4. Description Background:

During the Train movement there will be variation in relative distance between a coach and another coach or Locomotive, which causes for them to move close(buff mode) / move apart (draw mode). This relative motion during Draw mode and Buff mode exerts forces on rail vehicle structure which ultimately felt as jerks by Passengers.

Draft Gears for Railway application are used to absorb the Energy, to reduce the jerks and for smoother ride of the vehicle. At present most of the draft gears offered are of unidirectional type and shows very stiff spring characteristic at high preload as well as system allows a great amount of free slack in the pocket. This generates or initiates high forces especially during load reversals for the locomotives and induces propagation of jerk in the train. The magnitude of the preload determines jerks experienced by passengers. During the reversal of motion, this set preload appear as additional load on the rail vehicle structure, causing a feel of jerk by the passengers. Higher the preload lower is the comfort level experienced by the passengers.

Product which is subject matter of the Invention:

An invention of a product is by name 'Draft Gear with Floating plate CPL Type BC 80/45F’ This product is designed for Broad Gauge (BG) Passenger coaches. This Draft Gear with low preload and low stiffness will be able to absorb the shock / Energy in both Buff and Draw modes and minimise the jerk excitation to a great extent at the coach interface of the Train and produce a smoother ride and great comfort experience and safety for rail vehicle passengers.

Description of Invention:

• This invented device 'Draft Gear with Floating Plate CPL Type BC 80/45F' (Refer sketch no- 1) is designed for use in Broad Gauge passenger coaches which absorbs the dynamic energy in both draw and buff modes. This Draft Gear mechanism's significant advantage is, after compression mode, it allows nearly a zero preload in reverse direction because of residual forces and avoid the jerks producing in the existing Railway vehicle. This mechanism of the Draft Gear makes its function novel and constitutes the inventive step.

• In this Draft Gear, during compression stroke, all Elastometric pads will be compressed. However, during tension stroke only those Elastometric pads which in between Buff plate and Intermediate will compress and Intermediate plate also move forward up to the stroke limit. The Elastometric pads which are fixed between End plate and Intermediate will expand accordingly. This is main functional advantage to get the zero preload during load reversal.

• This invention is to provide smoother ride of the railway vehicle and to increase the efficiency of the Draft Gear.
• In addition. Rubber pads are fitted in Draft Gear, End plate and Buff plate to reduce noise.

• The main part 'Housing' is made of High strength cast steel to withstand compressive ultimate load of 200 tons. The optimised design provides for ease of assembly, reduced weight to strength ratio, high productivity. Integrity of assembly is retained through ingenious methods while minimizing machining.

• On top of the Housing, Wear plate (rear end) and Slide plate (outer) are fixed to reduce the noise and to avoid damage of Housing during Train running condition.

• The Intermediate plate (Floating plate) is made of High strength steel to with stand the compressive load.

• Application of service proven high dampening Elastomeric pads will enhance a service life of 6 years for the Draft Gears.

• This Draft Gear with Floating plate is designed to suit the Car body pocket length of 510mm.

• In addition, Nitrile Rubber buttons are fitted in End plate and Buff plate parts of this Draft gear with Floating plate, to avoid noise during load reversals. The faces where the Nitrile rubber buttons are fitted will be but with the Front and Rear stoppers of the coaches.

• Various coaches used by railways like LHB coaches / conventional conversion type coaches can be fitted with this invented Draft Gear with Floating plate CPL Type BC 80/45F

5. Newly Invented Draft Gear is having the following technical features :

i. Compression stroke - 80mm,

ii. Tension stroke - 40mm.

iii. Dynamic Energy absorption capacity is 45 Kilo Joules (minimum)

iv. This Draft Gear will pass the Capacity, Endurance and Sturdiness test.

V. Electrometric pads has a travel of 80 mm in compression with maximum end load
200 Tons,

vi. Damping factor - 60 %

Draft Gear main parts:

Draft Gear consists of the following main parts. (Refer sketch no -2)

• Housing -1 no
• Buff plate - I no
• End plate - 1 no
• Intermediate plate - 1 no
• Electrometric pads (9 no)
• Intermediate discs - (7 no)
• Guiding pin - I no
• Ring - 1 no
• Locating Bush - 2 no's
• Mounting fixture - 1 no
• Nitrile rubber button - 10 no
• Threaded button - 10 no
• Slide plate outer - 1 no
• Wear plate (rear end) - 2 no
• Fasteners - as specified in drawing.

Draft Gear assembly procedure to achieve required preload: (Refer sketch no.
2&3)

a. First put the Buff plate on wooden plate, which is mounted on the ground.

b. Take the Guiding pin and insert it in Ring. Those sub parts are to be kept in Buff plate pocket and insert the M12 Hex. Head screws (3nos) and fix them with Buff plate.

c. Now insert one of Elastomeric pad on Guiding pin. Then insert 01 no of Intermediate disc.

d. Total 9 no of Elastomeric pads and 7 no of Intermediate discs will be used in this Draft Gear. 4 no of Elastomeric pads and 3 nos of Intermediate discs will be inserted between Buff plate and Intermediate plate. Remaining 5 no of Elastomeric pads and 4 no of Intermediate discs are to be inserted between Intermediate plate and End plate.

e. Now, take the Housing and keep it in wooden plate on the floor.

f. First insert Intermediate plate into the pocket made in the Housing.

g. Insert Buff plate with Guiding pin and Elastomeric pad sub assembly (as assembled in stage 'c' above) in to the Housing. Guiding pin should pass through the Intermediate plate mounted in the Housing.

h. Now insert Elastomeric pad (1 no) in the Guiding from the other side of Housing. Put Intermediate disc on it. Total 5 no of Elastomeric pads and 4 nos of Intermediate discs are to be put on Guiding pin between Intermediate plate and End plate.
i. Note: If required Elastomeric pads and intermediate plate quantity can be reduced by redesigning.

j. Put the End plate with Bushing sub into the Guiding pin.

k. Take the complete sub assembly and is to be put it on the assembly fixture. End plate should be placed towards rear side of fixture and butt it. Buff plate should face towards Hydraulic cylinder piston side. Assembly fixture will be having load indicator.

l. Now put the load cell between Buff plate face and Cylinder piston face.

m. Switch on the electric connection and operate cylinder by manually operating switch.

n. Compress the sub assembly by 80mm and note down the load shown in display
indicator and release the force.

o. Repeat the above process for some more times until achieving the preload of 30 +5 KN at 510mm length between Buff plate and End plate faces, (refer sketch no-1)

p. From rear end side of the End plate, insert the Mounting fixture in Guiding pin and tighten it with M20 Hex. Head screw and confirm the length of 510mm.

Since the Locomotives car body pocket length is 510mm as a standard. We should not maintain the Draft Gear length 510mm during dispatch because, if the Draft Gear with Floating length is same as mounting pocket length, it is difficult to put the Draft Gear with Floating into the car body pocket. Hence for easy mounting, it should be compress to 500 to 505 mm and tightened the M20 Bolt from the rear side of End plate.

Pre load can be changed if required.

Now the complete sub assembly is ready for mounting it in Draft Gear pocket.

Mounting of Draft Gear in Locomotive and its performance:

• Take the Draft Gear by a lifter and put it on the Trolley.
• . First, measure the car body pocket length of 510mm as required..
• Lift the Draft Gear in to the car pocket and mount the Support plate and Base plate at the bottom side of draft Gear and Bolt them with the car body.
• Mount the supporting device at the front end side of the car body pocket.
• Now put the Tight Lock coupler head with Transition screw in the Draft Gear front end and insert the Central pin from bottom side of the Base plate into the Draft gear Hole dia 80mm.

• After fixing the Central pin Insert the locking plate into the base and fix it with the specified Bolt. This locking plate is fixed to hold the Central pin.

• Mount the Manual Uncoupling device at the front end of car body and insert the sliding rod of uncoupling device into the Rotor assembly of Coupler head. This uncoupling device is used for uncoupling the coupler head.

• Loosen and remove the M20 Bolt and the Mounting fixture slowly from back side of End plate. Now the Buff plate and End plate will be butt with Front and Rear stoppers. Now the Draft Gear is fitted and ready for use.

When the Train starts running. Draft Gear will be start functioning. Energy will be absorbed by the Draft Gear with Floating plate in Buff mode and Draw mode to reduce the jerks and for smoother ride of the vehicle. Since the preload will be zero during load reversal, jerk will be reduced.

Since the Rubber buttons are incorporated on Buff plate and End plate, it reduces the noise during operation. Elastomeric pads are flexible not rigid. When the locomotives are running in curve, they will operate smoothly and give good results.

Description on working of Draft Gear with Floating plate CPL Type BC 80/45:

• This Draft Gear will be mounted in the Broad Gauge passenger coaches pocket along with Coupler head and other sub assemblies.
• During the running condition. Tension and compressive load will be absorbed by this Draft Gear.
• In this Draft Gear, one Intermediate plate will be there between Buff plate and End plate.
• Energy absorbed by the Draft Gear with Floating plate will be minimum 45 kJ in compression (push) mode.
• This Draft Gear can be compressed up to 80mm in compressive (push) mode and 40mm and pull (drag) mode.
• In the compressive mode. Housing will be moved along with Buff plate. Intermediate plate and all the Elastomeric pads will be compress.
• Once the Draft Gear Housing is moved and butt to the End plate, load will start acting on the Housing and not on the Elastomeric pads. Until the completion of the compressive stroke limit of Draft Gear, load will be taken by the Elastomeric pads.

This mechanism prevents the elastomeric pads from failure.

• In Draw mode, Housing will be moved along with Buff plate, Intermediate plate.
Elastomeric pads between Buff plate and End plate will compress and the Elastomeric pads between Intermediate plate and End plate will expand and gap between them will be more.If required, the gap between Intermediate plate and End plate can be retained as it is in Draw mode with slight modification in design.

• This Draft Gear could withstand the End load of 1600 KN, without any damage or cracks of parts.
• In Buff plate and End plate of the Draft Gear parts, rubber buttons are fitted (4 each) to avoid the noise, when both were butt with the stoppers.
• Because of this special design of Draft Gear, jerks will be formal very less and which creates in tern great comfort to the passengers.
• This type of Draft Gears with Elastomeric pads is novel and is not obvious
• This product is already developed and fitted in Broad Gauge passenger coaches and found satisfactory results.
• Refer to the Force diagram, it clearly shows energy absorbed during the buff mode (compression) is 45 KJ (min), which is approximately the energy required in rough shunting at 9.5 Kmph. The force diagram also shows that the force during the reversal of motion, theoretically pass through the 'zero' point.
• This product has already been tested in Broad Gauge passenger coaches and found satisfactory results.

Technical comparison of the invented Draft Gear and the existing Draft Gear is as below.
Description Draft Gear with Floating Existing Draft Gear
plate cpl. Type BC 80/45F assembly.
Have a less jerk Yes No
Noise is reduced during operating Yes No
condition
The force during the reversal motion, Yes No.
theoretically pass through "zero" preload and will get higher force less tension stroke.

6. Claims (not applicable for provisional specification. Claims should start with the preamble - "I/We claim" on separate page)

6.1 We claim patent for the Draft Gear cpl. Type BC 80/45F which is having the following design features.

6.2 We claim patent for the method of design adopted in Housing, which is having capacity to withstand the compressive load of 150 tons (min). Unique design is made to incorporate the Intermediate plate called as Floating plate.

• Have a Capacity to withstand End force of 1600 KN.

• Have a capacity to absorb the dynamic energy of 45 kJ (minimum).

• Damping factor - 60 %

6.3 We claim patent for the method of design adopted in Intermediate plate which is one of the main part acts in achieving zero preload during load reversal resulting to achieve the less jerk.

6.4 We claim patent for the method of design adopted in End plate which will be having following advantages.

• Withstand the compressive load comes on it during operation and static condition.

• Mounted with Rubber buttons and Threaded buttons (4+4 nos) to reduce noise during operation of the vehicle.

6.5 We claim patent for the Elastomeric pads, quantity 9 nos with respective quantity of Intermediate discs. The elastomeric pads are having the capacity to absorb the dynamic Energy of 45 kJ (minimum).

6.6 We claim patent for achieving the less jerk and noise for passenger comfort and smooth drive using this Draft Gear.

6.7 Pre load can be adjusted from 30KN to 50KN without changing the design.