FEDERATION EUROPEENNE DE LA MANUTENTION FEM Section IX SERIES LIFTING EQUIPMENT 9.512 Rules for the Design of Storage and Retrieval Machines 07.1997 (E) Mechanisms

	Listof Contents	Seite
1	Object and scope	2
2	Terms and definitions------------------	---- 2
3	Classification of mechanisms according to operating conditions	2
3.1	Class of operating time	2
3.2	Load spectrum	3
3.3	Classification of mechanisms	5
4	Classification of hoist mechanisms	6
5	Travel mechanisms	7
5.1	Load spectrum considering the payload influence	7
5.2	Load spectrum considering the travel motion	7
5.3	Classification of travel mechanisms	8
6	Life under full load	9
Quoted	FEM-Documents	10
Modific	ations	10

Copyright by FEM Section IX

Continued on pages 2 t01 0 Federation Europeenne de la Manutention (Section IX) Available in German (D), English (E), French (F) Sources of supply see back page

Page 2 FEM 9.512

1 Object and scope

These rules deal with the proper interpretation of safety relevant mechanisms in storage and retrieval machines. To determine a guaranteed theoretical life expectancy for travel and hoist drive units, the mechanisms shall be classified in appropriate groups.

2 Terms and definitions

Load lifted

The load lifted comprises the dead load and the payor partial load.

Dead load

The dead load comprises the total mass (kg) of the lifting carriage and of its accessories, operator, resistance of the lifting carriage to motion and proportionate weight of the load carrying means (ropes, chains, etc.).

Payload

The pay load comprises the maximum mass (kg) of the goods to be handled, load make-up accessory (e.g. pallet), packaging material and load safeguarding material (e.g. shrinking foil, etc.).

Dead mass (kg) of the storage and retrieval machines

Mass (kg) of a storage and retrieval machine without payload or partial load.

3 Classification of mechanisms according to operating conditions

The decisive operating conditions for storage and retrieval machines are:

• class of operating time and

  • load spectrum

3.1 Class of operating time

The class of operating time indicates the average period per day during which a mechanism is in operation (see table 1). The total operating time in hours is determined by the ratio of the annual operating time to 250 working days per year. A mechanism is considered to be in operation when it is in motion.

The higher classes of operating time apply only in such cases where a mechanism is operated more than one shift per day.

Class of operating time	Average operat- ing time per day in hours	Calculated total operating time in hours
V1	:'5:2	3.200
V2	:'5:4	6.300
V3	:'5:8	12.500
V4	:'5:16	25.000
V5	> 16	50.000

Table 1: Class of operating time

FEM 9.512 Page 3

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3.2 Load spectrum

The load spectrum indicates to what extent a mechanism or part thereof is subject to maximum stress or whether it is subject to smaller loads only.

For an exact classification into groups, the cubic mean value k referred to the load to be lifted is required. Under the assumption that the life of the mechanism is inversely proportional to the third power of the load it is calculated by using the following formula:

In the formula:

~. = Effect of payor partial load

• I Effect of permissible load

Effect of deadload

Y = Effect of permissible load

t. = Operating time under payor partial load

• I Total operating time

• t = Operating time under deadload only t. Total operating time

Following FEM 9.511, four load spectra are distinguished. For storage and retrieval machines the load spectra listed in table 2 are used, which are determined by the definitions given and by the ranges covered by the cubic mean values k.

Load spectrum	Definitions	Cubic meanvalue
L2 (medium)	Mechanisms or parts thereof, rather often subject to maximum loads, but usually to small loads	0,50 <k ~ 0,63
L3 (heavy)	Mechanisms or parts thereof, often subject to maximum loads and usually to medium loads	0,63 <k ~ 0,80
L4 (very heavy)	Mechanisms or parts thereof, usually subject to almost maxi- mum loads	0,80 <k ~ 1,00

Table 2: Load spectrum

The limit values listed in table 2 for the cubic mean values of k can be calculated from the following ideal load spectra:

Page 4 FEM 9.512

Load spectrum L 2 (medium)

Relation of deadload to payload y = 0,2

1/6 of the operating time under maximum load = deadload + 1/1 payload t1 = 0,167 ~1 = (1 - y) = 0,8 1/6 of the operating time under deadload + 2/3 payload tz = 0,167 ~z = 2/3 (1 - y) = 0,533 1/6 of the operating time under deadload + 1/3 payload t3 =0,167 ~3 = 1/3 (1 - y) = 0,267 1/2 of the operating time under deadload only t a = 0,5 y = 0,20 The result is:

k z = 3(0,80 + 0,20)3·0,167 + (0,533 + 0,20)3. 0,167 + (0,267 + 0,20)3. 0,167 + 0,20³ .0,5 ~ 0,63

Load spectrum L 3 (heavy) Relation of deadload to permissible load y = 0,4

50 % of the operating time under maximum load = deadload + 1/1 payload t 1 = 0,5 ~1 = 1 - y = 0,60 50 % of the operating time under deadload only ta = 0,5 y=0,40 The result is:

k3 = ~(O,60 + 0,40)3.0,5 + 0,40³ .0,5 ~ 0,80

Load spectrum L 4 (very heavy) Relation of deadload to permissible load y = 0,8

90 % of the operating time under maximum load = deadload + 1/1 payload

t1 = 0,9 ~1 = 1 - Y= 0,20 10 % of the operating time under deadload only t a = 0,1 y = 0,80

The result is:

FEM 9.512 Page 5
o 50 100
1,0
o 90100
Figure 1

3.3 Classification of mechanisms

By applying the classes of operating times and the load spectra, the mechanisms are classed into 3 groups: 3 m, 4 m and 5 m, as shown in table 3.

			Class	ofoperatin	g time
Load spectrum	Cubic mean	V1	I V2	I V3	T V4	I V5
	value	~2	Mean operat ~4	ing time per ~8	day in hour ~16	s >16
L2	0,50 <k ~ 0,63			3m	4m	5m
L3	0,63 <k ~ 0,80		3m	4m	5m
L4	0,80 <k ~ 1,00	3m	4m	5m

Table 3: Classification of mechanisms into groups

The result of the classification of mechanisms into groups according to table 3 is that the same life, expressed in years, may be expected for these mechanisms under all load spectra and mean operating times per day.

Transition between the individual fields of the table is possible using the following basic rules:

• horizontal transition: for identical load spectra, the next highest mechanism group is selected by doubling the mean daily operating time.

• vertical transition: if a mechanism group is not available, a lower load spectra shall be achieved e.g. by reducing the rated load or operating time class.

• diagonal transition: for an identical mechanism group, the transition to a higher load spectrum implies a reduction of the class of operating time. For example, by transition to the next lowest load spectrum, the doubling of the mean operating time per day by maintaining the same group of mechanisms can be achieved (progression 1,25 since 1,25³ ~ 2).

NOTE: The load spectrum can be changed by the actual load being lower than the maximum load possible or by reducing the amount of time needed with maximum load.

Page 6 FEM 9.512

4 Classification of hoist mechanisms

For hoist mechanisms the cubic mean value kH is calculted by using the following formula:

where:

~ _ Effect of payor partial load Hi - Effect of dead load + payload

Effect of deadload Y -----------H - Effect of dead load + payload

t . = Operating time under payor partial load HI Total operating time

t = Operating time under deadload only Hl1 Total operating time

Example for the classification into groups of a hoist mechanism

A hoist mechanism, payload 1000 kg, for a storage and retrieval machine equipped with a telescopie load fork, is operated four hours daily without any interruption according to class of operating time V 2, table 1. For a deadload of 1600 kg (weight of the lifting carriage and of the telescopic fork) the following load spectrum applies:

65 %ofthe operating time with 1600 kg deadload and 1000 kg payload	tH1 ~H1	=0,65 =1000/2600=0,385
35 % Ofthe operating time with 1600 kg deadload	tH6	=0,35
(combined working cycle)	YH	=1600/2600=0,615

The cubic mean value would be

According to the k range in table 2 and 3 a load spectrum 4 (very heavy) applies. With the class of operating time V 2 the table 3 shows group of mechanisms 4 m.

For a payload of 1000 kg the hoist mechanism used shall at least satisfy the conditions of the group of mechanisms 4m•