ISO 1726-2:2007

INTERNATIONAL ISO
STANDARD 1726-2
First edition
2007-04-15

Road vehicles — Mechanical couplings
between tractors and semi-trailers —
Part 2:
Interchangeability between low-coupling
tractors and high-volume semi-trailers
Véhicules routiers — Liaisons mécaniques entre tracteurs et semi-
remorques —
Partie 2: Interchangeabilité entre tracteurs avec accouplement bas et
semi-remorques de grand volume



Reference number
ISO 1726-2:2007(E)
©
ISO 2007

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ISO 1726-2:2007(E)
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ISO 1726-2:2007(E)
Foreword
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ISO 1726-2 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 15,
Interchangeability of components of commercial vehicles and buses.
ISO 1726 consists of the following parts, under the general title Road vehicles — Mechanical couplings
between tractors and semi-trailers:
1)
⎯ Part 1: Interchangeability between tractors and semi-trailers for general cargo
⎯ Part 2: Interchangeability between low-coupling tractors and high-volume semi-trailers


1) Revision of ISO 1726:2000.
© ISO 2007 – All rights reserved iii

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INTERNATIONAL STANDARD ISO 1726-2:2007(E)

Road vehicles — Mechanical couplings between tractors and
semi-trailers —
Part 2:
Interchangeability between low-coupling tractors and
high-volume semi-trailers
1 Scope
This part of ISO 1726 specifies dimensions to ensure interchangeability between a low coupling height tractor
vehicle and a coupled high-volume semi-trailer, the two together constituting a high-volume articulated vehicle.
It specifies certain interchangeability dimensions, including those of the optimised gooseneck contour, as well
as operating dimensions related to angle values. The specifications are primarily intended to permit
semi-trailers to be coupled with two-axle tractors. However, three-axle tractors are not excluded, provided they
are in compliance with the requirements of this part of ISO 1726.
This part of ISO 1726 does not provide limitations of maximum gross mass and overall dimensions, which are
generally laid down by legislative requirements.
2 Interchangeability dimensions
2.1 Height of fifth wheel of a laden tractor
The height, h, of the fifth wheel of a laden low-coupling tractor above ground (see Figure 1) shall be in the
range 900 mm to 975 mm.

Key
h height of fifth wheel
Figure 1 — Height of fifth wheel
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ISO 1726-2:2007(E)
2.2 Height of fifth wheel of an uncoupled tractor
The height, h, of the fifth wheel of an uncoupled low-coupling tractor shall not exceed 1 000 mm.
2.3 Forward clearance zone radius of a semi-trailer
The front end of the semi-trailer (see Figure 2) shall not exceed the radius, r , of 2 040 mm.
1
Dimensions in millimetres

Key
L distance between two cylinders of revolution [see 3.4 a)]
4
L distance between surface of cylinder of revolution and conical surface of revolution [see 3.4 b)]
5
r forward clearance zone radius of semi-trailer (see 2.3)
1
r radius between axis of coupling pin and lower part of the semi-trailer gooseneck [see 2.4 d)]
3
ω angle of inclination towards the front
1
ω angle of inclination towards the rear
2
ϕ angle of articulation
Figure 2 — Free space between tractor and semi-trailer
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ISO 1726-2:2007(E)
2.4 Gooseneck contour
The gooseneck shall be located on the outside of a surface consisting of different planes and one surface of
revolution
...