Brake Binding in coaching stock:

Whenever brake block grips the wheel with excessive braking force, it is termed as brake binding. It is the burning problem of the day in all types of rolling stock.

Repercussions of brake binding in operation are as under:
  • Detention to trains causing loss of punctuality of trains.
  • Flat places on the tyre of wheel leading to bearing failure, weld failure& rail fracture etc.
  • As a preventive measure, the detachment of coach/ wagon en-route causing inconvenience to the passengers during their journey.
  • Ineffective percentage of coaching stock increases and thus, maintenance cost is also increasing.
  • More Tractive force needed by locomotive to haul even light load train.
Brake Binding:

The brake binding occurs in all types of rolling stocks irrespective of air brake or disc brake. During release even after restoration of brake pipe pressure to 5.0 Kg/Cm2, the brakes do not release due to various reasons and thus wheels not move freely on the track. This phenomenon is called brake binding.

What are the effects of brake binding?

  • It damages the wheels
  • Draft of Trouble shooting Guide on Brake-Binding in Coaching Stock
  • It damages the bearings
  • It gives discomfort to the passengers
  • It leads to detention to the trains
  • It leads to detachment of rolling stock enroute
  • It leads to train parting
  • It leads to High power/fuel consumption
  • It also damages the track.
Causes of brake binding:

The main causes of brake binding due to failure :

  • Brake power creations system (Pneumatic system)
  • Brake power transmission system (Brake rigging)
  • Human Failure/Negligence
  • Miscellaneous Factors
Causes of Brake binding in the power creation system:

All the components which are available for the passage of compressed air between loco and the brake cylinder come under the power creation system.

  • Any failure in these parts between loco and the brake cylinders results in brake binding.
  • The main parts come under power creation system are:
  • MU washer
  • Palm ends
Draft of Troubleshooting Guide on Brake-Binding in Coaching Stock:
  • Air Hoses
  • Cut-off angle cock
  • Brake pipe,
  • PEAS,
  • Guard Emergency brake Van valve
  • Dirt collector
  • Auxiliary reservoir
  • Control reservoir
  • Distributor valve
  • Brake cylinder
  • Feed pipe
Brake binding due to air pressure leakages:
  • Defects in MU Washer
  • Defective Palm Ends
  • Defective Air Hoses
  • Leakage through Cut- off Angle Cock
  • Leakage through Brake pipe
  • Leakage through Dirt Collector
  • Leakage through DV joints
  • Leakage through AR
  • Leakage through Brake cylinders
  • Leakage through PEAS
Draft of Troubleshooting Guide on Brake-Binding in Coaching Stock:
  • Leakage through GEV
  • Defects related to DV:
  • Mounting of DV on common pipe bracket.
  • Assembly of DV with the Intermediate flange.
  • Malfunctioning of DV.
Brake binding due to overcharging of CR:

Due to the difference in calibration of brake pipe pressure gauges in the locomotives, there is a chance of overcharging/undercharging of BP pressure during loco changing, even though pressure gauge indicates 5.0 Kg/Cm2 Pressure which results in brake binding throughout the formation due to differential pressures in the incoming/ outgoing locos.

Whenever the locos are reversed at the junction stations. Sometimes it becomes difficult to charge 5.0 Kg/Cm2 pressure in the rearmost vehicle, whereas, CR already remains charged with 5.0 Kg/Cm2 before the reversal of locomotives. This difference of the pressures causes brake binding in the rear portion of the train.

Brake power transmission system: (Brake rigging):
  • Brake cylinder defective.
  • Improper alignment of Brake Cylinder
  • Draft of Troubleshooting Guide on Brake-Binding in Coaching Stock
  • Uneven thickness of brake block on the same truss beam.
  • Handbrake fully or partially on.
  • Brake block mounting over the wheel.
  • Brake shoe jamming.
  • Brake beam rigid.
  • Improper manual adjustment of brake gear.
  • Fitment of the wrong type of brake block (L-type instead of K-type and vice versa)
  • The system through which the brake forces that available on the piston is transmitted to the wheel is called power transmission system.
Human Failure/Negligence:
  • Non releasing of the DV manually during engine changing/reversal.
  • Mis-understanding of Brake block release as CR charged during
  • Engine change/reversal.
  • Miscellaneous Factors:
  • Dust/Dirt & Moisture in the Air supplied.
  • Mixing of different Stocks:
  • Under Frame Mounted with BMBC Stock.
  • BMBC stock with and without relay
Pressure Gauges:
  • Non-usage of the standard Pressure gauge.
  • Draft of Troubleshooting Guide on Brake-Binding in Coaching Stock
  • Non-calibration of Pressure gauges at regular interval.
  • Breakages in the pipe connection between DV and the Brake cylinder

causes brake binding. How?

Breakage in the pipe connection between DV and the brake cylinder leads to excessive leakages of air from AR after the brake application. This excessive leakage drops the MR pressure abruptly. Once MR Pressure drops, it is not possible to restore the BP pressure to 5.0 Kg/Cm2 during release, results in brake binding in the entire formation.

Remedial measures: – Detect and Isolate the DV:

How the leakage in the Auxiliary reservoir causes brake binding?

In case of single pipe, the auxiliary reservoir is charged through the brake pipe. Excessive leakage in the A.R due to working out of drain plug or corrosion and the foreign body hitting on the AR prevents recharging of BP to 5.0 Kg/Cm2 results in brake binding on the entire formations.

Remedial measures: -Detect and Isolate the D.V.

What are the common defects in the brake cylinder that cause brake binding?
  • The brake binding can happen due to the defects developed within the brake cylinder due to the,
  • Bent piston rod Draft of Troubleshooting Guide on Brake-Binding in Coaching Stock
  • Weak/ broken return spring
  • Jammed piston
What are the defects in the SAB causes brake binding?

The defects in the automatic slack adjuster cause malfunctioning of the same on enroute. This sometimes results in the brake regulator not paying out slack after brake application and subsequent release. This results in brake binding.