5
1 Product Description
1.1 Construction
Fig.1.3: Timing belt / pulley relationship
Fig.1.2: Double section timing belt
Section
Overall
belt
thickness
h
s1
(mm)
Tooth
angle
2 β
(°)
Tooth
depth
h
t
(mm)
Tooth
width
at top
b
(mm
)
Tooth
pitch
t
(mm)
Overall
belt
thickness
h
s
(mm
)
Tooth
width
at base
s
(mm)
Table 1.1: Section dimensions, sections see Fig. 1.5, page 8,
Standards see Table 5.6, page 48
MXL 2.032 1.14 — 0.51 1.14 — 40
XL 5.080 2.30 — 1.27 2.57 — 50
L 9.525 3.60 — 1.91 4.65 — 40
H 12.700 4.30 — 2.29 6.12 — 40
XH 22.225 11.20 — 6.35 12.57 — 40
T2.5 2.500 1.30 — 0.70 1.50 — 40
T5 5.000 2.20 — 1.20 2.65 — 40
T5D 5.000 — 3.4 1.20 2.65 — 40
T10 10.000 4.50 — 2.50 5.30 — 40
T10D 10.000 — 7.0 2.50 5.30 — 40
T20 20.000 8.00 — 5.00 10.15 — 40
T20D 20.000 — 13.0 5.00 10.15 — 40
AT5 5.000 2.70 — 1.20 — 2.50 50
AT10 10.000 5.00 — 2.50 — 5.00 50
AT20 20.000 9.00 — 5.00 — 10.00 50
5M 5.000 3.60 — 2.10 — — —
8M 8.000 5.60 — 3.38 — — —
14M 14.000 10.00 — 6.10 — — —
The tooth pitch ‘t’ is the distance between two corresponding points
on adjacent teeth on either the belt or the pulley effective diameter.
When the timing belt is laid flat the tooth pitch ‘t’ can be measured
from tooth centre to centre.
When the belt is bent around a pulley the tooth pitch ‘t’ is measured
at the level of the tension cord, also called the effective radius. The
effective diameter ‘d
d
’ thus describes a circle which lies outside the
perimeter of the pulley (d
d
> d
a
).
Construction of the double section timing belt
The construction of the double section timing belt is similar to the
normal timing belt already described. The number and spacing of
the teeth are identical on both sides of the belt, but the two sides
are offset to each other (see Fig. 1.2).
The tension cord and its position relative to the base and teeth are
the same. The maximum permitted power of the double section
timing belt is therefore not doubled but is the same as for the
corresponding normal belt. The power can be transmitted by both
sides of the belt as required.
Base
Tooth
Tooth
Base
Tension cord
d
a
d
w
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