TYPES OF COUPLING SYSTEMS USED BY "INDIAN RAILWAYS"

TYPES OF COUPLING SYSTEMS USED BY "INDIAN RAILWAYS" (BROAD GUAGE)

DRAW AND BUFFING GEAR ASSEMBLY

Draw and buffing gears are attached to the end of one  coach and this two gear mechanisms are made to suit two adjacent coaches into an uniform continuous movement. They also transform the hauling force from main engine to the following rake, draw gear is specialized for these purpose, where as the buffing gears are essential for maintaining a vibration less motion of a coach with respect to its former one.

                       

We have two different arrangements of draw and buffing gear assembly in ICF and LHB coaches. They are-

FOR "CONVENTIONAL" ICF TYPE COACHES

SCREW COUPLER IN ICF COACHES

Screw coupling and the side buffers serves the aforesaid purpose in case of the draw and buffing gears respectively in case of ICF coaches. Screw coupling not only gives the boost but also let two coaches to connect in the formation of a continuous rake. The two jaws of the screw on both sides are guarded with spring and rubber to minimize the vibration the hauling force produces. They are called the DRAFT GEARS.

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Side buffers are uniquely shaped buffers. They have a flat plate made of stainless steel and duly lubricated in contact to each other facing each other in motion. They are also guarded with the iron plated and spring and rubber to minimize the vibration as much as possible.

FOR LHB TYPE COACHES

CBC TYPE COUPLER FOR LHB COACHES

For LHB coaches we have a multipurpose serving coupling between the two coaches. It is called in technical terms the Center Buffer Coupling.  It has got a special locking system operated by a handle.

A CBC COUPLER AT DISPLAY (RCF)

‘H’ TYPE CBC COUPLER :

Coupler:

Ø The coupler provides a means of mechanically connecting individual adjacent vehicles in order to make a train.

Ø The couplers are located at both end of each vehicle.

Ø When connected with a coupler of an adjacent vehicle it allows the vehicle to move independently to accommodate track curvature and elevation change while remaining connected together.

“H” Type Tight Lock Coupler:

Ø The AAR “H” type tight lock couplers are used in LHB/ HYBRID coaches instead of screw coupler.

Ø The coupler is opened manually using the coupler operating rod and is closed automatically when the couplers on adjacent vehicle are mated.

Ø The coupler automatically locks when fully mated. 

Main Parts Of “H”type CBC:

1.“H” Type Tight Lock Coupler Head.
2. Draft Gear.
3. Supporting Device.
4. Manual Uncoupling Device

DRAFT GEAR

The Draft Gear is a double acting device for energy absorption during coupling and services.

The device is designed to fit into the draft gear pocket of
the Coach and absorb the dynamic energy in both i.e.
draw and buff modes.

SUPPORTING DEVICE

Supporting device comprises of four preloaded
springs. It is placed on a platform and bolted
to the car structure. The coupler head rests on the top wear plate of the supporting device and this device supports the coupler weight.
Its main parts are- Wear plate, Frame,
Compression spring, Nut & Bolts.

Advantages of CBC:

Ø High hauling capacity permits to attach more No. of coaches.

Ø Rake fitted with CBC can be run with comparatively high speed.

Ø No need to provide separate Buffing Gears. Hence the incidence of Buffer interlocking is avoided.

Ø Coupling/Uncoupling can be done easily from track side.

TECHNICAL DATA:

Ø Draft Gear capacity:

- Dynamic energy absorption capacity: 45 k J (min).

 - End force : 1600 kN (max)

Ø Stroke : Tension- 58 mm, Compression- 80mm.

                      - Pre load : 30 k N

Ø Strength of Coupler Head with Draft Gear :

Tensile load = 1000 kN, Compressive load = 2000kN.

Bending test of Coupler head: 300kN.

Ø Coupler length : 1030 ± 5mm

Ø Weight of coupler : 500kg.

Ø Gathering range: Horizontal: ± 110mm, Vertical : ± 90mm.

Ø Maximum horizontal swing coupler : ± 17.85 °

Ø Maximum vertical swing coupler : ± 7 °

Ø The maximum slack is restricted to 3.5 mm 

SCHAKU COUPLER:

Originally designed by M/s Scharfenburgkupplung, GmbH, Germany are used on the EMU stock of  Indian Railways.

SCHAKU COUPLER USED IN EMU

In Semi permanent couplers the coupling is done manually and the two couplers after being aligned are secured by means of an adjustable cup sleeve joint. During the process of manual coupling the air pipe connections between the two coaches are also established automatically. The pivoted joints between the coupler and the coaches is designed and constructed in such a way that even in case of maximum difference in level, the coaches are capable of negotiating all track curves and of passing through points of change of gradient occurring during service. This coupler fulfills all other operational requirements.

 SALIENT FEATURES OF ESCORTS SEMI-PERMANENT

·        Semi-permanent coupler can take up a compressed load of 100 tons and tensile load of 70 tons.

·         The dynamic absorption capacity of the rubber draft gear of these couplers is 800 m-kg.

·         Due to rigid connection of this coupler there exists negligible play between them in coupling position and hence no appreciable wear and tear during train operation.

·         Due to rigid and stress transmitting mechanical connection between the coaches by fitting semi-permanent couplers, protection to the coach and the load against undue impacts is secured.

·         Due to high draft capacity incorporated in semi-permanent couplers, it allows coaches to buffer at higher speeds (from 3 km/hr to 15 km/hr) without any damage to the coach and the load.

·         The interlocking arrangement of these couplers prevents to some extent the mounting or telescoping of the coaches when involved in accidents.

·         As the fulcrum of these couplers is located far in the rear of the coach, coupler side displacements in curves and consequently the transverse forces acting on the wheel flanges are kept minimum .This reduces the wear of the wheel flanges and minimizes the chances of derailment.

·         As the coupling links of semi-permanent couplers form a parallelogram with equilibrium of forces, unintentional disengagement of coaches due to shocks is rendered impossible.

·         The design and construction of the pivoted joint between these couplers and coach permits vertical deflection of ±75mm and horizontal deflection of 284 mm or 13º on either side and as a consequence enables the coaches to couple up at all track curves and also on points of change of gradient even at maximum height difference between the two coaches.