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This calculation module enables you to determine the deviations of different tolerance fits for a given nominal diameter very easily and fast. Here all IT classes and tolerance fields according to the standard DIN ISO 286 are available. The program determines only interferences or expected as an input.
A clearance indicates a negative interference.
The upper part, the ‘selection of fits’, calculates the minimum and maximum interference by the determined deviations (UK= ei-ES and Ug=es-EI). Positive values indicate an interference, negative values a clearance.
The upper part of the fit calculation allows to select the tolerance field for shaft and hub very easily via listboxes.
The program determines the lowest and highest interference or the clearance of the selected fit. Thereby, the calculator displays also the type of fit:
In addition, all deviations for the shaft and hub can be entered directly. Then select the option ‘Activate input of user defined tolerances’.
For the calculation of possible fits the desired interferences must be entered by the user. Here the clearance is
also specified as a negative interference.
Examples:
and 59 
interference:
= 18, U
= 59.
clearance and 15 
interference:
= -18, U
= 15.
and 18 
clearance:
= -42, U
= -18.
Tolerance fits can be searched on the basis of default settings. For the dimensioning of a fit you have different possiblities.
The button ‘Search fits’ shows you all possible fits. There the message ‘More than 500 fits were found. Only preferred fits are shown’ appears. Please confirm this message with ‘OK’. Then select a fit from the listbox.
The option ‘Show only preferred fits’ is activated automatically and all preferred fits will be displayed in the listbox.
Additional, the following options are available
Activate the options and take over the above mentioned tolerances from the upper ‘selection of
fit’.
A limitation of the IT scope is also possible:
The following section gives some guidance on selecting fits according to E. & K. Felber. There
are features that can be expected in general during the assembly. The assembly rules specify the
character of the fit and all features correspond to the mean value of fits. The list contains fits that
are used frequently. Almost all fits can be formed in quality (e.g., from H8/f8 to H8/f7 to H6/f6). In
general, the standard fits (e.g., H8/f7) can be used. According to the function, you have to select fine
qualities (e.g., H6/f6) for larger requirements (requirements for accuracy and uniformity). The following
examples are taken from the mechanical engineering and cannot to be considered as complete in any
detail.
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The parts are assembled and tightened and have a strong interference. The parts are pressed together or assembled into position while hot and cooled. In general, a safety device against torsion or shifting in lengthwise direction is not necessary.
Spur gears that are mounted tightly on a shaft, couplings, collar rings, press rings, wheel rims, bearing bushings in housings, bushings in gear hubs, tight pivots, bushings made of synthetic resin pressed material, parts which cannot be loosened by large forces.
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The parts are mounted against each other. High pressure is necessary to join and separate the parts. Due to clearance, the parts have to be secured against torsion.
Bearing bushings at machine tools, wheel rims on wheel bodies, levers and cranks on shafts, impact-loaded parts, bushings in basic bodies, gears and couplings on shafts
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Parts sit tightly on top of each other. Joining and separating cases require large expenditure of energy by using a hammer, parts have to be secured against torsion and shifting.
Pulleys, gears, bushings, lever on shafts, cranks for lower forces, piston pins in pistons, coupling pins, fixing pins
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Parts stick together and can be joined and separated by using some hammer blows without enormous expenditure of energy. Parts have to be secured against torsion and shifting.
Coupling parts, pulleys, flywheels, handwheels, hand levers on shafts, gears on machine tool spindles, bearing bushings in wheels and in basic bodies, fixing pins, pins, bolts, centralisations, coupling halves and gears on shaft ends of electric motors over Ø 50mm.
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Easy to join by hammer blows, often movable by hand, not intended for functional shifting, applicable for parts which have to be disassembled very often, a securing against torsion and shifting is possibly necessary.
Change gears, gears, pulleys, adjusting rings, bushings, bearing bushings and handwheels which have to be removed very often, centralisations, coupling halves and gears on shaft ends on electric motors up to Ø 50mm.
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Parts can be moved manually by using lubricants. Still usable for a slow shifting.
Centralisations, change gears, adjusting rings, coupling parts wedged on shafts, tools on arbors (e.g., milling cutters on milling-machine arbor), idler bushings, handwheels on spindles, spacer sleeves, sealing rings, all kind of guides, tailstock sleeve, plain bearings with very small clearance, chain wheels, large gears
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Parts fit easily into each other and are easy to move.
Less important centralisations, adjusting rings, crank handles, gears, couplings, pulleys which have to be moved over shafts, idler bushings, use of cold finished round steel (round steel, finish polishing made of tool steel, cold work steel, high-speed steel)
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Parts can be easily stuck together. Clearance as low as possible with relatively large manufacturing tolerances.
Not so important centralisations, parts which are to be stuck together, soldered or welded, parts that are pinned, bolted or clamped on shafts, spacer sleeves, hinge and snap pins, extensive use of cold drawn steel bar (e.g., round steel, uncoated according to ISO tolerance field h9/h11)
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Parts are easily movable and twistable but without noticeable clearance.
Bearings for high requirements, change gears, movable coupling parts, indexing pin, valve lever
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Parts have noticeable clearance and are movable into each other.
Main bearing on machine tools, gear shafts, main bearing for shafts that run in two bearings, cardan shafts, camshafts, crankshafts, bearing bushes, sleeves and floating sleeves on shafts, timing shafts, slide blocks in guides, snap rings
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Parts are movable, run easily and have large clearance.
Shafts with multi-bearing system, bearing shells, bearings where viscous lubricants have to be used, bearings that are exposed to contamination (e.g., bearings on brackets), bearings of lead screws in slides, chain sprockets run loosely, rope sheaves, axle boxes, use of cold drawn round steel, bearing of shafts of dynamos, fans, centrifugal pumps
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Parts are movable into each other and have a small to large clearance.
Main bearings for crankshafts, guide crossheads, guide for piston rods, pistons in cylinder, bearings for gear wheel pumps, rope sheaves, bearings in internal combustion engines
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Parts are very easily movable into each other and have a very large clearance.
Transmission shafts and countershafts, plain bearings for rough and adverse conditions, secondary bearings for agricultural machinery, loose pulley, common bearings for locomotives, stuffing boxes, bearings in centrifuges, axle boxes for conveyances, general centralisations, spindles for textile machinery
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Parts have large clearance and large manufacturing tolerances.
Guides and plain bearings of secondary importance, heat-treated plain gearings (e.g., by liquids and gases), hinge pins and forked bolts, rivet pins, rivet joints, removable levers and cranks, socket wrenches, bad lubrication of parts, shafts for turbogenerators and continuous-flow machines, high-speed spindles for textile machinery, holes H11 (producible by using a twist drill that is guided in sleeves), use of cold finished round steel h11
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Parts with larger clearance and large manufacturing tolerances.
Secondary bearings for agricultural machinery and household appliances, pivot pins
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Parts with very large clearance and large manufacturing tolerances.
Secondary bearings in locomotive and railway carriage construction, hinges, bearings for agricultural and
construction machinery, door hinges, pivot pins, bearings that are exposed outside to elements
Click on the link ‘More calculation modules...’ and you will get to our web site. Here you find the free calculation modules as well as the possibility to register for a free test account to use also the other modules (e.g., the shaft calculation, the spur gear calculation, compression and tension spring calculation) (find more information in section 2 ‘The registration’).
Please note: With the registration for a free test account, you will get a password. You will need this password to login to the eAssistant. You get to the project manager. The windows ‘Calculation type’ enables you to start the free of charge modules. If you use these modules, no time will be subtract from you time account (find more information in section 3.7 ‘The time account’).
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 via telephone +49 (0) 531 129 399-0 or email eAssistant@gwj.de.
