| The following chart is provided to give the reader an idea of the relative significance of the duty cycle ratings for the various electric hoists depicted in this web. The duty cycle determination for a particular application involves obtaining a significant amount of additional information and expertly applying it to the intended use. Please consult our application experts before making any duty cycle decisions. This table is given for reference only. Do not rely upon it for your application. | |||||
| Hoist Duty Class | Typical Areas of Application | Operational Time Ratings at 65% Mean Load Factor | |||
|---|---|---|---|---|---|
| Uniformly Distributed Work Periods | Infrequent Work Periods | ||||
| Max On Time Min/Hour | Max No. Starts/hr. | Max On Time from Cold Start | Max Number Starts | ||
| H1 | Powerhouse and Utilities, infrequent handling, Hoists used primarily to install and service heavy equipment, loads frequently approach capacity and hoist idle for long periods between use. | 7.5 minutes (12.5%) | 75 | 15 minutes | 100 |
| H2 | Light machine shop fabricating, service and maintenance; loads and utilization randomly distributed; rated loads infrequently handled. Total running time not over 12.5% of the work period. | 7.5 minutes (12.5%) | 75 | 15 minutes | 100 |
| H3 | General machine shop fabricating, assembly, storage, and warehousing; loads and utilization randomly distributed. Total running time not over 25% of work period. | 15 minutes (25%) | 150 | 30 minutes | 200 |
| H4 | High volume handling of heavy loads, frequently near rated load in steel warehousing, machine and fabricating shops, mills, and foundries, with total running time not over 50% of the work period. | 30 minutes (50%) | 300 | 30 minutes | 300 |
| Manual or automatic cycling operations of lighter loads with rated loads infrequently handled such as in heat treating or plating operations, with total running time frequently 50% of the work period. | |||||
| H5 | Bulk handling of material in combination with buckets, magnets, or other heavy attachments. Equipment often cab operated. Duty cycles approaching continuous operation are frequently necessary. User must specify exact details of operation, including weight of attachments. | 60 minutes (100%) | 600 | Not Applicable [Note (1)] | Not Applicable [Note (2)] |
| NOTE: (1) Not applicable since there are no infrequent work periods in Class H5 service. | |||||
Selection is based on:
- Load Spectrum
- Average operating time per day
- Daily working time
- Starting frequency
- The basis for calculations according to FEM standards is a 10 years lifetime for hoists
- The FEM group is determined by the daily operating time and the load spectrum
- The selection of the correct FEM group enables us to find the most suitable size of hoist for different applications
The FEM group also specifies the ED% and the starting frequency of motors
Selection of suitable FEM group
Instruction:
- Select the load spectrum type
- Follow the load spectrum to the right, across the table and compare your average operating time per day value (t) to the limits in the table.
- Stop where your calculated value (t) is between the limits.
- Move down that same column to get your hoist group, duty factor, and maximum starts per hour.
Example
- Information
- Load Q = 3000 kg
- Hoisting speed v = 8m/min (2 ropes)
- Average hoisting height H = 3m
- Number of work cycles N = 16/h
- Daily working time T = 8 h
- Load spectrum: Heavy
- Calculation
- Average operating time per day
- t = (4 x H x N x T/ V x 60) hours (h) = (4 x 3 x 16 x 8/ 8 x 60) = 3.2 h which is < 4 h
- Number of starts per hour when two extra start-ups are estimated for each normal start
- F = 4 x 16 x 3 = 192/h which is < 300
- Solution
- According to table, hoist group FEM 3m. Select a hoist with this rating