ASME HST-4:2016 pdf free download

ASME HST-4:2016 pdf free download.Performance Standard for Overhead Electric Wire Rope Hoists.
SECTION 4-1.1 GENERAL
All equipment selected in accordance with this Standard is designed to perform satisfactorily when installed, inspected. tested, operated. and maintained in accordance with Chapters 16-1 through 16-4 of ASME 1130.16 and used within the rated load and hoist duty sernce cbssiuication. All equipment shall provide speeds, lifts, and lwadroom in accordance with the manufacturer’s specifications or to specifications agreed upon by the manufacturer and user.
SECTION 4-1.2 HOIST DUTY SERVICE CLASSIFICATION
4-1.2.1 General Considerations
Service conditions have an important influence on the performance of wearing parts of a hoist such as gears, bearings, rope, sheaves, electrical equipment, brake linings. load- and lift-limit devicus. and wheels, Caivful consideration of the hoist duty service classifications 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 perforni
The factors that influence the performance of any hoist include the lollowing:
The actual distribution or proportion of full and partial loads to be handled by the equipment, including lifting devices, has an important effect on the life of poss’er transmission components. Far ezample, ball bearing life generally varies inversely 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.
(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 affect the electrical components such as motors, brakes, and controls. For example, a hoist motor designed to operate 15 min out of each hour of an 8-hr shift cannot handle 2 hr of steady run and 6 hr of idle time even though either condition only requires 2 hr of operational time per 8-hr shift.
(d) Number of Starts and Stops. This directly affects all electromechanical devices, such as motors, contactors, brakes, and solenoids.
(e) Repetitive Long Lowering Operations. Such operations generate heat in control braking means.
(f) Environmental Conditions. Such conditions include ambient temperature and the presence of dust, moisture, corrosive fumes, etc. Hoist equipment is designed to operate in ambient temperatures between 0°F and 1049F (-18°C and 40°C) and in atmospheres reasonably free
from dust, moisture, and corrosive fumes unless otherwise specified.