1. AN INSIGHT Presented by- ADRIMA BORUAH BEDANTA BORTHAKUR CHABIN CHETIA
FIFTH WHEEL COUPLING
AN INSIGHT
Presented by-
ADRIMA BORUAH
BEDANTA BORTHAKUR
CHABIN CHETIA

2. Articulated vehicle
An articulated vehicle is a vehicle which has a permanent or semi-permanent pivoting joint in its construction, allowing the vehicle to turn more sharply.
Some of the types of articulated vehicles:
a) Semi Trailer Trucks
b) Articulated Buses
c) Articulated Agricultural &
Forestry Tractors

3. Trailer A trailer is an unpowered unit pulled by a powered unit.
The powered unit is known as Prime mover.
Trailers are of two types –
a) Full Trailer b) Semi Trailer

4. Difference between a Full Trailer & a Semi-Trailer
A Full Trailer supports the pay load on it own. The prime mover only provides the tractive effort required to give it motion.
Whereas in case of a Semi Trailer, the prime mover provides the tractive effort and also supports a part of the vertical load on the Semi Trailer bed.

5. Types of Semi-trailer
Types of Semi-trailers designed to haul different cargos:
a) Flat Bed Semi Trailer- Consists of just a load floor. It can haul almost anything that can be stacked on and strapped down.
b) Low Bed Semi Trailer- Type of flatbed in which the load floor is as close to the ground as possible. Most commonly used to haul heavy equipment, cranes, bulldozers, etc.
c) Semi Low Bed Semi Trailer – The height of the load floor is somewhat higher than that of a Low bed one.
Two or more trailers hauled by a single prime mover is generally called a Road Train.

6. A Road Train

7. Fifth wheel coupling
The fifth wheel coupling provides the link between a prime mover and a semi-trailer.
The coupling consists of a coupling pin (or king pin) on the front of the semi-trailer and a horseshoe-shaped coupling device called a fifth wheel coupling on the rear top of the prime-mover.
The contact surface of the Semi trailer with the fifth wheel is known as the Rubbing Plate.
The term fifth wheel comes from a similar coupling used on four-wheel horse-drawn carriages and wagons in the past.

8. Types of Kingpin based on mounting arrangement
Retention plates with cone shaped locating hole.
Dish shaped retention plates.
Flat retention plates.

9. Some of the components of Fifth Wheel Coupling
Handle
Lock Jaw
Locking Bar
Springs
Wearing/Cushion Ring
Pivot Bracket
Mounting Feet

10. Wearing/Cushion Ring Wearing/Cushion ring absorbs kingpin impacts.
Reduces king pin and lock wear.

11. Pivot Bracket
Fifth wheel couplings are provided with pivot brackets having rubber bushing for shock-absorption.
These are particularly suitable for poor quality road surfaces and are maintenance-free.

12. Mounting Feet
Mounting Feet is the pedestal on which the Fifth Wheel rests.
Three types of mounting feet are generally available in our vehicles.
They are :
a) Outboard Flat Plate
b) Outboard Plate Mount
c) Inboard Angle Mount

13. Outboard Flat Plate Outboard Plate Mount
Inboard Angle Mount

14. Locking mechanism

16. Illustration of Locking Mechanism
Video depicting the operation of the Fifth Wheel locking
mechanism.
fifthwheel video1.wmv

17. Selection of a Fifth Wheel coupling & a Kingpin
Fifth Wheel & Kingpin, being a critical component of a tractor-trailer, are designed as per various standards. One of the prime factors of designing is D-value (i.e. Drawbar Value).

18. The Drawbar Value
Definition: It is the horizontal force between the tractor and trailer loaded to maximum capacity.
It is conventionally marked in the lower flange of the Kingpin.
In order to confirm the suitability of a particular fifth wheel or a king pin for a given tractor-trailer combination it is necessary to carry out a D-Value calculation.
The unit of D-Value is KN.

19. Calculation of D-Value
The required D-Value for Fifth Wheel Equipment is determined by the
following formula :
D = g x 0.6 x T x R KN (9.81 Kgf=1 N)
T + R – U
where
T is the maximum design total mass, including U, of the towing vehicle which is to tow the semi-trailer, in tonnes:
U is the mass imposed vertically on the fifth wheel coupling by the semi-trailer loaded to its maximum design total mass, in tonnes;
R is the maximum design total mass of the semi-trailer which is to be drawn with the fifth wheel, in tonnes;
g is the acceleration due to gravity (= 9.81 m/s²).

20. R= Payload of the trailer + Self weight of the trailer
U= R - Load on the rear axle of the trailer
T= Weight of the prime mover + U

21. D-Value of a 49 MT GCW Tractor-Trailer unit
The formula is: D = g x 0.6 x T x R
T + R – U
Let us assume,
Wt. of Prime Mover= 6 MT
Wt. of the Trailer= 9 MT
Payload capacity of Trailer= 30 MT
Rated load on the rear axle= 24 MT
Based on this, the following values were calculated –
R= 30+9= 39 MT
U= = 15 MT
T= 6+15= 21 MT
۪ ˚ ۪ D = 9.81 x 0.6 x 39 x 21
– 15
= KN

22. Product Overview Table of JOST

23. BIS Specifications For Fifth Wheel Couplings.
Conventionally king pins are available in sizes –
2” (50 mm) &
3.5” (90 mm)
IS 6763 (part-1):1987 & IS 6763 (part-2):1987
specifies the dimensions & testing procedures of kingpin sizes 2” & 3.5” respectively.
IS: specifies dimensions concerning a transport tractor and a coupled semi-trailer ( articulated trailer ) which allow interchangeability.
IS 15101:2002 specifies test conditions and strength requirements to be met by 50 and 90 mm fifth wheel couplings.

32. IS 15101:2002

33. IS :

35. Recommendations for Safe Operation
Video depicting safe coupling sequence
fifth wheel\fifthwheel video 2.wmv
These days new technologies are also being developed to ensure safer operation, such as Sensor Controlled Fifth Wheel Coupling.

36. Sensor Controlled Fifth Wheel Coupling
The Sensor Coupling System available for modern fifth wheel couplings makes coupling and uncoupling safe and convenient due to electronic monitoring and a pneumatic remote control.
Three sensors monitor the system. The first sensor provides information about the correct coupling height and automatically activates the system during coupling.
The second sensor checks the position of the king pin, and the third one monitors the locking status.
All of the functions are controlled via a central operating module in the driver’s cab. Illuminated symbols offer the driver clear information about the locking status of the fifth wheel coupling, reliably preventing coupling errors.
Uncoupling can be done via a pneumatic remote control system from the driver’s cabin itself.

37. Conclusion Implication of the D-Values calculated in the example :
The D-Values calculated provide us an idea about the suitability of a particular fifth wheel or kingpin for a given tractor/trailer combination while taking purchasing/replacing decisions.
The Fifth Wheel Coupling chosen should be as per the D-Value. Under no circumstances should a coupling with lower D-Value be selected.
All safety practices as shown in the video should be followed to avoid any untoward incident.
The insights gained will also help us in identifying the specifications that need to be included in formulating indents for new purchases/spares.