How to Select an Electric Chain Hoist

Questions to consider for choosing a suitable electric chain hoist

Required capacity
Lifting height
Ambient conditions:
- Normal Humidity
- Dust
- Dirt
- Particular temperatures °C
- Increased rel. humidity %
- Other
How long is the hoist in operation:
- Load cycles per hour
- Hours per day
- Days per week
- Distance covered per lifting cycle
Unusual operating conditions that could be important for the choice and function of the electric chain hoist
Type of load:
- Permanent
- Changing
- Shocks
- Vibration
- Static
Trolley drive
- Motor
- Manual
Operating voltage:
- 400 V
- 230 V
- 3 - phase a.c.
- 1-phase a.c.
Power frequency:
- 50 Hz
- 60 Hz
Protection
- IP 54
- Other

General information about electric chain hoists

Apart from the usual criterion such as lifting capacity, lifting speed and dimensions also consider following: 1. Choosing a motor according to FEM 9.682 In addition to the torque the decisive criterion for rating an electric motor is the heat it generates. Here we differentiate between two operational modes. 1.1 Intermittent duty In this case the motor is designed for a series of equal cycles consisting of duty periods with constant load and rest periods. The heat generation depends on the relative duty cycle, that is, the relationship between operating period under load, total operating time and the number of starts/hour.

Duty rating ED = (Operating period / Operating period + rest periods) %

The number of cycles that can be made under full load is calculated as follows:

S ≈ 0,3 x ED x V / H

S = Cycles per hour
ED = Duty rating in %
V = Lifting speed in m/min.
H = Average lifting height in m

A cycle consists of a motion of lifting, lowering and the rest periods. One must ensure that the lifting height does not exceed the value permitted by the percentage duty cycle referred to a cycle period of 10 minutes.

H ≤ ED x V / 20

and that simultaneously the permissible number of starts is not exceeded. It is generally accepted that a cycle consists of 6 starts.

1.2 Short time duty

Where special duty conditions exist (e.g. long hook path) the operating period must be of such length that the admissible temperature limit of the motor is not exceeded. For such cases intermittent duty must be replaced by short time duty. That is, the motor may be operated for up to 10 starts over a certain period (usually 15 min.). Thereafter the motor must cool down to room temperature.

1.3 Calculation example intermittant duty:

Electric hoist : CPM 5-8
Lifting speed : 8 m/min.
Lifting height : 2,8 m
Duty rating ED : 50 % c/h : 180

Number of cycles per hour S = 0,3 x 50 x 8 / 2,8 = 42,8 Max. lifting height H = 2,8 ≤50 x 8 / 20 = 20 m Number of starts N = (25 cycles / hour) x (6 starts / cycle) = 150

2. Classification of hoisting equipment according to FEM 9.511

To choose an optimal hoist the lifting capacity and also the classification group must be known. The classification group indicates the theoretical operating time of the mechanical components under full load:

Classification group	1Bm	1Am	2m
Operating time in h	400	800	1600

If the hoist is operated as classified an actual operating time of around 10 years can be expected. After this period a general overhaul is necessary. To define the classification group following values must be determined:

2.1 Average operating time per day

The average operating time can be estimated or calculated as follows:

Operating time/day = (2 x average hook path x cycles /hour x operating time/day / 60 x lifting speed

Electric hoists provided with counters for operating hours and number of starts simplifiy the classification (see CPM page 54)

2.2 Load spectrum

The load spectrum indicates to what extent a hoist or part thereof is subject to maximal stress or whether it is subject to smaller loads only. It can be calculated or estimated according to the diagrams on the right:

1 light	2 medium	3 heavy	4 very heavy

Hoists or parts thereof usually subject to very small loads and in exceptional cases only to maximum loads.	Hoists or parts thereof usually subject to small loads but rather often to maximum loads.	Hoists or parts thereof usually subject to medium loads but frequently to maximum loads.	Hoists or parts thereof usually subject to maximum or almost maximum loads.

2.3 Classification

The classification group is defined by operating hours and load spectrum:

Load Spectrum	Aver. op hours per working day
1 light	up to	2	2.4	4-8
2 medium	up to	1	1-2	2-4
3 heavy	up to	0.5	0.5-1	1-2
4 very heavy	up to	0.25	0.25-0.5	0.5-1
Classification group acc. to FED/DIN 15020		1Bm	1Am	2m

Degrees of protection according to EN 60529

Depending on the operating and environmental conditions the damaging effect of water, foreign particles and dust and the contact with live or moving parts inside a motor is to be prevented by choosing a suitable protection. The marking used to indicate the degree of protection consists of the letters IP followed by two characteristic numerals. The marking applies to the unit as it is supplied and the defined or usual location of the unit. The protection can change if the unit is located or fitted differently.

IP	1st digit for protection against ingress of solid foriegn particles	2nd digit for protection against ingress of liquid
IP	0 to 6	0 to 8

Motor cooled internally

Protection	1st digit contact protection	ingress of solid foreign particles	2nd digit ingress of liquid
IP 00	no protection	no protection	no protection
IP 02			drops of water when tilted up to 15° from vertical
IP 11	large surface contact	foreign bodies over 50 mm Ø	vertical water drops drops of water when tilted up to 15° from vertical spray water when tilted up to 60° from vertical
IP 12
IP 13
IP 21	contact with fingers	foreign bodies over 12 mm Ø	vertical water drops drops of water when tilted up to 15° from vertical spray water when tilted up to 60° from vertical
IP 22
IP 23