BRITISH STANDARD AUTOMOBILE SERIES BS AU 226 1988 ISO 7648 1987 Specification for Nominal dimensions and tolerances of flywheel housings for reciprocating internal combustion engines [ISO title Flywhe[.]
BRITISH STANDARD AUTOMOBILE SERIES Specification for Nominal dimensions and tolerances of flywheel housings for reciprocating internal combustion engines [ISO title: Flywheel housings for reciprocating internal combustion engines — Nominal dimensions and tolerances] UDC 629 1 3/ 5: [62 – 21 – 562 (083 3)] BS AU 226:1988 ISO 7648:1987 BS AU 226:1988 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Automobile Standards Committee (AUE/- ) to Technical Committee AUE/1 3, upon which the following bodies were represented: Department of Transport (Highways) Freight Transport Association Institute of Road Transport Engineers (Incorporated) London Regional Transport Ministry of Defence National Bus Company Road Haulage Association Ltd Society of Motor Manufacturers and Traders Limited This British Standard, having been prepared under the direction of the Automobile Standards Committee, was published under the authority of Board of BSI and comes into effect on 31 August 988 © BSI 02- 2000 The following BSI references relate to the work on this standard: Committee reference AUE/1 Draft for comment 82/79772 DC ISBN 580 16727 Amendments issued since publication Amd No Date of issue Comments BS AU 226:1988 Contents Page C ommittees res p ons ib le Ins ide front cover National foreword ii S cop e and field of ap p lication References Nominal dimens ions and tolerances Relations hip of p ilot b earing b ore to flywheel hous ing Mating p art flange Annex Procedure for measuring b ore eccentricity and face deviation Figure — Flywheel hous ing Figure — Bolt or s crew hole s p acing Figure — D ep th of p ilot b earing b ore Figure — Res ultant total indicator reading, I R Tab le — Flywheel hous ing dimensions and tolerances Tab le — Tap p ed holes and b olt or s crew sp acing and dimens ions Tab le — D ep th of p ilot b earing b ore Tab le — D ata chart Pub lications referred to © BS I - 00 Ins ide b ack cover i BS AU 226:1 988 National foreword This British Standard has been prepared under the direction of the Automobile Flywheel housings for reciprocating internal combustion engines — Nominal dimensions and tolerances”, published by the International Organization for Standardization Standards Committee and is identical with ISO 7648: 987 “ (ISO) Terminology and conventions The text of the International Standard has been approved as suitable for publication as a British Standard without deviation Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following The comma has been used as a decimal marker In British Standards it is current practice to use a full point on the baseline as the decimal marker Wherever the words “International Standard” appear, referring to this standard, they should be read as “British Standard” Cross-references International Standard ISO 273: 979 Corresponding British Standard Specification for clearance holes for metric bolts and screws BS 41 86: 984 (Identical) The Technical Committee has reviewed the provisions of ISO 1 01 and ISO 7649, to which reference is made in the text, and has decided that they are acceptable for use in conj unction with this standard A related British Standard to ISO 1 01 is BS 308 “ Engineering drawing practice” Part “Geometrical tolerancing” A British Standard does not purport to include all the necessary provisions of a contract Users of British Standards are responsible for their correct application Compliance with a British Standard does not of itself confer immunity from legal obligations Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages to 8, an inside back cover and a back cover This standard has been updated (see copyright date) and may have had amendments incorporated This will be indicated in the amendment table on the inside front cover ii © BSI 02- 2000 BS AU 226:1 988 Scope and field of application This International Standard specifies the nominal dimensions and tolerances of flywheel housings for reciprocating internal combustion engines, in particular those which affect inter- changeability with mating parts It applies to reciprocating internal combustion engines except engines for aircraft and passenger cars Flywheel housings of size codes to are recommended for commercial vehicles and buses References ISO 273, Fasteners — Clearance ho les for b olts and s crew s ISO 1 01 , Technical draw ings — Geom etrical tolerancing — Tolerancing of form , orientation, location and run- out — Generalities , ISO 7649, definitions, sym b ols, indications on draw ings Com m ercial v ehicles — Clutch housings for internal com b ustion engines — No m inal dim ensio ns and tolerances 1) Nominal dimensions and tolerances 3.1 Flywheel housing See Figure and Table Table — Flywheel housing dimensions and tolerances Dimensions in millimetres Run-out A Size code nom 01 0, 00 01 +0, 25 787, 40 00 B t nom tol +0, 25 245 02 (assembled flywheel housing) +0, 25 a D 400 10 1 65 10 0, 47 883 0, 39 71 0, 35 648 0, 31 553 0, 27 489 0, 25 45 0, 25 404 0, 25 35 0, 25 308 not applicable 647, 70 +0, 25 /2 584, 20 +0, 20 51 , +0, 0 447, 68 +0, 409, 58 +0, 361 , 95 +0, 31 4, 32 +0, 0 266, 70 +0, NOTE Run- out tolerances t shall be measured on the assembled engine mounted on its supports in accordance with the annex (See ISO 1 01 for definition of run- out ) a Dimension D relates to flywheel housings without rubber sealing However, this dimension may be increased if a rubber seal is necessary 1) At present at the stage of draft © BSI 02- 2000 BS AU 2 6: 988 Figure — Flyw he e l ho using Bolt o r scre w sp acing and siz e 3.2.1 Dimensions and tolerances See Figure and Table Tab le — Tap p e d ho le s and b o lt o r scre w sp acing and dime nsions S iz e co d e Tap p e d ho le s C Re co mme nd e d thre ad nom e ngage me nt 16 M1 /2 12 M1 12 M1 12 M1 12 M1 12 M1 M1 M1 NOTE a nom of bolt or screw M1 1 05, 00 ×? 16 340, 00 00 For aluminium flywheel housing M1 nom of bolt or screw M1 24 ×? 24 01 (see Figure and Figure 2) For cast iron flywheel housing 02 a mm Size 1,5 Number 850, 90 679, 45 61 9, 530, 466, 72 428, 62 381 , 00 333, 38 285, 75 24 tapped holes are optional for aluminium flywheel housings of size code M1 may be used for high engine torque applications © BSI 02- 2000 BS AU 226:1 988 3.2.2 Spacing Tapped holes shall be spaced equally on each side of the vertical and horizontal axis lines as shown in Figure Figure — Bolt or screw hole spacing Relationship of pilot bearing bore to flywheel housing The depth of the pilot bearing bore (see E in Figure 3) extends from the flywheel housing face to a shoulder in the flywheel, to a shoulder within the crankshaft or to the crankshaft flange face Table — Depth of pilot bearing bore Dimensions in millimetres E Size code nom E nom optional for: double plate clutches when overcentre clutch extra-heavy flywheel is used 02 265 — — 01 265 — — 00 00 33, — 00 33, — /2 00 33, — 1 00 – 1 33, — 00 – 1 a — — 00 — — 00 — 71 71 — 00 71 — — a An a E dimension of 1 mm is optional for flywheel housing size codes and when the clutch shaft bearing is located in the pilot bearing bore of the flywheel or crankshaft end, i e when the bearing is not located in a separate carrier © BSI 02- 2000 BS AU 2 6: 988 Figure — D e p th o f p ilot b e aring b o re Mating p art flange (for example, clutch housings) The dimensions and tolerances of clutch housings for reciprocating internal combustion engines are given in ISO 7649 Limits and fits of the pilot diameter of the mating part are at the discretion of the manufacturer of that component The manufacturer shall also specify the tolerances of form and position of the mating part flange The clearance holes of the mating part flange shall have the same location as specified under 3.2.2 and shall be in accordance with ISO 273 © BSI 02- 2000 BS AU 2 6: 988 Annex Proce dure for me asuring b ore ecce ntricity and face de viation (This annex forms an integral part of the Standard ) A S co p e This annex provides a uniform procedure for measuring bore eccentricity and face deviation (run- out) of flywheel housings after assembly to an engine Limits of bore eccentricity and face deviation are given in Table A Me asuring p ro ce dure s A General A A dial indicator with rigid extension bars is required A Surfaces which are to be measured shall be free from dirt and burrs A Prepare a chart as shown in Table to help in determining bore eccentricity A Eccentricity of housing A Mount the indicator base on the flywheel or crankshaft flange as close as possible to the housing pilot bore to minimize deflection A Adj ust the indicator point to be perpendicular to the housing pilot bore and set at zero in the o ½ clock (mandatory) position (lower vertical) A Slowly rotate the crankshaft and record the indicator reading along with the appropriate positive or negative sign at the o ½ clock (a), o ½ clock (b), and o ½ clock (c) locations Confirm that the o ½ clock reading is still zero Record the readings on line A in Table 4, being sure to include the positive or negative sign Tab le — D ata chart D e signatio n o ½ clo ck o ½ clo ck A Observed indicator reading a= B Adj ustment for bearing clearance — — C Half- bearing clearance adj ustment — D Total corrected vertical indicator reading I E Corrected horizontal indicator reading — F Total horizontal indicator reading I =b+d E = a + d/2 E = c + d/2 I =E –E v I H d/2 = = E = o ½ clo ck b= d= o ½ clo ck c= — — d/2 = — E = V H I = R ( I) v + ( I H ) 2 CAUTION — Sign designation relative to direction of indicator tip movement is not the same for all indicators For all measurements in the calculations carried out in accordance with A , outward movement of the indicator tip with respect to the centre of the bore being measured is to be considered a negative reading © BSI 02- 2000 BS AU 2 6: 988 Figure — Re sultant total indicator reading, A Position the indicator at the o ½ clock location and determine I R d, the adj ustment for clearance in the main bearing adj acent to the flywheel, by an appropriate method, for example by raising the crankshaft to its upper limit Record the adj ustment for bearing clearance on line B in Table in the o ½ clock column This value shall always be positive NOTE A floor- mounted support with a padded prybar or other suitable means can be used to raise the flywheel; however it should not be forced beyond the point where the bearing clearance has been removed, nor should the housing be used as a fulcrum A Correct the o ½ clock reading obtained in A bearing clearance to it I ) Record this value on line D in Table This is the corrected total vertical indicator reading ( A by algebraically adding the adj ustment for V Correct the o ½ clock and o ½ clock readings from A to one- half of the adj ustment for bearing clearance determined in by taking the clearance adj ustment determined in A , by algebraically adding an amount equal A to each of them This can be done dividing it by two, and entering it on line C in the o ½ clock and o ½ clock columns Again, this value will always be positive The readings, corrected for bearing clearance, can then be obtained by algebraically summing the values in lines A and C of the o ½ clock and o ½ clock columns These values shall be denoted as Table A I H = and E and entered on line E in I ) by taking the algebraic difference between the E – E ) This value is to be entered on line F in Table Determine the horizontal indicator reading ( corrected o ½ clock and o ½ clock readings ( E H © BSI 02- 2000 BS AU 2 6: 988 A Determine the resultant total indicator reading (IR ) of the housing or adapter by locating the intersection point of the total vertical indicator reading (IV) and the total horizontal indicator reading (IH ) in Figure 4, or calculate as follows: IR = NOTE Ỉ (Iv) + (IH ) This value (IR) is consistent with a total indicator type reading as are the limits specified in Table It is not eccentricity as such Actual eccentricity is equal to one- half of this value A Face deviaton of housing A Mount the indicator base in accordance with A A Adj ust the indicator point to be perpendicular to the face A After eliminating the crankshaft end play, e g , by tilting the crankshaft or by inclining the engine approximately ° to 20 ° , set the dial indicator to zero in the o ½ clock (not mandatory) position A Taking care to keep the end play eliminated in the same direction as in the o ½ clock position, rotate the crankshaft one complete revolution to determine the total indicator reading A Compare the total indicator reading with the limit specified in Table © BSI 02- 2000 blank BS AU 226:1988 Publications referred to See national foreword © BSI 02 - 000 BS AU 226:1988 ISO 7648:1987 BSI — British Standards Institution BS I is the indep endent national b ody res p ons ib le for p rep 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