CHAPTER 11
Basic Mechanical Design
11.1 Engineering abbreviations
Table 11.1 shows abbreviations that are in common use in engineering
drawings and specifications for rotating equipment.
Table 11.1 Engineering abbreviations
Abbreviation
Meaning
A/F
Across flats
ASSY
Assembly
CRS
Centres
L or CL
Centre line
CHAM
Chamfered
CSK
Countersunk
C’BORE
Counterbore
CYL
Cylinder or cylindrical
DIA
Diameter (in a note)
∅
Diameter (preceding a dimension)
DRG
Drawing
EXT
External
FIG.
Figure
HEX
Hexagon
INT
Internal
LH
Left hand
LG
Long
MATL
Material
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MAX
Maximum
MIN
Minimum
NO.
Number
PATT NO.
Pattern number
PCD
Pitch circle diameter
RAD
Radius (in a note)
R
Radius (preceding a dimension)
REQD
Required
RH
Right hand
SCR
Screwed
SH
Sheet
SK
Sketch
SPEC
Specification
SQ
Square (in a note)
Square (preceding a dimension)
STD
Standard
VOL
Volume
WT
Weight
11.2 American terminology
In the USA, slightly different terminology is used, see Table 11.2. These
abbreviations are based on the published standard ANSI/ASME Y14.5:
(1994) Dimensioning and tolerancing.
Table 11.2 American abbreviations
Abbreviation Meaning
ANSI
American National Standards Institute
ASA
American Standards Association
ASME
American Society of Mechanical Engineers
AVG
Average
CBORE
Counterbore
CDRILL
Counterdrill
CL
Centre line
CSK
Countersink
Table 11.1 Cont.
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277
FIM
Full indicator movement
FIR
Full indicator reading
GD&T
Geometric dimensioning and tolerancing
ISO
International Standards Organisation
LMC
Least material condition
MAX
Maximum
MDD
Master dimension definition
MDS
Master dimension surface
MIN
Minimum
mm
Millimetre
MMC
Maximum material condition
PORM
Plus or minus
R
Radius
REF
Reference
REQD
Required
RFS
Regardless of feature size
SEP REQT
Separate requirement
SI
Système International (the metric system)
SR
Spherical radius
SURF
Surface
THRU
Through
TIR
Total indicator reading
TOL
Tolerance
11.3 Preferred numbers and preferred sizes
Preferred numbers are derived from geometric series i