Guidelines for VNA (Very Narrow Aisle) Forklift and Racking System.pdf

Guidelines for planning and setting up very narrow aisle warehouses

Table of contents

Floor................................................................................................. 6 Specifications for the floor....................................................................7 Height differences and evenness tolerances.......................................8 Racking.......................................................................................... 14 Assembly tolerances for racks and permissible deformations..........16 Safety distances in the rack................................................................18 Guide systems............................................................................... 19 Mechanical guide: rail guidance.........................................................20 a.) Design and assembly of guide rails...................................... 20 b.) Overview of rail types.......................................................... 22 Inductive wire guidance......................................................................24 a.) Laying an inductive guide wire............................................ 24 b.) Entering and exiting the aisle/changing aisles.................... 26 c.) Frequency generator............................................................. 27 Driver assistance system.............................................................. 28 1. Systems for determining vehicle position......................................29 a.) Magnets...................................................................................30 b.) Reflected light sensors............................................................31 c.) Bar code...................................................................................32 d.) RFID..........................................................................................32 2. Safety functions in the very narrow aisle......................................33 a.) End of aisle protection.......................................................... 33 b.) Height-dependent cut-off.......................................................34 c.) VNA navigation........................................................................35 Personnel protection systems...................................................... 37 Legal regulations.................................................................................38 Stationary protection...........................................................................38 Mobile protection................................................................................39 Standards...................................................................................... 41

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Guidelines for planning and setting up. very narrow aisle warehouses Narrow aisle warehouses have a particularly high space utilisation rate through very low spatial requirements and high lift heights. These aspects require special attention in planning and implementation. These guidelines provide you with a tool which should help you in building the most economical, safe, and functional narrow aisle warehouse. They also utilize your floor space and spatial resources efficiently and ensure optimum implementation for truck, racking, and flooring interfaces in your premises. Our recommendations and directives in the following should prevent bad investment as well as deficiencies in construction, leading to professional solutions.

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The floor

High rack storage areas where man-down narrow aisle trucks are used are technically advanced systems today. The use of highlevel order pickers, racking trucks and order picking trucks in such warehouses not only requires technically highly developed industrial trucks, but also floors of above average quality. They must be capable of carrying loads, level, and horizontal, and meet the strictest tolerances for travel paths of the VDMA directive (the tolerances according to DIN 18202 apply for all remaining surfaces).

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Only compliance with the VDMA directive requirements can guarantee the full performance of the trucks and their associated productivity. Testing the floor surface for evenness should be done directly after installing the floor, and before beginning any subsequent work. Proof of compliance with the tolerances is provided by the floor installer or a neutral surveyor office (also see: www.VDMA.org/Branchen/Logistiksysteme).

Linde VNA Directives // Floors

Specifications for the floor The following listed values and tolerance ranges are essential for permissible driving speeds, diagonal driving heights, a smooth ride, and positioning accuracy for the trucks used. Therefore, pay special attention to the “floor tolerances”. To avoid possible misunderstandings, we recommend you to make these directives part of your agreement with the floor installer and racking manufacturer. Sub-flooring: • The supporting subsoil is designed according to DIN EN 1045 part 1 and two using a concrete quality of at least B25 and DIN 18202. Use-surface (top layer): • The load group II (middle) DIN EN 18560, part 7, table 1 (resistant against oils and grease) requires an approx. 10 –30 mm thick industrial flooring. • The surface must be anti-skid (approx. µ 0.5), anti-slip, free of fluids, dirt, and oil films and must not exhibit plastic deformation under load in order to achieve the braking distances according to ISO 6292. The resistance to earth RE must be a maximum of 10^6 ohm (per DIN EN 1081).

Sub-concrete

Iron reinforcement

Grinding the floor Milling or grinding individual travel paths in the aisle to achieve the necessary evenness standards is permissible for inductive or mechanical guidance, assuming it does not result in any visual or tangible height differences.

• Make sure that the overall traffic surface never exceeds the allowed tolerances and meets the required level of technology (honing the floor finish over levelled guide rails typically does not guarantee the necessary floor tolerances for trucks). • Discontinuities in the flooring, such as channels or shafts, require a minimum spacing of 200 mm to the travel paths and should be avoided in the aisle whenever possible.

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Evenness tolerances

Table 1: Permissible height differences crosswise to the travel path

This specification is based on the VDMA directive “Flooring for use by very narrow aisle industrial trucks”. Stricter requirements apply for travel paths in very narrow aisle warehouses than in all other areas of the warehouse. Tolerances per the VDMA directive must be complied with (see tables 1+2+3) in very narrow aisles and everywhere travelled with an increased load. The evenness of other surfaces must meet those tolerances of DIN 18202, Tab. 3, line 3.

Lift height (m)

Zslope

dz = Z x Zslope

bis 6

2.0

Z x 2.0 mm/m

10

1.5

Z x 1.5 mm/m

15

1.0

Z x 1.0 mm/m

Lift heights >_ 6 m require interpolation (see Fig. 2)

Zslope Permissible slope crosswise to the path between the middle of the load wheels of the industrial truck (a, b) in mm/m (the value of Zslope is specified dependent on the lift height)

Specifications for evenness for the very narrow aisle range are defined for three different areas: a.) height differences crosswise to the travel path b.) height differences longitudinally along the travel path c.) rippled variations in height differences

Z Dimension between the centres of the load wheels of industrial trucks (a, b) in m

These three factors have a decisive influence on the driving performance and non-compliance can lead to a reduction in handling performance.

dZ Maximum permissible height differences between the centres of load wheels of industrial trucks (a, b)

Height differences crosswise to the travel path The following tolerances crosswise to the travel path apply per VDMA, deviating from DIN 18202 (see Tab. 1):

Fig.1: Diagram, height difference crosswise to the travel path

a

b

dz

Z

8

Height difference = dz Track width = Z Load wheels = a, b


Example for determining Zslope: Assumption: lift height = 8 m; travel path Z = 1.5 m Calculation of Z slope using Fig. 2: Lift height = 8 m; Z slope = 1.75 mm/m Calculation of dz using Fig. 3: dz = Z x Z slope = 2.625 mm The maximum permissible height difference (dz) in this case must not exceed 2.625 mm.

Fig. 2: Example for determining Zslope

Zslope (mm/m) 2 1.75 1.5

1

0.5 8

5

10

15 T lift height (m)

Fig. 3: Example for determining dZ Zslope 2

dZ (mm)

1.75 4

1.5 1.25

3 2.625

1.0

2 1 0

2

0.5

1

1.5

2

2.5 Z (m)

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After determining the maximum permissible height difference dz, the lateral deviation of the truck at a specific height can be calculated using a formula. The general formula for determining the lateral deviation (see Fig. 4): Lateral deviation at the maximum height = Delta X = dz (mm/m) x Hx (m) Fig. 4: Determining the lateral deviation of point X

Example calculation for lift height 10 m and track width 1.0 m (see Fig. 5): A lift height of 10 m and a track width of 1.0 m produces a dz value of 1.5 mm/m Hx = height of point X = 10 m Delta X = 1.5 mm/m = 15 mm lateral deviation of point X

Fig. 5: Example calculation for lift height + 6.0 m and track width up to 1.0 m X

Delta X

Delta X

Point X

Hx

+ dz Zero line Track width

Ast

– dz

Ast Hx = height of point X above the floor b1 = safety distance

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Ast = aisle width


Evenness tolerances longitudinally along the travel path The evenness tolerances per VDMA longitudinally along the travel path are the following (see Tab. 2):

Example: The inside micrometer below a 2 m long straight edge must not be greater than 3 mm (see Fig. 6).

Table 2: Evenness tolerances longitudinally along the travel path Distance between measurements l

Gap under the ruler t

1m

2 mm

2m

3 mm

3m

4 mm

4m

5 mm

Testing the evenness is done per DIN 18202.

Fig. 6: Example of evenness tolerances longitudinally along the travel path

l=2m

t = 3 mm

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Ripple variations for industrial flooring in very narrow aisle warehouses In addition to the requirements for absolute height differences in very narrow aisles, there are also requirements for regularly reoccurring uneven surfaces. No rippled uneven surfaces or regular changes in lateral inclination may occur, as they lead to the industrial trucks swinging. Ripple variations are defined by the height differences between two adjacent points along the travel path and are measured in “ripple variation factor Fx”. This is determined from a series of height differences of multiple adjacent readings according to a specified algorithm. The smaller the Fx value, the larger the ripple variation at greater amplitudes or the more uneven the floor. In the VDMA directives, the calculation of this key figure is described in detail; a table calculation is also offered for download, enabling automatic calculation from the raw data. The directive and the calculation tool mentioned can be found on the home page of the VDMA (www.vdma.org/Branchen/Logistiksysteme). The ripple variation factor Fx calculated in this way must be complied with as per table 3.

Table 3: Ripple variation factor Fx Lift height (m)

/-FX Fx or O

15

>_ 525

10

>_ 400

up to 6

>_ 300

Lift heights > 6 m require interpolation (see Fig. 5)

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Measuring procedure for ripple variation The exact measuring method is defined in the VDMA directive as mentioned. You can find assistance in determining Fx in the schematic drawing below (see Fig. 7).

Example calculation: Assumption: lift height = 8 m; travel path Z = 1.5 m Calculation of Z slope using Fig. 2: 1.75 mm/m Calculation of dz using Fig. 3: Z x Z slope = 2.625 mm Calculation of Fx using Fig. 6: Fx >_ 350

Fig. 7: Example for determining Fx Fx 550 500 450 400 350 300 250 5

8

10

15 Lift height (m)

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The racking

Racking systems available on the market can be adapted exactly to the most varied requirements and room characteristics. Thus, the weights and load dimensions used, the loading equipment, and the industrial trucks used are the most important parameters for designing racking. Today, pallet racks are primarily used for very narrow aisle systems. They have the advantage that they can be used both manually and automatically, and facilitate direct access to all items and also order picking.

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Linde VNA directives // Racking

Pallet racks consist of vertical racks and horizontal bridge pieces (DIN EN 15620). Support beams, grating, steel panels, or particleboard can be placed on these, depending on application profile. If the distance between the inside of the stored loads for double racks is less than 100 mm, a push-through guard is mounted for protection. Free-standing pallet racks are not permanently joined to the building. They can be set up flexibly, and can be used later for other applications by switching them around. DIN EN 15512 “Stationary racking systems made of steel – adjustable pallet racks – basis for static measurement” forms the basis for static verification when building such racks. Requirements for fire protection are an another important factor when building racking storage. We recommend early contact with

the responsible agencies, construction companies, and with your insurance partner, and taking into account the spatial requirements for fire protection measures in terms of safety distances in the racking. Please also note the regulations for the load capacity of the floor. Flooring in storage facilities and the trucks used must meet the requirements of DIN EN 15635, DIN EN 15512 and DIN EN 15629 so that net weight and loads can be supported safely. The p and d stations are normally formed from the overhanging support of the last rack. The use of centering aids at the p and d stations is required for partial and fully automatic rack operation. Thus the loads from the industrial trucks with freely moveable feeder can be deposited in a specified position on the p and d station for the mandown narrow aisle truck.

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Assembly tolerances for racks and permissible deformations Per DIN EN 15620 pallet racks for very narrow aisle trucks are divided into two different classes:

Rack class 300A: Man-down narrow aisle truck with “man up” operation. Rack class 300B: Man-down narrow aisle truck with “man down” operation. The assembly tolerances are shown in Fig. 8, the associated tolerance description per DIN EN 15620 can be found in table 4.

Fig. 8: Rack assembly tolerances Front view

Side view

CX

CZ Y-direction GY

GY JX

H1 H

JZ

HB

Detail E1 H1A M X-direction

Z-direction D

E

D

Top view A1(n) A

GZ

Side view detail

B0

B1

B2

B3

Bn

HY F

Z-direction

F1

X-direction

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F


Table 4: Installation tolerances and permissible deformations of the racks according to DIN EN 15620 Horizontal tolerances for the XZ plane (mm) Measurement specification and description of the cross deviation

Building cross deviation for racking class 300

A

Deviation from the nominal size of the access width between two support uprights in any beam height

+- 3

A1

Deviation from the nominal value for the total length of the racking, cumulative number “n” for the fields, measured as close as possible to the base plate

+- 3 n

B

Misalignment of the supports in transverse direction, speed, cumulative for the Number “n” the fields measured approximately at ground level. For this class 300A applies only to the support uprights. Class 300B applies to the support uprights and the rear pillars.

+- 10 or for class 300A: +- 1,0 n for class 300B: +- 0,5 n*

B0

Deviation from the nominal size of the racking front at the transfer aisle the respective „reference line of the racking system Z ‚ measured near ground level

+- 10

CX

Deviation from the perpendicular of the frame in the X direction

+- H/500

CZ

Deviation from the perpendicular of the frame in the X direction

without fixed Hub: +- H/500 with fixes Hub: +- H/750a

D

Deviation from the nominal depth of the racking (Single or double frame)

Single frame: +- 3 Double frame: +- 6

E

Deviation from the nominal size for the aisle width about ground level

+- 5

E1

Deviation from the nominal size for the width between the rails

+5 0

E2

Deviation between the supports on one side of the guide rail

+- 5

F

Deviation from the nominal size of the aisle straightness measured approximately at ground level with respect to the “reference line aisle system X” or according to the specifications of the truck supplier

+- 10

F1

Deviation measured between next to each other uprights around Ground level in the Z direction

+- 5

GZ

Straightness of the beam in the Z direction

+- A/400

JX

Straightness of the beams in the X direction between supports in a distance HB from each other

+- 3 or +- HB/750*

JZ

Initial curvature of a stator frame in the Z direction

+- H/500

M

Deviation limits for the upper guide rail

Is set by the truck supplier or the author of the specification

TW

Beam rotation in the middle of the field

1° per m

Vertical tolerances in the Y direction (mm) Measurement specification and description of the cross deviation

Mounting tolerances for. racking class 300

GY

Straightness of the beam in the Y direction

+- 3 or +- A/500*

H1

Deviation of the top level of any beam over the H1 lower support level

300A: +- 5 or +- H1/500 300B: +- 3 or +- H1/1000*

H1A

Deviation of the top edge of the lower beam on each upright against ground level

+- 7

H3

Deviation limits for the upper guide rail, if available

If available, set by the supplier or manufacturer of the truck

HY

Deviation of the heights of the load unit between the front and rear beam in one compartment

+- 10

H

Height from the top of the foot stand level to top of the racking support

HB

Height from the top stand level to the next higher stand level

*The greater of the following values is valid

a H/500 is also permitted, provided the overhang of the pallet skids or blocks at the front bars is 75 mm or more and the skids or blocks are supported by the beams. 17


Safety distances in the rack Free compartment dimensions are the distances between the loads within the rack. A distinction is made between distances between stored pallets and the next rack bridge piece (dimension Y) and between stored pallet and upright or the next standing pallet (dimension X) or also between the pallet backs to each other (dimension Z). The more generous these values are measured to be, the faster the pallets can be stored and removed. Thus it is advisable at higher productivity to design the safety distances larger than the defined minimum distances.

Fig. 9: Minimum distances

Y

X

X1

Z

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Minimum distances to be observed: Dimension X (distance from pallet to upright): 75 mm - For rack class 300B starting at 12 m lift height: 100 mm Dimension X1 (distance from pallets to each other): 75 mm - For rack class 300B starting at 12 m lift height: 100 mm Dimension Y (distance from pallet to bridge piece): 75 mm - For rack class 300B starting at 6 m lift height: 100 m - For rack class 300B starting at 9 m lift height: 125 m - Linde recommendation: minimum distance + 25 mm Dimension X (distance from back of pallets to each other): 100 mm (also take into account here the space requirement for sprinkler pipes)

The guide systems

To take optimum advantage of the spatial requirements in the very narrow aisle, the appropriate industrial trucks make work easier with very short distances to the rack. DIN EN 1726 part 2 prescribes a minimum distance of 90 mm between the supported load and the pallet in the rack. Depending on parameters such as pallet size, truck type, and guide system, larger distances are also needed sometimes. Basically, there are two different guide systems: inductive wire guidance enables driving speeds up to 9 Km/h. Load pick up from the floor is straight forward with inductive guidance. Mechanical guide systems have high driving speeds up to 12 Km/h. Load pick up from the floor is only possible with small rails and special forks.

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Linde VNA directives // Guide systems

Mechanical guide: rail guidance

Ast Aisle width, clear width between the loads or between the racks

The mechanical guide has rollers attached to the truck and steel profiles mounted to the floor to guide the industrial truck. The laterally mounted rollers hold the truck between the profiles in the aisle centre.

F = Ast/2 Permissible deviation of the aisle width from the centre line to 20 m - F = +- 5 mm

Fig.10 shows the minimum width of the aisle (Ast) taking into consideration the relevant parameters.

b26 Clear width between the rails b6 Truck width over guide rollers b6 = b26 – 5 mm Permissible deviation: - over the entire length: -0/+5 mm - over 1 meter length: -0/+2 mm

Fig. 10: Minimum aisle width

F

F Ast

Distance between the guide rails -b26Truck width over the guide rollers -b6-

Sub-concrete

2.5 mm

20

Iron reinforcement

2.5 mm


Safety distances with mechanical guide

Distance of supported load to pallet in the rack (a21/a23) DIN EN 1726 part 2 prescribes a minimum distance of 90 mm between the supported load and the pallet in the rack. Depending on parameters such as pallet size, truck type, and guide system, larger distances are sometimes needed also. The difference in lift height guarantees maximum handling performance with maximum safety.

Distance from guide rail to load wheel A minimum distances of 50 mm is prescribed between guide rail and load wheel for the mechanical guide. In terms of safety and handling performance, a safety distance of 100 mm (see Fig.11) is preferable.

For mechanical guides, the following applies: Lift height < 7 m -> a21/a23 = min. 90 mm Lift height > 7 m -> a21/a23 = min. 120 mm

Fig. 11: Safety distance

a21/a23

min. 50 mm

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Fig. 12: The different rail guidance systems

Height of non-cast guide rails

Rail guidance types There are multiple types of rail guidance. The most commonly used profiles used in the market are L rails with a profile height of 100 mm (high rails) or 50 mm (low rails). Additionally, other heights can be implemented up to the smallest possible rail height of 38 mm. The profile rails can be both free standing as well as integrated in a concrete base (cast guide rail). Design and assembly of guide rails To make it easier to adjust the tracks of the truck in the very narrow aisle, the start of the aisle has a entry funnel of approx. 300 mm in length with an opening angle of 15°. The strongest horizontal force is achieved in this funnel and the first meters afterwards, the approx. 2500 mm long single track area. This force of up to 2500 kg occurs in the single track area, as the industrial truck is only guided with the front rollers. Then the rear rollers get into the rail guidance and thus the forces are reduced as the aisle is travelled to approx. 400 – 1000 kg.

Height of cast guide rails

To ensure secure track adjustment, we recommend using a funnel with a high profile. The guide rails are anchored in the floor after being installed. The different effects of force in the driving area and single track area require different dowelling distances. In the driving area, the distance is 500 mm. In the single track area, it is recommended to reduce it to approx. 300 mm for the first 4 dowels. This dowel spacing also applies to the front of the rail for the changeover aisle (see Fig. 13). The guide rail should be 8 mm to avoid deformations due to lateral forces. Due to the different heights of guide rails, the side guide rollers on the industrial truck require different heights: 40 – 65 mm for high guide rails 20 – 23 mm for low guide rails

Low guide rails

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Fig. 13: Design and assembly of guide rails b26

Ast

500 mm

500 mm

300 mm

300 mm

300 mm

300 mm

300 mm 15°

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Inductive wire guidance The inductive wire guidance replaces the guide rails. A wire loop routed in the floor epitomises the guide line. The guide wire is fed from a frequency generator with AC (low voltage). The magnetic field formed around the guide wire is scanned by antennas. The downstream electronics evaluate the signals and control the servo unit. This makes the truck always move centred over the guide wire.

Laying an inductive guide wire The guide wire is laid as a closed loop, and its beginning and end are connected to the frequency generator. An uneven number of aisles requires installation of an additional return (see Fig. 14). Technical data Standard frequency: 6.25 Hz Current strength: 80–120 mA (additional frequencies and current strengths on request)

Fig. 14: Laying inductive guide wires

Rack

Frequency generator

Return of an inductive guide wire

Distance between t wo guide wires with the same frequency: min. 1200 mm

Tolerances with inductive wire guidance

= Ideal wire guidance ± 5 mm

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= Maximal permissible deviation


Tolerance with inductive wire guidance Fig. 15: Minimum distance Deviation of the guide wire from the theoretical centre line over the entire aisle length +- 5 mm (see Fig. 14) is within the tolerance range. In order for these deviation tolerances to be achievable per DIN 15185 part 1, the guide wire should be routed after the racks are assembled.

140 mm

Distances for inductive guide wire As a rule, the distance from the steel reinforcement to the guide wire (c) must be at least 50 mm. A lower distance between reinforcement and guide wire is possible but must be determined using field measurement. Metal (cable ducts, expansion joint angle, etc.) must be kept at least 200 mm away from the left and right of the guide wire. Safety distance With inductive wire guidance a minimum distance of 140 mm is required (see Fig. 15) between load and truck cabin. Distance between two guide wires of the same frequency: min. 1200 mm (see Fig. 16). If this distance is not met, the magnetic fields may malfunction (exception: return lines that are not used as a travel path).

Fig. 16: Functional principle

Receiver antennas Transmitting antennas (coil)

Guide wire 10 mm

50 mm

6 mm

Iron reinforcement Sub-concrete

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Entering and exiting the aisle/changing aisles Entering the aisle With inductive wire guidance, the changeover aisle width compared to the alternative rail guidance must be enlarged by approx. 1000 mm (see Fig. 17). In the changeover aisle, the forklift truck driver drives the truck at a sharp angle in the direction of the guide wire and switches to

automated operation. The smaller the tracking angle, the faster the truck lines up (displayed by an optical and acoustic message). The guide wire should be pulled in as far as possible in the changeover aisle. The minimum dimension here is a truck length plus 500 mm (see Fig. 17). Exit from the aisle After exiting out of the aisle, the driver switches back to manual mode and the truck can be driven again freely.

Fig. 17: Entering the changeover aisle

Select the changeover aisle to be 1000 mm larger than with the mechanical guide

Maximum tracking angle 60°

500 mm minimum distance between sensor and end of guide wire

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Optimum tracking angle 45°

Position of the inductive guide wire


Frequency generator The frequency generator has connections for a max. of 8 separate loops with each up to 2000 m summing up to a total of 16000 m. It feeds the guide wire with high frequency AC. If a single driving loop is damaged this loop then fails entirely. Therefore it is recommended to reduce downtimes by splitting of the wire guidance in a warehouse in different loops.

The supply voltage is 230 V AC at 50 Hz or 115 V AC voltage at 50 Hz. The frequency can be specified between 300 Hz and 20 kHz in 10 Hz steps. Either 35 mA, 80 mA or 100 mA can be selected as adjustable loop current.

A protected, easily accessible position in the storage area should be selected for assembly of the frequency generator. If there is a power failure, an independent power source (buffer battery) can be used as emergency power supply and sustain operation for approx. 2 additional hours.

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The driver assistance system

Driver assistance systems support the driver when operating the truck and are especially used for safety in storage areas. Part of the driver assistance system is the end of aisle safety functions, heightdependent shut-off, as well as the Linde navigation system. Whereas end of aisle safety features and driving speed reduction are prescribed by DIN 15185 part 1 or DIN 15185 part 2, the Linde navigation system is a supplementary system, which can increase both the handling performance as well as avoid incorrect storage.

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Linde VNA directives // Driver assistance system

Systems for determining position General Assistance systems in very narrow aisles such as traction and lift cut-outs can be implemented with different systems. The currently available systems are magnet operated switches, reflected light sensors, bar codes and RFID Tags. Whereas magnets and reflected light sensors can be used for traction and lift cut- outs, the functionality of bar codes and RFID is expanded somewhat further and can be used with VNA navigation.

End of the aisle safety features

Lift and . raction. cut-outs

VNA. navigation

Magnets

x

x

Reflected light sensors

x

x

Bar codes

x

x

x

RFID

x

x

x

In the following, we would like to provide a brief overview of the various systems. Each of these systems has advantages and disadvantages so that no general recommendation can be given.

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Magnets Linde magnets are very small (31 mm diameter, 25 mm height) and thus very simple and cost-effective to install. Two magnets are installed in the floor at approx. 6 cm distance, one behind the other. Depending on if the south pole or the north pole magnet is driven over first, the truck detects in which direction the truck is moving and thus, if and how the truck must brake. To be able to represent different functions, there is also the option to place the magnets 150 mm or 300 mm off centre. Magnets are ideal in storage areas where simple traction and lift reductions are necessary.

Fig. 20: End of aisle safety features using floor magnets

Open end of aisle

Closed end of aisle

N

1000 N

S

30

N

S

Absolute stop with positioning move

Beginning of aisle end zone

Vmax

V-Check/ Beginning of aisle end zone

Temporary stop

A

Aisle detection with inductive guidance using reflector (A or alternative B)

Vred

300

S

Temporary stop

Middle of aisle

Vred 150

Drive direction

Start of the rack

Vmax


Reflected light sensors Linde reflectors are attached at eye level to the uprights. Attachment to the racks is cost-effective and fast. The reflectors are grouped into A, B, C, D. These each have a different function: A reflector: aisle detection, or beginning of the aisle end zone B reflector: aisle detection (alternative when A reflector is not possible). C reflector: testing the reduced target speed D reflector: absolute stop with positioning move

Fig. 21: End of aisle safety features using reflected light sensors Open end of aisle B

Closed end of aisle

C

A

Specify on site

1000

Start of the rack

D A

Absolute stop with positioning move


Vmax


Vred

V check/temporary stop

A

Vred Middle of aisle

Aisle detection with inductive guidance using a reflector (A or alternative B)

Lrack

Drive direction

Vmax

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Bar codes Linde bar codes are attached approx. 50 cm above the floor on all rails. The truck scans the bar code and can determine its exact position in the storage area. Exactly determining a location makes it possible to assign various reactions from the truck to a location. In this way, the most varied and complicated truck functions such as lift and driving restrictions can be implemented. Exactly determining a location is also the basis for Linde‘s very narrow aisle navigation system as it supports the driver during storage and removal of the correct pallets and avoids errors.

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RFID Linde RFID tags are especially small and can be installed very quickly and easily in the floor with a standard drilling machine. They work at a frequency which enables fast reading and writing on the tags. Even if the tags get wet, they are protected and retain their function. The truck reads the RFID tags and can exactly determine its position in the storage area. Exactly determining a location makes it possible to assign various reactions for the truck to a location. In this way, the most varied and complicated truck functions such as lifting and driving restrictions can be implemented. Exactly determining a location is also the basis for Linde‘s very narrow aisle navigation system as it supports the driver during storage and removal of the correct pallets and avoids errors.


End of the aisle safety features End of the aisle safety features mean stopping or braking the industrial truck without input by the operating person at the end of the very narrow aisle. This measure also applies to cross aisles with the exception of those expressly provided as escape routes which cannot be entered from outside. Please note that the above mentioned “End of the aisle safety features” system is an emergency solution. There are other braking options (depending on model) available to the driver such as generator brakes, reverse current braking, and the mechanical braking on the drive wheel.

Zones and functions Driving speed reduction From the beginning of the aisle end zone to the end of aisle, the speed is reduced from Vmax to Vred = 2.5 km/h. When driving out of the aisle Vred = 2.5 km/h. Driving stop Temporary stop At the beginning of the aisle end zone the truck is braked to a standstill. After 2 seconds, there is a new drive release in the direction of the end of aisle with Vred = 2.5 km/h. Absolute stop Braking with absolute stop is done when the end of aisle is closed. When braking is finished, the truck is stopped. A positioning move in the direction of the end of aisle can be done using the “Q“ button (acknowledgement button pressed and held) with Vred = 1 km/h. Speed check Additional control point: testing the reduced target speed Vsoll
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Height-dependent cut-offs When system-dependent components, such as joists, pipes, and cable racks restrict the effective range and height of the industrial trucks, lift-height dependent cut-offs must be provided. Bridgeable intermediate lift limitation In this interlock, the lifting movement is always switched off using a switch before reaching the critical overhead clearance. The driver, once he is convinced that the industrial truck is not in the danger area, can continue the lifting movement by pressing an acknowledge button and actuating the lift valve. When the highest height of the industrial truck has exceeded the critical height, driving is only possible at creep speed.

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Automatic lift or traction cut-out The combination of height query on the lift mast and the systems for determining position (magnets, RFID, etc.) allows this lift or traction cut-out to be automated. If an industrial truck enters such an area at a height that is currently less than the critical height, he can continue without restriction at the appropriate speed. If the industrial truck enters this area, stops there, and the lifting movement is triggered, this is switched off just before reaching the critical height. Bypassing this cut-off is not possible. If the industrial truck enters this area at a height that is currently greater than the critical height, the driving movement is braked and the lifting movement is switched off. Driving further is only possible after lowering below the critical height. Lift cut-outs are often combined with traction cut-outs.


VNA navigation Using Linde’s very narrow aisle navigation system can increase handling performance and at the same time, ensure secure storing and removing of stock by preventing errors. Additionally, the navigation system makes the work easier for the driver and also makes it possible for new drivers to quickly work efficiently.

The truck receives its transport or picking order via data transmission from the warehouse management system on its truck terminal. Using the navigation system, the truck can move in the fastest possible way from its current position to the required pallet storage location. The driver only has to steer using the drive and lift lever. This ensures that the driver has both hands within the truck contours and thus cannot be injured. The truck moves in an ideal curve to the specified pallet storage location. Storing or removing the pallet in the wrong location is ruled out.

Operation of the very narrow aisle navigation is fast, precise, and simple at the same time. The basis for all functions of Linde’s very narrow aisle navigation system is the exact determination of the truck’s position. Determining position can be done using RFID tags and using bar codes (see Fig. 18).

Fig. 18: Functional principle VNA navigation 3. Assigned pallet location

2. Diagonal driving in the aisle using a time-optimised path to the pallet storage location

1. Locating the truck using RFID tags or bar code

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This combination of position detection and detecting the required pallet storage location makes the system efficient and prevents incorrect storage. Optimised operation using position navigation saves time by up to 25%. The green line in Figure 19 shows the fastest route with the lowest energy and time consumption.

Fig. 19: Time savings with VNA navigation

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Personnel protection systems

To be able to operate a very narrow aisle warehouse, measures to protect personnel in storage areas must be taken in Germany in accordance with BetrSichV. The following two options can be considered as standard: stationary and mobile protection. Stationary protection uses a photosensor system which is mounted on the rack, and which can distinguish between people and industrial trucks. Mobile protection uses sensors mounted directly on the truck which warning the driver as soon as someone or something is too close to the vehicle.

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Linde VNA directives // Personnel protection systems

Legal regulations In accordance with the workplace regulation 1.8. , pathsways, point (3) a side clearance for pedestrians on each side of the industrial truck in a VNA aisle should be guaranteed . Although a defnite value is not given the clearance taken as a guideline is 50cm on each side which is derived from the DIN EN 349. In BetrSichV, basic options to protect persons in very narrow aisle warehouses are described as technical or structural measures. Structural measures typically do not suffice, thus only a technical solution is offered. There is a distinction here between stationary (photosensor equipment on the very narrow aisle entrances) or mobile (systems installed on the truck) systems.

Fig. 22: Truck detection

If you operate a very narrow aisle warehouse or want to start operation in a new very narrow aisle warehouse the protective measures should be on an up to date standard. In germany they should meet the performance level b.

Stationary protection Each access of the very narrow aisle is individually protected with a photosensor system. Emergency exits and access doors are normally protected by swinging doors.

Fig. 23: Personnel detection

Photosensors for truck detection

Controller Controller

Photosensors for personnel detection

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“Person authorisation” mode of operation In the “Person authorisation” mode of operation, the aisle is free for access by persons, and every attempt at truck entry would immediately trigger an visual and acoustic alarm. This alarm can only be reset by an authorised person using a key switch, who can see what is happening in the aisle. “Truck authorisation” mode of operation In the standard “Truck authorisation” mode of operation, the truck is automatically detected when entering the aisle. In this mode of operation, if a person enters the aisle, a visual and acoustic alarm is triggered. This alarm can only be reset by an authorised person using a key switch, who can see what is happening in the aisle. Truck detection by wide-angle photosensors In this solution, two wide-angle transmitters are attached on the left and right of the industrial truck and a receiver with two receiving elements is attached to the rack. The two transmitters detect the industrial truck, regardless if it enters the very narrow aisle forwards or backwards.

Mobile protection The industrial truck is equipped with laser sensors on both sides. These monitor the travel path and detect when a person is in the warning field or the alarm field. If a person is detected in the warning field, the speed is automatically reduced to creep speed (max. 2.5 km/h). If a person is detected in the alarm field, a alarm is triggered and the truck is braked automatically until standstill. For reasons of safety, the alarm can only be reset by the driver after the truck is completely at a standstill. The monitoring equipment is not active outside the very narrow aisles. Assembly of the scanner For reasons of space, the scanner can only be attached in most cases to the front side behind the fork. This means that if the fork is lowered, there is no view and thus also no safety function. In this case, the industrial truck may only drive at creep speed (max. 2.5 km/h). A magnet operated switch on the lift mast will determine if the scanner has an unencumbered view. The scanner is then activated. If there are no other speed limitations (cross aisles or the end of the very narrow aisle), the industrial truck can move at maximum speed in the very narrow aisle.

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Additional function In order to have fully functioning mobile personal protection measures, e.g. detection of drive direction, end of aisle, cross aisles, or exiting aisle, additional elements are required. Drive direction sensor A drive direction sensor is attached on one of the two non-driven trailing wheels. This detects the direction of movement as well as the speed and performs a distance measurement.

Additional functions To increase safety, additional functions are implemented using the drive direction sensor. At commissioning, the braking distance of the industrial truck is measured from full speed to standstill. Braking distance and delay are then saved in the controller. During each braking process the actual braking distance is measured and compared with the stored braking distance. The driver is notified of diminishing braking efficiency via the terminal. Afterwards, the truck can only be operated at creep speed for safety reasons.

Position detection Position detection can be performed using reflected light sensors with coded reflection marks on the rack or using aisle magnets with magnet operated switches. The first coding is located on the access to the very narrow aisle. When this coding is detected, the protection system is initialised, i.e. the drive direction sensor starts the distance measurement and determines the drive direction. The protective fields are activated.

Fig. 24: Mobile protection

Laser scanner

Alarm field

Warning field

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Linde VNA directives // Standards

Standards

Cited standards

• ISO 6292: Powered industrial trucks and tractors — Brake performance and component strength

• D IN EN 1045 Part 2: Concrete, reinforced and prestressed concrete structures - Part 2: Concrete - Specification, properties, production and conformity

• DIN EN ISO 13849 Part 1: Safety of machinery - Safety-related parts of control systems - Part 1: General principles for design

• D IN EN 1045 Part 3: Concrete, reinforced and prestressed concrete structures - Part 3: Execution of structures

• DIN EN 349: Safety of machinery - Minimum gaps to avoid crushing of parts of the human body

• DIN 18202: Tolerances in building construction - Buildings • D IN EN 18560 Part 7: Floor screeds - Part 7: Heavy-duty screeds (industrial screeds) • D IN 15185 Part 1: Warehousesystems with guided industrial trucks; requirements on the ground, the warehouse and other requirements • D IN 15185 Part 2: Industrial trucks - Safety requirement - Part 2: Use in narrow aisles

Additional standards • D IN 15184: Power operated industrial trucks; industrial trucks for rack operation, technical safety requirements and testing • F EM 9.831 Calculation principles of storage and retrieval machines. Tolerances. Deformations and clearances in the high-bay warehouse • FEM 10.3.01 Pallet racks, tolerances, deformations, and clearances

• D IN EN 1081: Resilient floor coverings - Determination of the electrical resistance • D IN EN 15620: Steel static storage systems - Adjustable pallet racking - Tolerances, deformations and clearances • V DMA directive “Floors for use with very narrow aisle industrial trucks” • D IN EN 15635: Steel static storage systems - Application and maintenance of storage equipment • D IN EN 15512: Steel static storage systems - Adjustable pallet racking systems - Principles for structural design • D IN EN 15629: Steel static storage systems - Specification of storage equipment • D IN EN 1726 Part 2: Safety of industrial trucks - Self-propelled trucks up to and including 10000 kg capacity and tractors with a drawbar pull up to and including 20000 N - Part 2: Additional requirements for trucks with elevating operator position and trucks specifically designed to travel with elevated loads

Linde Material Handling ranks among the world’s leading manufacturers. This position has been justly earned. Linde trucks excel not only with their recognized innovative technology but especially their low energy and operating costs, which can be as much as 40% less than competitors. High quality in production is matched by the standard of the services we provide. With a comprehensive network of local sales partners, we are at your call around the clock and around the world.

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Linde Material Handling GmbH, Postfach 10 0136, 63701 Aschaffenburg, Germany Phone +49.60 21.99-0, Fax +49.60 21.99-15 70, www.linde-mh.com, [email protected]

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Guidelines for VNA (Very Narrow Aisle) Forklift and Racking System.pdf

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