Chapter 16
Parallel Keys According to DIN 6892

    16.1   General
    16.2   Scope of DIN 6892
    16.3   Types of Parallel Keys
    16.4   Surface Pressure
    16.5   Permitted Surface Pressure
    16.6   Application Factor
    16.7   Load Factor
    16.8   Load Distribution Factor
    16.9   Friction Factor
    16.10   Load Direction Changing Factor
    16.11   Load Peak Frequency Factor
    16.12   Support Factor and Hardness Influence Factor
    16.13   Inputs for Calculation Method B
    16.14   Some Additional Information On Method C
    16.15   Design Recommendations of Parallel Keys According to DIN 6892
    16.16   Automatic Dimensioning Functions (Calculator Button)
    16.17   Material Selection
    16.18   Selection and Geometry of Parallel Keys
    16.19   Input of Individual Parallel Keys
    16.20   The Button ‘Redo’ and ‘Undo’
    16.21   Message Window
    16.22   Quick Info: Tooltip
    16.23   Calculation Results
    16.24   Documentation: Calculation Report
    16.25   How to Save the Calculation
    16.26   The Button ‘Options’
    16.27   Calculation Example: Parallel Key According to DIN 6892

16.1 General

A parallel key is a positive shaft-hub-connection. The torque is transmitted from the shaft to the hub via the parallel key. The main purpose of the parallel key is to transmit static and quasi-static torques. The parallel key can be used with limitations also for swelling and alternating torques. In case a good assembly and disassembly of the shaft-hub-connection are required or necessary (e.g., replacement or repair), then a parallel key may be used. A shearing off of the parallel key does not happen very often and occurs only in the event of overloading. The fretting corrosion due to rotating bending and/or torsional oscillation has been proven in numerous endurance tests and is usually the crucial factor which leads to the failure of the shaft-hub-connection.

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Figure 16.1: General overview

For the proof of strength of parallel keys, it is necessary to check the following factors:

In DIN 6892 a distinction is made between different methods for the proof of strength for parallel keys: method A, B and C.

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Figure 16.2: Selection of method
Method A

This method is an experimental proof of strength under conditions of practice and/or an extensive stress analysis of the entire parallel key connection, consisting of shaft, parallel key and hub.

Method B

The dimensioning takes place due to a detailed consideration of the occurring surface pressures. In addition, the proof of strength for the shaft is carried out according to the nominal stress concept.

Method C

It is a rough calculation of the surface pressure and resulting estimation of the shaft stress.

16.2 Scope of DIN 6892

The calculation is based on DIN 6892. The DIN standard specifies the following scope:

16.3 Types of Parallel Keys

The geometry of the parallel keys can be selected according to DIN 6885-1, DIN 6885-2 and DIN 6885-3. This geometry selection includes the standard lengths of parallel keys. The supporting length is determined from the standard length and the chosen parallel key type. There are various types of parallel keys - the types A to J are available.

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Figure 16.3: Parallel key types A to D

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Figure 16.4: Parallel key types E to J

The supporting length \(l_{tr}\) for the different types of parallel keys is calculated as follows:

\(l_{tr}\)is the supporting length

\(l_{PF}\)is the standard length

\(b\)is the width

For nonstandard parallel keys, it is possible to define an individual parallel key geometry and supporting lengths. The different keyway depths in shaft and hub as well as the chamfer of the parallel key are taken into consideration for the calculation. For method B, the chamfer on the shaft and hub keyway is additionally integrated into the calculation.

If you choose to enter the supporting length manually, the supporting length \(l_{2tr}\) of the hub keyway can be smaller than \(l_{tr}\) of the parallel key. For this case, according to DIN 6892, the length \(l_{1tr}\) of each extended part may be calculated as carrying up to maximum \(1\times b\). For a safe calculation, the eAssistant software uses the most conservative case and this exceptional case will not be considered automatically.

16.4 Surface Pressure

The effective surface pressure between parallel key and shaft or hub keyway wall must not exceed the permissible value. The permissible values result from the material strength - for ductile materials from the yield point (\(R_{p0,2}\) and/or \(R_{e}\)) and for brittle materials from the tensile strength \(R_{m}\). The calculation can be run by using less common metallic materials. The following strength criteria have to be fulfilled with the appropriate safeties:

\[p_{1,2eqzul} = f_{W}\cdot p_{zul} \quad \mbox {and} \quad S_{Feq} = \frac {p_{eqzul}}{p_{eq}}\]\[p_{1,2maxzul} = f_{L}\cdot p_{zul} \quad \mbox {and} \quad S_{Fmax} = \frac {p_{maxzul}}{p_{max}}\]

\(f_{W}\)is the load direction changing factor and \(f_{L}\) is the load peak frequency factor. The load direction changing factor considers the influence of the number of load direction changes on the permissible surface pressure. The load peak frequency factor evaluates the influence of the load peaks on the maximum surface pressure.

The calculation method applies for one-sided stress and with restriction for an alternating stress of the parallel keys. The surface pressure is determined from the torque that is transmitted.

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Figure 16.5: Geometry and surface pressure on the parallel key connection

The supporting keyway depths \(l_{1tr}\) and \(l_{2tr}\) between parallel key and shaft as well as hub keyway wall are given by the following equations. Therefore, a \(45^{\circ }\) chamfer and radius on the parallel key as well as on the shaft and hub keyway edge are considered according to the figure above:

16.5 Permitted Surface Pressure

\(f_{S}\)is the support factor

\(f_{H}\)is the hardness factor

16.6 Application Factor

The application factor \(K_{A}\) is determined for the calculation of the equivalent torque \(T_{eq}\) (similar to the gear calculation according to DIN 3990) with the following table:

Application Factors \(K_{A}\) According to DIN 3990-1: 1987-121
Working Characteristics
Working Characteristics of the Driven Machine




of the Driving Machine Uniform Light shocks Moderate shocks Heavy shocks
Uniform 1.0 1.25 1.5 1.75
Light shocks 1.1 1.35 1.6 1.85
Moderate shocks 1.25 1.5 1.75 2.0
Heavy shocks 1.5 1.75 2.0 2.25 or higher
1 from: DIN 3990 Part 1, December 1987, p. 55, table A1

16.6.1 Working Characteristics of the Driving Machine

Uniform: e.g., electric motor, steam or gas turbine (small, rarely occurring starting torques)

Light shocks: e.g., electric motor, steam or gas turbine (large, frequently occurring starting torques)

Moderate shocks: e.g., multiple cylinder internal combustion engines

Heavy shocks: e.g., single cylinder internal combustion engines

16.6.2 Working Characteristics of the Driven Machines

Uniform: Steady load current generator, uniformly loaded conveyor belt or platform conveyor, worm conveyor, light lifts, packing machinery, feed drives for machine tools, ventilators, light-weight centrifuges, centrifugal pumps, agitators and mixers for light liquids or uniform density materials, shears, presses, stamping machines, vertical gear, running gear

Light shocks: Non-uniformly (i.e. with piece or batched components) loaded conveyor belts or platform conveyors, machine-tool main drives, heavy lifts, crane slewing gear, industrial and mine ventilators, heavy centrifuges, centrifugal pumps, agitators and mixers for viscous liquids or substances of non-uniform density, multi-cylinder piston pumps, distribution pumps, extruders (general), calendars, rotating kilns, rolling mill stands, continuous zinc and aluminium strip mills, wire and bar mills

Moderate shocks: Rubber extruders, continuously operating mixers for rubber and plastics, ball mills (light), wood-working machines (gang saws, lathes), billet rolling mills, lifting gear, single cylinder piston pumps

Heavy shocks: Excavators (bucket wheel drives), bucket chain drives, sieve drives, power shovels, ball mills (heavy), rubber kneaders, crushers (stone, ore), foundry machines, heavy distribution pumps, rotary drills, brick presses, de-barking mills, peeling machines, cold strip c, e, briquette presses, breaker mills

16.7 Load Factor

Due to deviation in form and position of a single parallel key, an unbalanced or uneven carrying of two parallel keys, that are arranged evenly around the circumference, occurs. Thus, the reduced load capacity of the parallel key is considered by the load factor \(K_{v}\). In practice, not more than two parallel keys are used because of the load distribution that is difficult to determine.

\[K_{v}=\frac {1}{i \cdot \varphi }\]

Compared to the calculation of the equivalent surface pressure, a higher load part \(\varphi \) can be estimated for the determination of the maximum surface pressure because a torque \(M_{tmax}\) occurring in several load peaks leads to a higher load part by deformation on the parallel key and keyway ground. Using these load parts, ductile materials with pronounced yield point as well as sufficient manufacturing accuracy are required. For brittle materials (e.g., gray cast iron), there is no established knowledge about the load capacity using two parallel keys.

16.8 Load Distribution Factor

The load distribution factor \(K_{\lambda }\) takes an uneven load distribution into consideration along the keyway length as well as the ratio of load in and output. For using two parallel keys, the unbalanced carrying is considered by the following assumption:

The factor \(K_{\lambda }\) is dependent upon the kind of load in and output position. Regardless of the torque flow direction, three cases are distinguished.

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Figure 16.6: Kind of load application

For a stepped hub, it means (see above figure):

\(D_{1}\)Small outer diameter of stepped hub

\(D_{2}\)Large outer diameter of stepped hub

\(a_{0}\)Distance between the axial cutting planes through N and W

\(c\)Width of the hub with \(D_{2}\) within the carrying part of the parallel key, i.e., \(c \leq l_{tr}\)

\(D\)is the outer diameter of the hub or the outer diameter of the alternative cylinder with equal torsional stiffness. The alternative outer diameter is calculated as follows:

\[D = \frac {D_{2}} {\sqrt [4] {\left (\frac {D_{2}}{D_{1}}\right )^{4}\left (1-\frac {c}{l_{tr}}\right ) + \frac {c}{l_{tr}}} }\]

Depending on \(a_{0}/l_{tr}\), the factor \(K_{\lambda e}\) is determined by using the figures 3, 4 and 5 in DIN 6892. These diagrams are integrated into the calculation module and are valid for a specific ratio \(a_{0}/l_{tr}\) \((a_{0}/l_{tr} = 0; 0.5; 1)\). For other ratios \(a_{0}/l_{tr}\), the values are determined from two diagrams by interpolation.

16.9 Friction Factor

For an interference fit, part of the torque is transmitted by friction. The friction factor \(K_{R}\) considers that. But it is taken into consideration only for the calculation of the maximum effective surface pressure \(p _{max}\). For a dynamic load, an interference fit stops the occurrence of fretting corrosion. A clearance fit or interference fit adversely affects the shaft strength. For the determination of the friction factor, a minimum friction torque \(M_{tRmin}\) of the interference fit is assumed. According to DIN 7190, this can be obtained for a hole without keyway. The joint pressure, that is reduced due to the parallel key in comparison to the hole without keyway, is considered by the factor \(q\). Thus, the friction torque, effective for the power transmission, is decreased. As a first approximation, \(q = 0.8\) can be specified for a parallel key.

With the maximum load peak torque \(M_{tmax}\), occurring during the entire operation time, it applies:

\[M_{tmax} > q_{max} \cdot M_{tRmin}\]

\[K_{Rmax} = \frac {M_{tmax} - q_{max} \cdot M_{tRmin}}{M_{tmax}} \quad \mbox {with} \quad q_{max} = 0.8\]

For \(Mt_{tmax}\leq q_{max}\cdot M_{tRmin}\) the load peak torque is transmitted by friction. In this case, the surface pressure, occurring in the parallel key, is not relevant. A check of the maximum surface pressure \(p_{max}\) is not necessary according to DIN 6892. However, it is integrated into the calculation.

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Figure 16.7: Friction factor

Please note: Interference fit is not allowed for brittle materials (e.g., gray cast iron).

16.10 Load Direction Changing Factor

Parallel key connections are only conditionally usable during changing the direction of torque. However, the rating life is limited if it comes to constant slipping between shaft and hub and thus to a deflection of the parallel key connection. There are two different cases:

Case 1: One-sided load of the parallel key during alternating load direction. The maximum torques in reverse direction (against the main load direction) do not exceed the effective part of the minimum friction torque.

\[M_{tmaxRev} \leq q_{eq} \cdot M_{tRmin} \quad \quad \quad f_{W} = 1\]

Case 2: Alternating load of the parallel key during alternating load direction. The maximum torques exceed the effective part of the minimum friction torque in both directions.

\[M_{tmax} > q_{max} \cdot M_{tRmin}\quad \mbox {and} \quad M_{tmaxRev} > q_{max} \cdot M_{tRmin} \quad \quad \quad f_{W} \leq 1 \]

In case 2, the load direction changing factor \(f_{W}\) is dependent upon the frequency \(N_{W}\) of changes of load direction for the parallel key.

Load direction changes, that occur due to special cases, have to be considered as well.

16.11 Load Peak Frequency Factor

Load peaks occur when the torque clearly exceeds the equivalent torque \(M_{teq}\). Special cases may occur due to starting impacts, short-circuit torques, emergency breaking torques, abrupt blockings etc. The frequency \(N_{L}\) of the load peaks has to be estimated during the entire operating time.

For a single load peak, depending on the ductility of the material, the 1.3 to 1.5 times the permanent surface pressure is allowed. The progress of \(f_{L}\) for ductile and brittle materials over the frequency is shown in the following figure.

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Figure 16.8: Load peak frequency factor \(f_{L}\)

16.12 Support Factor and Hardness Influence Factor

Using the support factor \(f_{S}\), a supporting effect can be considered that occurs for compressive stress components. From experience, the supporting effect for hubs is larger due to the higher stressed material volume than for shafts and parallel keys.

The hardness influence factor \(f_{H}\) is determined from the ratio of surface strength to core strength for case-hardened components. By the hardness influence factor, an increasing of the permissible surface pressure is considered (see table: Support and hardness influence factors for different materials). If the material properties are not well known, then the smaller value for \(f_{S}\) should be used.

Please note: If you select the entry ‘user defined’ from the material database, you can define your individual support factor \(f_{S}\).

Support and Hardness Influence Factors for Different Materials2
Component Material \(f_{S}\) \(f_{H}\)
Parallel key Structural steel according to DIN EN 10025 1.1 - 1.4 1.0
Bright steel according to DIN EN 10277-5 1.1 - 1.4 1.0
Heat-treated steel according to DIN EN 10083-1 and DIN EN 10083-2 1.1 - 1.4 1.0
Case-hardened steel according to DIN EN 10084 1.1 - 1.4 1.15

Shaft Structural steel according to DIN EN 10025 1.3 - 1.7 1.0
Heat-treated steel according to DIN EN 10083-1 and DIN EN 10083-2 1.3 - 1.7 1.0
Case-hardened steel according to DIN 17210 1.3 - 1.7 1.15
Gray cast iron with lamellar graphite according to DIN EN 1563 1.3 - 1.7 1.0
Steel casting according to DIN 1681 1.3 - 1.7 1.0
Gray cast iron with lamellar graphite according to DIN EN 1561 1.1 - 1.4 -
Hub Structural steel according to DIN EN 10025 1.5 1.0
Heat-treated steel according to DIN EN 10083-1 and DIN EN 10 083-2 1.5 1.0
Case-hardened steel according to DIN EN 17210 1.5 1.15
Gray cast iron with spheroidal graphite according to DIN EN 1563 1.5 1.0
Steel casting according to DIN 1681 1.5 1.0
Gray cast iron with lamellar graphite according to DIN EN 1561 2.0 -
2 from: DIN 6892:2012-08, p. 25, appendix B, table B.1. Support and Hardness Influence Factors for Different Materials

16.13 Inputs for Calculation Method B

The calculation method B provides a more precise way to determine the surface pressure. The strength of the shaft is verified according to the nominal stress concept. Select method B from the listbox. The calculation method B requires some additional inputs. Click the button ‘Input data method B’.

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Figure 16.9: Button ‘Input method B’

A new window is opened.

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Figure 16.10: Inputs for method B

The following input can be defined:

16.14 Some Additional Information On Method C

The calculation method C according to DIN 6892 is suitable only for a rough calculation of parallel keys. The method is based on the following simplifications:

Limitations:

16.15 Design Recommendations of Parallel Keys According to DIN 6892

16.15.1 Hub Geometry and Load Output from the Hub

The sections for the load input and load output should be designed with the largest possible distance \(a_{0}\).

16.15.2 Parallel Key Length

The parallel key length \(l_{tr}\) should be selected so that for the ratio \(l_{tr}/d\), a value of 1,3 is not significantly exceeded. The reason for this is the uneven carrying of the key over the length.

16.15.3 Shaft Shoulders

A shaft shoulder located at the end of the groove has a favorable effect on the dynamic strength compared to the shaft that is not shouldered. Cutting the groove into the shaft shoulder does not change the notch factor. Special end mill grooves (see parallel key type N1 according to DIN 6885-1) should be preferably be placed in the larger shaft diameter.

16.15.4 Keyway Form in the Shaft

The side milling grooves (see prallel key type N2 according to DIN 6885-1) reduces the maximum bending stress most significantly compared to the round-ended form N1.

16.15.5 Parallel Key Form

The design strength of parallel keys with an end mill groove (see form N1 according to DIN 6885-1) is independent of the parallel key type used (round-ended parallel key; type A according to DIN 6885-1 or straight-ended parallel key; type B according to 6885-1).

A tightly screwed parallel key (see parallel key type E according to DIN 6885-1) leads to lower stresses compared to parallel key type A.

16.16 Automatic Dimensioning Functions (Calculator Button)

The button for the dimensioning functions is marked by a calculator symbol and is located next to the input fields. If you click on the dimensioning buttons, you get a suggestion for an appropriate input value. The calculation of the value is carried out so that the given minimum safety is fulfilled. The default value for the minimum safety is set to ‘1.2’. Clicking the button ‘Options’ allows you to change this value. The following dimensioning functions (calculator button) provide you with optimal support:

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Automatic dimensioning of the shaft diameter

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Automatic dimensioning of the nominal torque

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Automatic dimensioning of the maximum load peak torque

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Automatic dimension of the standard length

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Automatic dimensioning of the supporting length

16.17 Material Selection

Select an appropriate material directly from the listbox. Clicking the button ‘Material’ opens the material database. Please select the material from the list. You will get detailed information on the material. The two cursor keys ‘Up’ and ‘Down’ of your keyboard allows you to navigate through the material database, so you can compare the different material properties with each other. That applies for shaft, hub and parallel key.

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Figure 16.11: Material selection
Define Your Own Material

In case there is no material that will fulfill the design requirements, then simply define your individual material. Select the option ‘User defined’ and all inputs and options are enabled and you can specify your individual material very easily. Your inputs will be saved to the calculation file. Please be advised that changing the material will delete your defined inputs and you have to enter the inputs again.

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Figure 16.12: Own material

16.18 Selection and Geometry of Parallel Keys

Click the button ‘Parallel key’ in order to select parallel keys quickly and easily.

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Figure 16.13: Button ‘Parallel key’

The geometry database will be opened. The database allows you to select a parallel key.

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Figure 16.14: Selection dialog for parallel key geometry

The database provides the parallel key selection according to DIN 6885 sheet 1 to 3. The parallel key forms A to J as well as the parallel key size, including the lengths, can be selected. Clicking the button ‘OK’ confirms yur inputs and leads you back to the the main mask.

16.19 Input of Individual Parallel Keys

The geometry database offers the possibility to calculate individual parallel keys. You can define the geometry of parallel keys as you wish and different from the DIN standard. The parallel key forms from A to J are also available. In order to define your individual parallel key, click the button ‘Parallel key’ to open the parallel key database. Enable the option ‘Own input’ and choose the suitable dimensions from the list or enter your own values directly into the input field.

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Figure 16.15: Own input

16.19.1 Supporting Length of Individual Parallel Keys

It is possible to define a supporting length for your individual parallel key. Select ‘User defined input’ from the listbox and enter your own value for the supporting length.

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Figure 16.16: Own input of supporting length

You can specify different supporting length for the shaft and hub. Place a checkmark in order to enable the input field and enter a value for the supporting length.

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Figure 16.17: Supporting length for shaft and hub

16.20 The Button ‘Redo’ and ‘Undo’

The button ‘Undo’ allows you to reset your input to an older state. The button ‘Redo’ reverses the undo.

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Figure 16.18: Button ‘Redo’ and ‘Undo’

16.21 Message Window

The calculation module provides a message window. This message window displays detailed information, helpful hints or warnings about problems. One of the main benefits of the program is that the software provides suggestions for correcting errors during the data input. If you check the message window carefully for any errors or warnings and follow the hints, you are able to find a solution to quickly resolve calculation problems.

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Figure 16.19: Message window

16.22 Quick Info: Tooltip

The quick info feature gives you additional information about all input fields and buttons. Move the mouse pointer to an input field or a button, then you will get some additional information. This information will be displayed in the quick info line.

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Figure 16.20: The quick info

16.23 Calculation Results

All important calculation results, such as the safeties for the operation load or at the maximum load for all three components (shaft, hub and parallel key) or the equivalent pressure will be calculated during every input and will be displayed in the result panel. A recalculation occurs after every data input. Any changes that are made to the user interface take effect immediately. Press the Enter key or move to the next input field to complete the input. Alternatively, use the Tab key to jump from field to field or click the ‘Calculate’ button after every input. Your entries will be also confirmed and the calculation results will displayed automatically. If the result exceeds certain values, the result will be marked red.

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Figure 16.21: Calculation results

16.24 Documentation: Calculation Report

After the completion of your calculation, you can create a calculation report. Click on the ‘Report’ button.

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Figure 16.22: Button ‘Report’

You can navigate through the report via the table of contents that provides links to the input values, results and figures. This calculation report contains all input data, the calculation method as well as all detailed results. The report is available in HTML and PDF format. The calculation report saved in HTML format, can be opened in a web browser or in Word for Windows. You may also print or save the calculation report:

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Figure 16.23: Calculation report

16.25 How to Save the Calculation

When the calculation is finished, it is easy to save the calculation. You can save your calculation either to the eAssistant server or to your computer. Click on the button ‘Save’.

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Figure 16.24: Button ‘Save’

Before you can save the calculation to your computer, you need to activate the checkbox ‘Local’ in the calculation module. A standard Windows dialog for saving files will appear. Now you will be able to save the calculation to your computer.

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Figure 16.25: Windows dialog for saving the file

In case you do not activate the option in order to save your files locally, then a new window is opened and you can save the calculation to the eAssistant server. Please enter a name into the input field ‘Filename’ and click on the button ‘Save’.

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Figure 16.26: Save the calculation

16.26 The Button ‘Options’

Click the button ‘Options’ in order to change the default settings.

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Figure 16.27: Button ‘Options’

The button ‘Options’ allows you to define the minimum safeties. Additionally, there is the possibility to switch the unit system or enter the number of decimal places for the output of the numerical values in the report.

16.27 Calculation Example: Parallel Key According to DIN 6892

16.27.1 Start the Calculation Module

Please login with your username and your password. To start the calculation module for parallel keys, please click the menu item ‘Connections’ on the left side and then select ‘Parallel keys’.

16.27.2 Calculation Example

A strength calculation for the following shaft-hub-connection is required (see also DIN 6892, Example E.2). Enter the following values into the input fields:

Shaft diameter = 60 mm

Application factor = 1.75

Outer diameter hub \(D_{2}\) = 120 mm

Calculation method = B

Operation nominal torque \(M_{tnom}\) = 1,950 Nm

Min. frictional torque \(M_{tRmin}\) = 1,250 Nm

Max. load peak torque \(M_{tmax}\) = 3,900 Nm

Load peaks \(N_{L}\) = 500

Material shaft = C45 hardened and tempered

Material hub = 34CrNiMo6 hardened and tempered

Parallel key = DIN 6885.1 AB 18 x 11 x 100

Material parallel key = 34CrNiMo6 hardened and tempered

Standard length parallel key = 100 mm

Number of parallel keys = 1

Inputs Method B:

Kind of load = Alternating torque with a slow torque increase

Changes of load direction = \(10^{6}\)

Max. reverse torque \(M_{tmaxRev}\) = 3,900 Nm

Small outer diameter \(D_{1}\) = 120 mm

Large outer diameter \(D_{2}\) = 120 mm

Width of hub within \(l_{tr}\) = 91 mm

Axial distance \(a_{0}\) = 45.5 mm

Chamfer/radius on shaft keyway edge \(s_{1}\) = 1.0 mm

Chamfer/radius on shaft keyway edge \(s_{2}\) = 1.0 mm

16.27.3 Start the Calculation

Please start to enter the values into the input field. All important calculation results will be calculated during every input and will be displayed in the result panel. A recalculation occurs after every data input.

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Figure 16.28: Input of the values

During the input of the values it can happen that the results will be marked in red. Nevertheless, please continue to input the data as usual. For the load peaks \(N_{L}\), please select the entry ‘User defined input’ from the listbox. Enter the the value ‘500’ into the adjacent input field.

16.27.4 Calculation Method B

The direction of the torque is reversed and a rough calculation according to Method C is not possible. It is recommended to use the calculation method B. Select the calculation method B from the listbox and click the button ‘Input data method B‘.

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Figure 16.29: Calculation method B

Clicking this button opens the window ‘Input data method B’ and allows you to enter the other input values.

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Figure 16.30: Calculation method B

Please note: If, at a later time, you need to change certain values, then click the button ‘Input data method B’ and the input mask will open again.

Input Values for Shaft and Hub

Specify the material for the shaft and the hub. The material for the shaft is ‘C45 hardened and tempered’. The required material for the hub is ‘34CrNiMo6 hardened and tempered’. Both materials can be selected from the listbox.

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Figure 16.31: Material selection for shaft and hub

Select the material either from the listbox or click the button ‘Material’ to open the material database. The database allows you to choose the material. You also get detailed information on the kind of material, hardness factor \(f_{H}\), yield point as well as support factor \(f_{S}\).

Input Values for Parallel Key

The parallel key selection according to DIN 6885 sheet 1 to 3 makes it easier to choose the required parallel key. You can also select the geometry and size of the parallel key. The database also provides the standard lengths of the parallel keys. The dimensions of the parallel key are as follows: DIN 6885.1 AB 18 x 11 x 100

Standard Length

In order to define the standard length of the parallel key, select the value ‘100’ from the listbox.

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Figure 16.32: Standard length
Selection of the Parallel Key Geometry

Click on the button ‘Parallel key’ to select the shape of the parallel key.

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Figure 16.33: Button ‘Parallel key’

The geometry selection shows the suitable parallel key. Select the parallel key geometry ‘DIN 6885 sheet 1-8/1968’ as well the shape ‘AB’ from the listbox. Click the button ‘OK’ to confirm the values.

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Figure 16.34: Selection dialog for the parallel key

Selection of Material

Select the material ‘34CrNiMo6 hardened and tempered’ from the listbox. If you need further information on the material, click the button ‘Material’ to open the material database.

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Figure 16.35: Material for parallel key
Supporting Length and Number of Parallel Keys

The supporting length \(l_{tr}\) is determined automatically from the selected standard length. You can use the listbox to select the number of parallel keys. For our calculation example we specify one parallel key.

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Figure 16.36: Supporting length and number of parallel key

16.27.5 Calculation Results

All important calculation results, such as the safeties for the operation load or at the maximum load for all three components (shaft, hub and parallel key) or the equivalent pressure will be calculated during every input and will be displayed in the result panel. A recalculation occurs after every data input. Any changes that are made to the user interface take effect immediately. You will get the results for the equivalent pressure and for the pressure at load peak as well as the safety at operation load and the safety at peak load.

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Figure 16.37: Calculation results

In our calculation example the safeties for the shaft, the hub and the parallel key are marked red. That means the minimum safeties are not fulfilled. In addition, you get also an appropriate message in the message window. The parallel key is not suitable for our calculation example.

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Figure 16.38: Message window

Minimum Safety: Dimensioning of the Shaft Diameter

Use the automatic dimensioning function (calculator button) in order to determine the shaft diameter. With just one click, the program automatically determines the shaft diameter so that the required minimum safety of ‘1.2’ will be fulfilled. To do so, please click the calculator button next to the input field of the shaft diameter.

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Figure 16.39: Dimensioning button for the shaft diameter

Now the new shaft diameter is determined.

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Figure 16.40: New shaft diameter

The shaft diameter is now \(d\) = 75.1 mm. With this diameter the minimum safety of ‘1.2’ is achieved and the parallel key is suitable for this application. The safety can even be increased by selecting another material.

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Figure 16.41: Calculation result

Due to the new dimensioning, the shaft diameter is now larger. A new size of the parallel key was determined automatically. Click the button ‘Parallel key’ and the larger parallel key is displayed automatically.

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Figure 16.42: New parallel key

16.27.6 Documentation: Calculation Report

Use the button ‘Report’ to generate the calculation report very fast. This report contains the calculation method, all input values as well as the detailed results.

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Figure 16.43: Button ‘Report’

The calculation report contains a table of contents. You can navigate through the report via the table of contents that provides links to the input values, results and figures. The report is available in HTML and PDF format. Calculation reports, saved in HTML format, can be opened in a web browser or in Word for Windows.

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Figure 16.44: Calculation report

You may also print or save the calculation report:

16.27.7 How to Save the Calculation

When the calculation is finished, it is easy to save the calculation. You can save your calculation either to the eAssistant server or to your computer. Click on the button ‘Save’.

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Figure 16.45: Button ‘Save’

Before you can save the calculation to your computer, you need to activate the checkbox ‘Local’ in the calculation module. A standard Windows dialog for saving files will appear. Now you will be able to save the calculation to your computer.

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Figure 16.46: Windows dialog for saving the file

In case you do not activate the option in order to save your files locally, then a new window is opened and you can save the calculation to the eAssistant server. Please enter a name into the input field ‘Filename’ and click on the button ‘Save’.

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Figure 16.47: Save the calculation

Our manual is improved continually. Of course we are always interested in your opinion, so we would like to know what you think. We appreciate your feedback and we are looking for ideas, suggestions or criticism. If you have anything to say or if you have any questions, please let us know by phone +49 (0) 531 129 399-0 or email eAssistant@gwj.de.