions when operated atrated load.
(b) Where maximum rated loads are being loweredfor long distances, power controlled lowering usually isnecessary to reduce the demand on the brake. Additionalcooling provisions may be required on fluid transmis-sions or torque converters.
(c) The drum capacity shall accommodate the recom-mended rope size and length necessary to perform the specified function required for the load-handlingequipment with which the hoist is used.
(1 ) No less than two full wraps of rope shallremain on the drum with the tackle system of the load-handling equipment extended to its maximum reach.
(2) Each drum end of the rope shall be anchoredby a clamp attached to the drum, or by a socketarrangement approved by the hoist or rope manufacturer,providing for attachment of rope to the drum.
(3 ) Drum flanges shall extend a minimum of ‘l2in. (13 mm) over the top layer of rope at all times.(d) Diameter of the drum shall provide first layerrope pitch diameter of not less than the following:(1) 18 times the nominal diameter of the ropeused for service such as lifting or lowering a load(hoisting);
(2) 15 times the nominal diameter of the ropeused for service such as raising or lowering a boom(booming);
(3) 15 times the nominal diameter of the ropeused for service such as barge anchor handling;(4) 15 times the nominal diameter of the ropeused for swingers.
(e) Drums which hold items such as loads and boomssuspended for a considerable time shall be providedwith a ratchet and pawl or equivalent holding means,other than a brake，which shall be operable from theoperator’s station.
(f) All hoist and swing drives should be capable ofstarts and stops with variable acceleration and decelera-tion required in normal operation.
7-1.2.3 Brakes
(a) Each load hoist mechanism shall be equippedwith at least one brake having a torque rating not lessthan that produced by 125% of the maximum ratedline pull at the point where the brake is applied. Themaximum rated line pull at each rope layer on thedrum shall be considered in determining this rating.(b) When power operated brakes having no continu-ous mechanical linkage between the actuating and brak-ing means are used for controlling loads,an automatic