Design / features

JOST fifth wheel couplings fulfil the most stringent requirements in terms of safety, simple operation and ease of
servicing. This results in the following benefits:
Safety
High level of operating reliability
Can be used in complicated loading
conditions
Automatic latch arrangement
Only a visual inspection is required to
ensure proper engagement
Protection against unauthorised opening
is possible using a padlock

Ease of servicing
Infinite adjustment of the locking
mechanism, thus resulting in lower wear
Wearing ring is easy to replace
Easily replaceable top plate liners
Wearing parts can be replaced without
having to remove the fifth wheel

Fifth wheel couplings

and mounting plates

Simple operation
Long, easy-reach handle
The operator does not get dirty
The latch is released using a cable
JSK 42: Single hand operation without
latch and cable

Fifth wheel couplings are fitted to a tractor unit to

connect it to the trailer.
Fifth wheel couplings are vehicle attaching parts that
are subject to mandatory design approval and on
which the highest safety requirements are placed.
We can supply a suitable fifth wheel coupling for all
applications, thus always guaranteeing a safe and
secure link between the tractor and trailer.
When mounting, using, converting or exchanging
our fifth wheel couplings, the vehicle manufacturers
notes, JOST instructions for mounting and use, and
the relevant national regulations must be observed.
In Germany these are 19, 20, 21, 27 of the StVZO
Motor Vehicle Safety Standards.
The JSK 42 is available with a large selection of
pedestals in all common heights and with all
common hole patterns for plate and frame assembly.
Depending on the model and height, it is possible
to reduce the weight by 30 to 60 kg. This fifth-wheel
coupling is also exceptionally easy to operate: the
convenient handle enables you to release the lock
and open the JSK 42 with one hand.

Range of application
JOST fifth wheel couplings are approved for all trailer
coupling systems. The following diagram gives an overview
of the various models available with imposed loads from
6 t to 50 t.

Series
JSK 26
JSK 37 ME140
JSK 36 D
JSK 37
JSK 42
JSK 38-2"
JSK 38-3 1/2"
JSK 50

30

Imposed load (t)

6
15
20
28
36
50

Fifth wheel couplings and mounting plates

Fitting and component parts

The illustrations shows the basic design of a JOST fifth
wheel coupling.

Fifth wheel couplings are connection devices for use on

tractor units. An automatically closing and locking hitch
connects the fifth wheel king pin of the semitrailer when
coupling it up with the tractor unit.
The automatic latch arrangement locks the handle in
place and indicates that the tractor and trailer are correctly
attached.

Pedestal

Latch
Hole for
padlock

Long handle
with cable

Standard handle

B
C

Plate

Wearing
ring

An additional lock is integrated into the handle of the JSK 42.

This allows you to release the lock and open the handle with
one hand (convenient handle).
Open handle function JSK 42

Lock jaw
A

Wearing ring with plastic insert: for the JSK 37 E,

JSK 37 EW, JSK 37 CW and JSK 42 series.
Adjusting screw
for wear compensation

Wearing ring with plastic insert

Retainer for
wearing ring
Plastic
wearing ring

Lock jaw
Locking bar
Steel wearing ring: for the JSK 37 C, JSK 36 DV, JSK 38
and JSK 50 series.
Steel wearing ring
Standard handle

Handle extension
available as a spare part

31

Fifth wheel couplings and mounting plates

When choosing a fifth wheel coupling, you should especially

take into consideration the requirements placed on bearing
arrangements, mounting and maintenance. Basically, Jost
fifth wheel couplings can be used universally.

Cardan mounting Model G

Wear-resistant
bushing

Rubber bearing Model C

Shock-absorbing
rubber block

The cardanic bearing is designed to allow roll between tractor

and semi-trailer under off-road conditions. The lateral suspension can be disabled for on-road use.

Fifth wheel couplings with rubber mountings are particularly

suitable for poor quality road surfaces. The rubber cushions
are shock-absorbent and maintenance-free.

Prepared for central lubrication systems

Model E, K and all models with Z style

Lock jaw Z

Lubrication tube
for lock jaw
Lubrication tube
for wearing ring

Pivot bearing Model D, E and K

Collar (only "E" and "K" models)

Rubber
bushing

M8 x 1 (4x)

Pivot pin

The pivot bearing allows for low mounting heights and is

maintenance-free in the "E" and "K" version. They are especially well suited to use in sliding and dual-height fifth wheel
systems. Model K: protects the chassis dues to its longitudinal elasticity (lateral movement).

32

Fifth wheel couplings need to be lubricated (manual lubrication). Model E, K and all models with Z style fifth
wheel couplings are prepared for connection to a central lubrication system on the tractor unit.
W series fifth wheel couplings (with top-plate liners) are low
maintenance, i.e. only the lock needs to be lubricated. For
details, see the installation and operating instructions.

Fifth wheel couplings and mounting plates

Plate mounting

Chassis mounting

Fifth wheel coupling

Fifth wheel coupling
with mounting angle
Mounting plate
Vehicle chassis
Vehicle chassis

The fifth wheel coupling is fixed to the tractor chassis by

means of a mounting plate. Various mounting plate and fifth
wheel mounting heights are available to make an accurate
match between the height of the fifth wheel and existing
trailer systems possible.
JOST mounting plates for fifth wheel couplings satisfy the
requirements of Directive 94/20/EC Class J and are
approved for the steering forces of steered semi-trailers. We
also offer a selection of mounting kits for connecting
mounting plates and fifth wheels to the tractor unit.

The fifth wheel coupling is built onto either the chassis or

sub-frame of the tractor.
The JOST mounting instructions for fifth wheel couplings and
mounting plates, as well as the respective mounting instructions supplied by the vehicle manufacturer must be observed
when mounting or converting equipment.

Low-maintenance JOST fifth wheel coupling W Style

The series JSK 37 CW/EW fifth wheel couplings and all
the series JSK 42 fifth wheel couplings in version W are
equipped with a top plate liner on the mounting surface and
a wearing ring with plastic insert in the locking mechanism.
In conjunction with the maintenance-free rubber or pivot

bearing, only one greasing point on the lock jaw needs local
lubrication. All wearing parts can be replaced quickly and easily. Low-maintenance fifth wheel couplings therefore
save both time and money, as well as conserving resources.

Wearing ring

Top plate liner

Retainer for
wearing ring
Plastic
wearing ring

Lubrication tube
for lock jaw

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Fifth wheel couplings and mounting plates

Type designation
The fifth wheel type plate is secured on the side of the
coupling plate. When ordering spare parts, please quote the
model designation and the serial number.

EU approval numbers
Maximum load data
SK 3105-124-02

Sattelkupplung
Sellette
Fifth wheel coupling

EG e1

00-0116

G 50-X D 152

U 20

D
Neu-Isenburg, Germany / R.F.A.

Artikelnr.
Type
Part no.
Ausf.bez.

E
Order No.: XXX XXXXX Nr.
N
JSK 37C150ZJ

Version
designation or
order number

04 28 12 4444

Order number

Vor Benutzung Betriebsanleitung lesen.

Voir Notice dnstructions avant utilisation.
Read operating manual before use.

National
approval
numbers
(optional)

Serial number

Definition D value
The construction of the fifth wheel coupling in connection
with the vehicle is carried out by the vehicle manufacturer
(construction according to Directive 94/20/EC, Appendix VII).
The imposed load on the tractor and the D value are
criterions for the load-bearing capacity of the fifth wheel
couplings and mounting plates.
The D value calculates according to the following formula:
D=gx
Key:
T =
R =
U =
g =

0,6 x T x R
(kN)
T+R-U

permissible total weight of the tractor unit in t

(including U)
permissible total weight of the semi-trailer in t
permissible imposed load on tractor in t
9,81m / sec2

Calculation example:
D = 9,81 x

34

0,6 x 17 x 33
= 83,6 (kN)
17 + 33 - 10,5

Given:T = 17t
R = 33t
U = 10,5t

The permissible load data for JOST fifth wheel couplings

can be found on the type plate or from the JOST product
catalogue. They apply for the intended use in compliance
with the Directive 94 / 20 EC or ECE-R55. If additional
dynamic demands are to be placed on the coupling, e.g. by
use on uneven road surfaces or building sites, the imposed
load and D value should not be fully used or a stronger fifth
wheel coupling should be fitted, and/or you should ask JOST
for advice.

Fifth wheel couplings and mounting plates

Product overview
The table below shows the standard versions
dependent on load, bearing and maintenance.
Other models are available on request.

Series
JSK 26D
JSK 36 DA*
JSK 36 DV
JSK 37 C
JSK 37 CW
JSK 37 CZ
JSK 37 E
JSK 37 EW
JSK 37 EA*
JSK 37 EAW*
JSK 37 ER*
JSK 37 ERW*
JSK 37 ME140
JSK 37 ME140W
JSK 42 K0*
JSK 42 K2-K6*
JSK 42 K7*
JSK 42 K8*
JSK 42 MK 162
JSK 38 C-1
JSK 38 C-1 2
JSK 38 G-1
JSK 38 G-1 2
JSK 38 MC
JSK 50

Lock
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3 1/2
2
3 1/2
2
3 1/2
3 1/2

D value
(kN)
50.0
152.0
152.0
152.0
152.0
152.0
152.0
152.0
152.0
152.0
152.0
152.0
126.0
126.0
152.0
152.0
152.0
152.0
152.0
260.0
170.0
260.0
170.0
260.0
300.0

Imposed load
U (t)
6
20
20
20
20
20
20
20
20
20
20
20
15
15
20
20
20
20
20
36
28
36
28
36
50

Explanations:
X = Bearing design
M = Manual lubrication
Z = Prepared for connection to the central lubrication
system on the tractor unit

Rubber
bearing

Slide
bearing
X
X
X

Cardan
bearing

X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X

M, Z =
W

Maintenance
M
M
M
M
W
Z
Z
W
Z
W
Z
W
Z
W
Z, W
Z, W
Z, W
Z, W
Z, W
M, Z
M, Z
M, Z
M, Z
M, Z
M

Available either for manual lubrication or prepared

for central lubrication
Low-maintenance, lubrication only required on the
lock jaw
Chassis mounting
Before you use this fifth wheel coupling you must
obtain approval from the tractor unit manufacturer

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