VDHI RAILWAYS

SSE-Van Der Horst Indonesia is a pioneer in the reconditioning of liners, crankshaft and con rods for the locomotive diesel powered engines.

In recent times it's expertise had been extended to repair, resizing and life extenson of the wheel-sets using the DALIC technology

 


The wheel-sets

The wheel-set of a railway carriage consists of:

The axle: it is the steel cylindrical part which transfers to the rail the weight of the rolling stock and includes:

  • The axle beam
  • 2 wheel bearing journals
    2 roller bearing journals
    Engine or gears bearing journals (if loco axle)


The wheels : the wheel body and wheel bandage

The bearings : single or mounted in cartridge


What are effecting the axle during the run on rails ?

Wear factors :load on the axle vibrations, interference between bearing and journal, sand, dust temperature, climate, design of track and of rolling stock boogie.
Fatigue : Alternate flexion-rotation

  • 8 cycles per sec, with up to 30 MT load for heavy trains
  • 30 cycles per sec, with 17 MT load for high speed trains

Critical areas : journals and bearing cone bores

 


An Example of the Investigation & Rectification of Damage on Axles : 

CAUSE : fretting-corrosion

It results from vibrations, abrasion,
and appears as oxides particules, corrosion,

=> Loss of dimensions up to 120 microns
on the 4 bearings and wheel journals

=> DALIC technical proposition :
An alloy Nickel : 85%   Cobalt :15%


PURPOSE:  An under layer of nickel improves adhesion and compensate the loss of dimension due to etching

The final coating of Nickel Cobalt alloy:

final-4-year

The metallurgical evaluation :

  • Ultrasound examination : no internal damages
  • Visual examination : no visible defects
  • Coating adhesionTest : done with adhesive tape  
  • Cracks détection : 10’ in HCL 50%at 100°C
  • Microscope analysis : uniforme coating layer
  • Measured hardness : 60Rc
  • Bending test at 150° : no peeling of the coating
  • EBM analysis : small and regular nodules on surface

Evaluation in service

1. Mounting of bearing on the journals

  • 12 axles fitted with bearing then dismounting and mounting of bearings is done 10 times
  • Final dimension loss on the journal : 4 to 5 microns

2. Conditions and results of evaluation

  • 50 wagons, 200 axles , 400 bearings
  • 4 years, 26 MT workload,  from 20 to 85 °C
  • Coating is safe and adhesive
  • Dimension loss in bearing cone bore : 5 microns