5
ZDE 199 007 105 03/2013
2.1 Utilisation
JOST fifth wheel couplings are mechanical connecting devices and establish a connection between the
tractor and the semi-trailer. They are designed for mounting on a tractor unit.
Fifth wheel couplings, mounting plates and kingpins are vehicle-connecting parts that must comply with
very high safety requirements and must also undergo design approval tests.
Modifications of any kind will render both the warranty and the design approval void and therefore also
cancel the vehicle's operating licence.
JOST fifth wheel couplings are specified to comply with Directives 94/20/EC and Regulation ECE R55-01
in class 50 and are to be used only in conjunction with kingpins of class H50 and class J mounting plates
or comparable licensed equipment.
JOST fifth wheel couplings are suitable for use in power steering systems.
Technical modifications reserved.
The latest information can be found at: www.jost-world.com.
2.2 Specification
The fifth wheel coupling is specified with the vehicle by the vehicle manufacturer (the design must comply
with Directive 94/20/EC, Appendix VII or Regulation ECE R55-01 Appendix 7).
In addition to the fifth wheel load the D value is a criterion for the load capacity of fifth wheel couplings and
mounting plates.
It is calculated using the following formula:
D
= Drawing bar value [kN]
g
= 9.81 m/s
2
R
= Permissible total weight of the semi-trailer [t]
T
= Permissible total weight of the towing vehicle, including U [t]
U
= Permissible fifth wheel load [t]
Sample calculation:
T
= 17 t
R
= 33 t
U
= 10.5 t
2 Correct use
