Deutsche Bahn

Welding of Lower Shelf Bracket

ESG Rail was commissioned to investigate an issue with the lower shelf bracket assembly on Drophead and Alliance couplers


DB ESG was commissioned to investigate an issue with the lower shelf bracket assembly on Drophead and Alliance couplers fitted to Mark 3 HST trailer and loco-hauled coaching stock, which were becoming loose occasionally.

A Finite Element Analysis (FEA) study was undertaken to establish the stresses experienced by the current connections. The feasibility of removing the fasteners and welding the bracket directly to the coupler was investigated. The FEA study gave positive results for the option of welding the bracket. DB ESG produced a modification procedure CR/MP2217 to facilitate a trial of this proposed welding solution.



  • Problem investigation and solutions feasibility study conducted.
  • Drawings and model created to reflect the changes required to the arrangement of lower shelf bracket.
  • FEA was performed on the proposed modifications to prove that the welding would not affect the integrity of the parent material, demonstrating the proposed weld procedure would provide sufficient strength for in service use.
  • Modification procedure created.

Trial and testing

  • DB ESG developed a modification procedure (CR/MP2217) detailing the method of welding the lower shelf bracket for the purposes of the trial.
  • DB ESG supported an initial 6 month trial of the modified couplers  (4 x Drophead and 4 x Alliance couple types).To minimise the risks involved with the trial, non-destructive testing (NDT) and inspection criteria were developed and detailed within the modification procedure for the trial period, with a reporting mechanism to highlight any issues arising.
  • DB ESG contracted Railway Approvals Limited to provide Vehicle Acceptance Body (VAB) approval of the modified couplers and to confirm that the measures put in place within the modification procedure minimised any potential risk.
  • Due to the complexity of the welding procedure and the standard of welding required, DB ESG supported Porterbrook and their supplier to verify the weld quality and success of the modification procedure.

Full fleet Rollout

  • The trial was successful and Porterbrook are now looking to roll this modification out across the fleet.