ASME HST-4-2021 pdf – Performance Standard for Overhead Electric Wire Rope Hoists
ASME HST-4-2021 pdf – Performance Standard for Overhead Electric Wire Rope Hoists.
The hand chain shall be guarded to prevent its disengagement from the hand chain wheel. The hand chain shall withstand, without permanent deformation, a force of three times the pull required to traverse the trolley with rated load.
4-1.6.3 Motor Operated
A motor-operated trolley is recommended where the operating frequency, distance of travel, rated load, beam elevation, or type of load being handled exceeds recommendations for the use of plain or hand-chain-operated trolleys. The design of motor-operated trolleys shall be based on intermittent operation on a straight beam unless otherwise specified. Where trolley travel involves a curved beam, beam switches, exceptionally long runs, or near continuous operation, a special design may be required. Full particulars should be provided with the inquiry.
A cushioned start or multispeed drive is recommended for trolley speeds above 100 ft/mm (30 m/min) or for use on beams with curved sections. Brakes, when specified, should be actuated by mechanical or electricaL means and shall have the following characteristics:
(a) Brakes shall have sufficient capacity to stop the trolley within a distance in feet (meters) equal to 10% of the rated speed in feet (meters) per minute when traveling at rated speed with rated load.
(b) Brakes shall have heat dissipation capability for the frequency of operation defined by the user.
(c) Brakes shall have provision for adjustment where necessary to compensate for wear.
4-1.6.4 TroLLey WheeLs
When a trolley is required for use with a hoist, the type and size of support beam must be specified to ensure the trolley wheel contour is suitable for the contour of the beam.
SECTION 4-3.1: GENERAL
All furnished electrical equipment shall conform to the applicable sections of the latest edition ofANSI/NFPA 70. The user shall specify the voltage, frequency, and phase of the power supply. The supply voltage shall be maintained within ±10% of the rated motor voltage at the hoist with motor operating at rated load.
4-31.1 Hazardous Locations
When hoists are used in hazardous locations as defined by ANSI/NFPA 70 or other special codes, modifications or additional safety precautions not covered by this Standard may be required. Only hoists designed for the conditions encountered shall be used in these locations.
4-3.1.2 Fungus Protection
In tropical areas or other warm and humid atmospheres, fungus growth may occur on unprotected organic materials or on accumulations of dust. There are materials and procedures that will minimize these effects. Refer to the hoist manufactu re r.
SECTION 4-3.2: MOTORS
(a) Motors shall be reversible, with torque characteristics suitable for hoist or trolley service, and capable of operation at rated loads and speeds in accordance with the specified service class.
(b) Temperature rise of motors shall be in accordance with the latest NEMA MGi Motor Standard for the class of insulation and enclosure used. The hoist manufacturer will assume 104°F (40°C) ambient temperature unless otherwise specified by the user.
(c) All AC motors at rated frequency and all DC motors shall be capable of operation within ±10% of rated motor voltage, but not necessarily at rated voltage performance.
(d) Standard rated motor voltage shall be in accordance with Table 4-3.2-1.
(e) For nominal system voltage other than shown in Table 4-3.2-1, the rated motor voltage should not be less than 95% of and should not exceed the nominal system voltage.
SECTION 4-3.3: CONTROLLERS
4-3.3.1 Types of ControL
The following types of controL are available:
(a) single-speed squirrel-cage motor with single-speed magnetic control for use on hoists and trolleys
(b) two-speed squirrel-cage motor with two-speed magnetic control for use on hoists and trolleys
(c) variable-speed wound rotor trolleys
(1) three-position, or more, magnetic control for use on hoists with mechanical load brake and on trolleys
(2) five-position magnetic electric load brake control for use on hoists without mechanical load brake
(3) five-position magnetic counter-torque control for use on hoists without mechanical load brake
(d) single-speed squirrel-cage motor with cushioned start for use on trolleys
(e) two-speed squirrel-cage motor with cushioned start for use on trolleys
Other types of hoist and trolley control are available that are beyond the scope of this Standard. Consult the hoist manufacturer.