This comparison of hoist duty service classifications as described in US and European wire rope hoist specifications was developed by member companies of the Hoist Manufacturers Institute (HMI), a US trade association of manufacturers of overhead handling hoists, to offer information to those considering purchase and use of overhead handling hoists.

Because of the general nature of US hoist distribution channels, wherein hoist manufacturers may often not be aware of exact hoist applications, and further the nature of the liability laws, it has customarily been the practice of US hoist manufacturers to design and build products with long, although unspecified, service lives. This may be contrasted with the practices of many European manufacturers who build and provide products for specific applications and state mandated removal from service dates for overhaul or replacement.

This study excludes electric chain hoists due to the lack of any US specifications that indicate electric chain hoist life, for example bearing life.

Comparison

This comparison examines the following listed US standards and the rules published by the Fédération Européenne de la Manutention (FEM) and provides a comparison of these wire rope standards:

From the United States:

ANSI/ASME HST-4-1996 Performance standard for electric wire rope hoists

From Europe:

FEM 9.511-1986 (E) Rules for the classification of mechanisms

FEM 9.683-1995 (E) Selection of lifting and travel motors

FEM 9.755-1993 (E) Measures for achieving safe working periods for motorised serial hoist units.

To permit evaluation of a hoist’s application as well as compare the US and European specifications, several hoist application parameters must be considered. These are the average operating time per day, load spectrum, starts per hour, operating period and equipment life. Each of these terms is briefly defined as follows and discussed in detail in the paragraphs that follow.

• Average operating time per day – the average hoist operating time for each day.

• Load spectrum – the load magnitude, as a percentage of hoist rated capacity, expressed over the duration of hoist operation.

• Starts per hour – the number of hoist motor starts per hour.

• Operating periods – the hoist operating time in minutes per hour as expressed over a work period.

• Equipment life – the projected hoist life based on a number of given factors including those previously defined.

Average operating time per day

The rules of FEM 9.755 specify the hoist equipment working life to be 10 years. A working year is defined as 250 days. The HST-4 standard does not stipulate the equipment working life. However, the average operating time in hours per day may be determined from the bearing life specified for each HST-4 hoist duty service classification. This is illustrated in Table 2, considering the equipment working life to be 10 years of 250 days per year. The average operation time developed from bearing life is similar to a portion of the range specified in the rules of FEM 9.511.

Load Spectrum

The HST-4 standard publishes a written description of a load spectrum utilised to define a mean effective load factor of 0.65. It defines the load to be ‘the total imposed weight on the load block or load hook including lifting devices’. Although the text does not specifically indicate whether or not the unloaded portion of the spectrum considers the dead load of slings or hook-on lifting devices, the examples in Appendix A of this standard would support a conclusion that the spectrum does not consider them during the no load operation. From the written description of the standard and several assumptions, the model illustrated in the graph HST-4 is one representation of this load spectrum. It is divided into one duration of 100% rated load, a second duration of randomly distributed loads and a third duration of no load. The standard does not define when the load carrying means (hook, lower block and wire rope) must be considered as a part of the dead load. However, paragraph 2.3.2.c of this standard recommends using the detailed application analysis if a below the hook lifting device is attached to the load hook. This is also addressed in the examples in Appendix A of this standard.

The rules of FEM 9.511 identify four load spectra, defining their load magnitudes and durations with graphic models. Load spectrum number two has a mean effective load factor of 0.63 which is similar to that of HST-4 which is 0.65. It is divided into three durations of dead load (slings and hook-on lifting devices) and various useful loads and a fourth duration of dead load only. This load spectrum is illustrated in the graph FEM 9.511. The load carrying means (hook, lower block and wire rope) is not considered a part of the dead load if it is less than or equal to 5% of the safe working load (useful load plus dead load).

As can be seen from the graphs, the load spectrum assumptions leading to the mean effective load factor differ between the two specifications. Many load spectra, however, can be developed which will provide the same magnitude for the mean effective load factor.

The hoist duty service classifications based on similar average operating time and load spectrum are combined at the top of Table 1 for comparison. Although there are more time classifications in the FEM 9.511 rules than in the HST-4 standard, there is some similarity between the specifications. FEM 9.511 indicates that the higher classes of operating time apply only to applications where the equipment is operated during more than one shift a day. This recognition is not made in HST-4.

Starts per hour

The rules of FEM 9.683 paragraph 5.8.2.2 define the number of starts per hour for hoist motors. These are illustrated in the second tier of Table 1, with those specified in HST-4 based upon the hoist duty service classification. The comparison indicates that the FEM requirements for classes corresponding to HST-4 classifications H1 through H3 are greater than that required by the HST-4 standard but are less than required by HST-4 for the classes corresponding to HST-4 classifications H4 and H5.

Operation periods

For each hoist duty service classification, the HST-4 standard specifies a maximum “on” time in minutes per hour for uniformly distributed work periods. These time periods result from distributing the average operating time per day, determined from bearing life for the hoist duty service classifications H2 to H5, over an eight hour period.

The rules of FEM 9.683 define the minimum “on” time based on a maximum duty cycle period of 10 minutes and a cyclic duration factor for each hoist duty service classification. Total “on” time in minutes per hour is tabulated from this data.

This information is tabulated in the third tier of Table 1. The comparison indicates that the FEM requirements for classes corresponding to HST-4 classifications H1 through H3 are greater than those required by the HST-4 standard but are less than those required by HST-4 for the classes corresponding to HST-4 classifications H4 and H5. Larger FEM cyclic duration factors can be agreed between the customer and the manufacturer, thus yielding greater “on” times per hour.

Both specifications identify operation for infrequent work periods after the equipment has cooled to ambient temperature. These operating periods are tabulated in the fourth tier of Table 1, relative to hoist duty service classification. The comparison indicates that the FEM requirements for the classes corresponding to HST-4 classification H1 and H3 are less than that required by the HST-4 standard. The HST-4 standard identifies continuous operation for hoist duty service classification H5 under uniformly distributed work periods (see tier three, Table 1) and therefore has no infrequent work period.

Equipment life

The FEM rules use range R10 of the Renard series for capacities, lifts, lift speeds and total operating time. FEM 9.511 Table 2 defines the total operating time corresponding to the average operating time per day. FEM 9.755 defines the total operating time as 10 years.

The bearing life specified in the HST-4 standard defines the total operating time. Being consistent with the calculation of the average operating time per day above, the total life is considered to be 10 years.

This information is tabulated in the fifth tier of Table 1. The comparison indicates that the FEM requirements for classes corresponding to HST-4 classifications H1 through H5 are less than those required by the HST-4 standard.

Conclusion

Table 1 suggests that the requirements of ANSI/ASME HST-4 hoist duty classifications H4 and H5 are greater than or equal to those of the FEM Rules for a mean effective load of 0.65. Therefore equipment meeting these classifications could be applied to applications of FEM classification of mechanisms 2m and 3m. If a class H3 product was capable of 180 starts per hour in lieu of the 150 starts per hour specified in the HST-4 standard, it could be applied to applications of FEM classification of mechanisms 1Am. However, the equipment should, in addition, meet the provisions of the balance of the FEM rules such as the design of rope reeving components and selection of travel motors.