ASME HST-1:2017 pdf free download

ASME HST-1:2017 pdf free download.Performance Standard for Electric Chain Hoists.
All equipment selected in accordance with this Standard is designed to perform satisfactorily when used in accordance with Chapters 16-2 through 16-4 of ASME 1130.16 and used within the rated load and hoist duty service dass ltkatlon. All equipment shall provide speeds, lifts, and headroom in accordance with the manufacturer’s speciflcations or to specifIcations agreed upon by the manufacturer and the user.
SECTION 1-1.2: HOIST DUTY SERVICE CLASSIFICATION
Service conditions have an Important Influence on the performance of the wearing parts ola hoist, such as gears, bearings, load chain, sprockets, electrical equipment, brake linings, load and lift limiting devices, and wheels. Careful consideration of the hoist duty service dassifications described in this Section will enable the user to evaluate the application, and to obtain a hoist designed for optimum performance and minimum maintenance. If doubt exists regarding hoist selection, the hoist supplier 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 electrical components and both must be considered when analyzing the service the hoist must perform.
The factors that influence the mechanical and electrical performance of any hoist include the following:
(a) Load Distribution. The actual distribution or proportion of full and partial loads to be handled by the equipment, including lilting devices, has an important effect on the life of power transmission components. For example, ball-bearing life varies according to the cube of the load. A 2-ton (1 814.4-kg) hoist operated at a mean effective load of I ton (907.2 kg) will have a ball-bearing life eight times that of the same hoist used steadily at Its rated load.
(b) Operational Time. Operational time is the total running time of the hoist per hour or per work period.
(c) Work Distribution. This is determined by whether the operational time is uniformly distributed over the work period or concentrated in a short time span. Work distribution generally does not appreciably affect mechanical wear, but does materiaLly ailed the electrical components such as motors, brakes, and controls. For example, a hoist motor designed to operate 15 min outof each hour of an 8-hr shift cannot handle 2 hr ofsteady run and 6 hr of idle time even though either condi-tion only requires 2 hr of operational time per 8-hr shift.(dy Number of Starts and Stops. This directly affects allelectromechanical devices, such as motors. contactors,brakes. and solenoids.
(e) Repetitive Long Lowering Operations. Such opera-tions generate heat in control braking means.
Environmental Conditions. Hoist equipment isdesigned to operate in ambient temperatures between0°F (-18C) and 104F(40°C) and in atmospheres reason-ably free from dust, moisture, and corrosive fumes unlessotherwise specified.
(g) Hazardous Locations.If hoists are used in hazardouslocations as defined by NFPA 70 or other special codes,modifications or additional precautions not covered by this Standard may be required. ln these locations,onlyhoists designed in a manner suitable for the condition sencountered shall be used.