Rail Grinding Machine Overview

Rail Grinding Machine (RGM)

• Rail grinding re-profiles the railhead to optimize wheel-rail contact and improve their interaction.
• Increased rail and wheel life are expected benefits, alongside reduced defect generation.
• Indian Railways utilizes 72 stone grinders of the RGI Series, manufactured by Loram (USA).

Purposes of Rail Grinding

• Reduces contact stress and maintains proper wheel steering, minimizing wear and tear on rail and wheel surfaces.
• Shifts wheel contact away from areas with surface defects, preventing further defect growth.
• Avoids wheel contact with misaligned welds, reducing hunting on straight tracks and subsequent damage.
• Controls damage from rolling contact fatigue by removing cracks in their early stages, hindering their development and reducing rail/weld failures.
• Removes corrugations and other irregularities from the rail top, leading to improved riding quality.
• Restores the rail crown radius, reducing hunting and damage caused by the flattening of the rail radius over time.
• Removes the white martensitic layer on the rail top, which is brittle and contributes to crack formation.
• Addresses dip formation near welds arising from the difference in hardness between the rail and the heat affected zone (HAZ).

Process for Assessing Contact Band

• Paint or chalk is applied to the rail surface and a freight train is allowed to pass over it.
• The erased area creates a "band" where the wheels made contact.
• This information, along with details of location, date, width of the contact band, and distance from the gauge face, are recorded both in writing and with a photograph.

Dye Penetration Test

• Conducted at the second portion of the test site to highlight damage, including cracks, on the rail surface.
• Performed both before and after grinding.
• Reduction in both number and length of cracks after grinding indicates the effectiveness of the grinding process.

Monitoring Rail Surface Finish

• The quality of the grinding is assessed by examining the rail surface finish after the process.
• A good finish exhibits regular grind marks from the grinding stones (facets) with a silver finish.
• Faulty finishes display irregular marks, skipping grinding at regular intervals, blue coloring on rails (blueing defect), or irregular facet widths.
• Ideal facet width is approximately 10 mm in the center of the rail and 4 mm at the corners.

Surface Roughness After Grinding

• The rail surface should not be excessively rough after grinding.
• Surface roughness levels should remain below 12 microns.

Grind Quality Index (GQI)

• Measures the effectiveness of grinding in achieving the target rail profile.
• GQI 100 represents full achievement of the target profile.
• Lower values indicate greater deviation from the target profile.
• During operation, GDMS screen displays GQI for both rails before and after grinding.
• Acceptable GQI is 80 and above.

Crown Radius Measurement

• Crown radius of the railhead is measured before and after grinding using a star gauge.

Safety Precautions for Crane Operation

• Ensure crane stabilization and engaged parking brakes before operation.
• Avoid operating the crane in strong winds exceeding 50 km/h.
• Maintain a clear view of the work area and confirm the absence of personnel within the crane's operating radius.
• Continuously monitor the crane's stability during maneuvers.
• Review the load to be lifted and the operating radius according to the Load Distance Diagram.
• Exercise caution when working near electric power cables.
• Never leave the machine unattended with the boom extended and load lifted from the ground. If unavoidable, lower the load to the ground and switch off the vehicle.
• Preferably load/unload and handle materials from the cess side of the track. When handling materials between tracks, ensure proper track protection on the adjacent running track side.
• Lock the crane movement to the infringing side during operation.
• Avoid using single-point slinging to prevent bending and damage of the rail surface. Keep the overhang to a maximum of half the distance between lifting points.
• Limit loading of rails and sleepers on Bulk Freight Railcars (BFR) in Utility Track Vehicles (UTVs) and Rail Borne Maintenance Vehicles (RBMVs) to 4 and 3 layers, respectively.
• Maintain horizontal and straight orientation for rails during lifting and moving.
• Secure rails by lifting support posts/foldable sidewalls or by chaining them after loading for safety before movement.
• Distribute the load evenly to prevent eccentric loading.
• Handle the crane with caution in electrified territories and station yards.
• Prohibit staff from standing beneath suspended loads for safety.
• Require staff to wear protective gloves and industrial shoes to minimize injury risk.

Safety Precautions Specific to UTVs

• A SSE/JE (P.Way) will act as a guard on the machine.
• The guard and machine staff should be assigned to the BRN for safety when the machine moves towards the crane side with an attached BRN.
• Ensure the flat wagon has a valid BPC for movement.

GDMS Data Format

• Column 1: Id - Text - Recommended: Row number in the file, aiding editing.
• Column 2: LineSeg - Text - Required: User-provided name of the track line segment. Names consisting of letters, numbers, underscore, or dash.
• Column 3: Region - Text - Required: Railroad Region.
• Column 4: Division - Text - Required: Railroad Division.
• Column 5: Sub Division - Text - Required: Railroad Subdivision.
• Column 6: Track - Text - Required: Track Name (e.g., UP, DN, SL, 1, 2, 3, etc.)
• Column 7: Start - Float - Not Used: Start Sta+Off of track segment.
• Column 8: End - Float - Not Used: End Sta+Off of track segment.
• Column 9: Km - Int - Required: Integer value specifying the kilometer location.
• Column 10: StartM - Int - Not Used: Start Meter.
• Column 11: Length - Float - Required: Length in meters of the specified kilometer.
• Column 12: CurveNum - Text - Not Used: Curve names assigned by the program based on curve start point.
• Column 13: ST - Sta+Off- Required: The first point of the curve.

Utility Track Vehicle (UTV) and Rail Borne Maintenance Vehicle (RBMV) Dimensions

• UTV (PHOOLTAS):
  • With mobile crane:
    • Length: 13170 mm
    • Width: 3950 mm
    • Wheel Axle DIA: 915 mm
    • Wheel Axle Load: 20.0 t
  • Without mobile crane:
    • Length: 13170 mm
    • Width: 3550 mm
    • Wheel Axle DIA: 915 mm
    • Wheel Axle Load: 20.0 mm
• UTV (OEPL):
  • Length: 10270 mm
  • Width: 3830 mm
  • Wheel Axle DIA: 915 mm
  • Wheel Axle Load: 13.5 t
• UTV (BEML):
  • Length: 12120 mm
  • Width: 3550 mm
  • Wheel Axle DIA: 915 mm
  • Wheel Axle Load: 15.0 t
• UTV (BHEL):
  • Length: 9770 mm
  • Width: 4115 mm
  • Wheel Axle DIA: 1092 mm
  • Wheel Axle Load: 20.0 t
• ** All dimensions are in mm.**

Rail Grinding Machine (RGM)

• Rail grinding re-profiles the railhead to optimize wheel-rail contact and improve interaction.
• This increases rail and wheel life, while reducing defect generation.
• Indian Railways uses 72 stone grinders from Loram, USA.

Purposes of Rail Grinding

• Reduces contact stresses and maintains favorable wheel steering.
• Shifts wheel contact away from rail surface defects, preventing further growth.
• Prevents wheel tread contact with misaligned welds, reducing hunting and damage.
• Controls rolling contact fatigue damage and removes cracks in early stages, preventing further growth and failure.
• Removes corrugations and irregularities, improving riding quality.
• Restores rail crown radius, reducing damage caused by wheel flattening.
• Removes the white martensitic layer on the rail top, which is brittle and prone to cracking.
• Addresses dip formation near welds due to differential wear, which occurs because of the difference in hardness between the rail and the heat affected zone (HAZ).

Grinding Strategy

• Metal removal and grinding frequency are determined to control rolling contact fatigue.
• Corrective grinding removes all corrugations and defects in a single cycle, achieving the target rail profile.
• Preventive grinding is done early in defect generation, more frequently, with less metal removed per cycle.
• Preventive-Gradual Grinding is the adopted strategy on Indian Railways, removing more metal than preventive grinding, but less than corrective grinding.
• Aim is to achieve preventive grinding after 3-4 cycles.
• Target rail profiles are designed to minimize contact stress during wheel-rail interaction.
• Profiles vary for straight tracks, curved tracks, mild curves, sharp curves, high rails, and low rails.

Rail Borne Maintenance Vehicle (RBMV)

• Features include two driving cabins, cabins for men and material, a hydraulic crane, diesel engines, and hydrodynamic power transmission systems.
• The crane is used for loading and unloading materials.
• The vehicle has two diesel engines (Cummins NTA855R), each driving one bogie.
• Two hydrodynamic power transmission systems are used for driving and grinding.
• The vehicle is 22,270 mm long, 21,000 mm wide, and 14,783 mm high.
• The maximum load capacity is 18.25 tonnes, with a width of 3,245 mm.

Post Grinding Operations

• Rail profile is measured within 15 days after grinding at test sites.
• Dye Penetrant Test (DPT) is conducted within 10-15 days for defect detection, and a photograph is taken.
• Surface photos are also taken within 10-15 days.
• MINIPROF measurements and photographs are archived.

Operating Procedures

• Regularly check the motor performance through the HMI panel.
• Prepare a chart in advance outlining the grinding patterns for the first pass.
• Synchronize the chainage of the track and the machine before and during operation.
• Ensure the SSE/JE/TM selects the correct grinding patterns.
• Verify the grinding speed is accurate.
• Monitor the SSE/JE/TM's motor sequencing during obstructions.
• Verify the direction of the curve in the GDMS software matches field observations.
• When the curve direction is incorrect, avoid using GDMS suggested patterns for the second and third passes and choose them manually.
• Correct the GDMS data to prevent future issues.
• Ensure prompt pattern changes by the SSE/JE/TM when entering or exiting curves.
• Measure the GQI before and after grinding to assess improvements.
• Learn how to use the GDMS software, including pattern and speed recommendations for curves.
• Monitor the patterns in use in real-time.
• Respond promptly to any alarms on the HMI.
• Ensure that the buggies are lowered and raised on straight track only.