4. Description

Background:

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 with a set preload. The magnitude of the During the Train movement there will be variation in relative movement between a coach and another coach or Locomotive, which causes 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 Cpl., Type BC 110/70'. This product is designed to be used in Broad Gauge Locomotives. 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 loco interface of the Train and produce a smoother ride and great comfort experience and safety for rail vehicle passengers.

Refer Sketch no-1 for the draft Gear mounted in Locomotive Draft Gear pocket.

Description of Invention:

• This invented new Draft Gear is designed for Broad gauge passenger Locomotives which absorbs the dynamic energy in both draw and buff modes. This Draft Gear mechanism is to avoid the jerks generating in existing Railway vehicle.

• 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 between two Draft Gear, End plate and Buff plate to avoid noise.

• Modularised design, where in energy absorbing device along with Buff plate and End plate of this Draft Gear assembly, can be assembled separately without handling the main heavy part called Housing. Hence productivity and safety is more here. Hence assembling and handling is very easy for the operator.

• The main part 'Housing' is made of High strength cast steel to withstand compressive ultimate load of 300 tons (minimum) in the assembled condition. The optimised design provides for ease of assembly, reduced weight to strength ratio, high productivity and interchange ability. Integrity of assembly is retained through ingenious methods while minimizing machining.

• The Buff plate and End plates are also made of High strength steel cast to with stand the tension and compressive load.

• This invented new Draft Gear does not contain any welded parts and hence will increase the quality, safety and eliminates the environmental pollution associated with totally welded structure.

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

• Draft Gear provides interface with the 'F' type shank of the coupler head. The existing fleet of 'E' type couplers with 'F' type shank can also be fitted.

• If the Draft Gear pocket length is more than the 625.5mm, preload will be increased, resulting to the increase in jerks. To avoid that, Spacers will be provided to compensate the difference in length and to retain the original preload set in the Draft Gear.

• In addition, Nitrile Rubber buttons are fitted in End plate and Buff plate parts of the Draft Gear 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 locomotive.

• These newly designed Draft Gears were fitted in Indian Railway Broad gauge Locomotives and conducted the field trails and successfully achieved the less longitudinal jerks than the existing different Draft Gears used in the Locomotives.

Technical Features of the Invented Product:

i. Compression stroke -110mm,
ii. Tension stroke - 70mm.
Hi. Dynamic Energy absorption capacity is 70 kJ (minimum) and
iv. This Draft Gear has passed the Capacity, Endurance, Sturdiness test and static test successfully and fulfilled the requirements as per the agreed test specification with the customer.

v. Electrometric pads has a travel of 110 mm in compression with maximum end load of 200 tons.

vi. Damping factor - 70 %

Draft Gear main parts:

Draft Gear consists of the following main parts. (Refer sketch no -2). For three dimensional pictorial view, refer sketch no-4.

• Housing - 2 no
• Buff plate - I no
• End plate - 1 no
• Electrometric pads (11 no)
• Intermediate discs - (12 no)
• Guiding pin - I no
• Ring - 1 no
• Bushing - 1 no
• Locating Bush - 2nos
• Mounting fixture - 1 no
• Nitrile rubber button - 8 no
• Threaded button - 8 no
• Spacer - 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 01 no of Intermediate disc in Guiding pin. Then insert one of Elastomeric pad on it. Repeat the same process until completion of the specified quantity.

d. Put the End plate with Bushing sub assembly in the above assembly from topside of the Guiding pin.

e. Take the complete sub assembly and put it in assembly fixture. End plate should come rear side of fixture and but to the assembly fixture rear end face. Buff plate should face towards Hydraulic cylinder piston side. Assembly fixture will be having a load indicator.

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

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

h. Compress the sub assembly by 110mm and note down the load shown in display indicator and release the force, i. Repeat the above scragging process for some more times until achieving the preload of 30 +5 kN at 625.5mm length between Buff plate and end plate faces.

(refer sketch no-1 ) j. Insert the Mounting fixture in Guiding pin from the rear end side of the End plate.

Insert M20 Hex. Head screw in Mounting fixture and tighten it with Guiding pin and confirm the length of 625.5mm.

Since the Locomotives car body pocket length is 625.5mm as a standard. We should not maintain the Draft Gear length 625.5mm because, if the Draft length is same as mounting pocket length, it is difficult to put the Draft Gear into the car body pocket. Hence for easy mounting it should be compress to 615 - 620 mm and tightened the M20 Bolt from the rear side of End plate and to be dispatched.

Pre load can be changed if required in future.

Now the complete sub assembly is ready for mounting it in Housing.

• There are two numbers of Housing in each Draft Gear.

• Take one no of Housing and put it on wooden plate on the ground put 2 nos of Locating bush on it. Insert the one more no of Housing on top of it (Refer sketch no-3) and fix them with M20 Hex Head screws and washers and tighten them with specified Torque.

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 625.5mm as required.

• Lift the Draft Gear in to the car body pocket and mount the Support plate and Base plate at the bottom side of draft Gear and fasten them with the car body.

• Mount the supporting device at the front end side of the car body in the specified location.

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 Draft gear Hole dia92 mm.

• 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 used for uncoupling the coupler head.

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

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

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 cpl., Type BC 110/70:

• This Draft Gear will be mounted in the Locomotive along with Coupler head and couplers.

• During the running condition, Tension and compressive load will be will be absorb by this Draft Gear.

• Energy absorbed by the Locomotive Draft Gear should be minimum 80% of the 70 kJ in compression (push) mode.

• This Draft Gear can be compressed up to 110mm in push mode and 70mm and pull (Drag) mode.

• Until reaching the extreme movement limit in Draw and push mode. Load will be will be taken by Elastomeric pads of the Draft Gear.

• Once the Draft Gear Housing is moved and butt to the End plate, the load will start acting on the Housing and not on the Elastomeric pads. Only until the completion of the compressive stroke limit, load will be taken by the Elastomeric pads. This mechanism prevents the elastomeric pads from failure.

• In Buff plate and End plate of the Draft Gears parts, rubber buttons are fitted (4 each) to avoid the noise when both are but with stoppers.

• Because of this special design of Draft Gear, jerk is formal very less and which creates in turn great comfort to the passengers.

• This type of Draft Gears with Elastomeric pads is novel and non-obvious

• Our product is already fitted in locomotive and found satisfactory results.

• Technical comparison of Our Draft Gear and the existing Draft Gear is as follows.

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

CLAIMS

5.1 We claim patent for the Draft Gear cpl. Type BC 110/70 which is having the following design features.

• Have a Capacity to withstand 300 tons of ultimate compressive and Tensile load.

• Have a capacity to absorb minimum dynamic energy of 70 kJ.

5.2 We claim patent for the method of design adopted in Housing, which is having capacity to take the compressive load of 200 tons. Easy for assembly and there is no welding in that part.

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

• Front profile design to match the Coupler head with 'F' type shank profile.

• Withstand the Tension load comes on it during operation.

• Mounted with Rubber buttons and Threaded buttons ( 4+4 no) to reduce noise in running condition of the vehicle.

• No welding in the part.

5.4 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 avoid noise in running condition of the vehicle.

• Provision made for fitting spacer when, car body length is more and to retain the required length of 625.5mm.

5.5 We claim patent for the Elastomeric pads 11 no quantity per assembly with respective quantity of Intermediate discs. The elastomeric pads are having the capacity to absorb dynamic energy of 70kJ (minimum).

5.6 We claim patent for the Ring, which is designed to hold the Guiding pin and elastomeric pads which facilitates the movement of Buff plate during operation.

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

5.8 We claim patent for the spacers, which are designed to fix into the End plate whenever required, to retain the fixed mounting length of 625.5mm in car body pocket.