BS AU 226:1988 download.Specification for Nominal dimensions and tolerances of flywheel housings for reciprocating internal combustion engines.
1 Scope and field of application
BS AU 226 specifies the nommal dimensions and tolerances of flywheel housings fbr 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 I to 4 are recommended for commercial vehicles and buses.
2 References
Iso 273, Fasteners — Clearance holes for bolts and screws.
Iso 1101, Technical drawings — Geometrical tokrancing — Tolerancing of form, orientation, locahon and
run-out — Generalities, definitions, symbols, indications on drawings.
ISO 7649, Commercial vehicles — Ulutch housings for internal corn bU8tion engines — Nominal dimensions and tolerances .
3 Nominal dimensions and tolerances
3.1 Flywheel housing
See Figure 1 and Table 1.
3.2 Bolt or screw spacing and size
3.2.1 Dimensions and tolerances
See Figure 1 and Table 2
3.2.2 Spacing
Tapped holes shall be spaced equally on each side of the vertical and horirnntal axis lines a shown in Figure 2.
4 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.
5 Mating part 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.