PSM Sorter Under Guard (Safety & Ergonomic Improvements) Re-Design & PSM Engineering Safety Modifications Update

PSM Sorter Under Guard (Safety & Ergonomic Improvements) Re-Design & PSM Engineering Safety Modifications Update:


Following the introduction of the new generation(1A/1B) Parcel Sorting Machines (PSMs) an issue was identified and discussed in detail at the RM/CWU National Joint PSM Safety Sub-Committee in relation to an unfortunate consequence of the ‘Equinox sorter design’ that parcels can fall from the trays at the sorter corners onto the under guarding. As the standard guarding design is fixed with no under guard access, it is a difficult, awkward task to recover fallen parcels that can build up in numbers and the only practical method is to reach for them from above by accessing them from within Mobile Elevating Work Platforms (MEWP). Recovery of the fallen parcels is difficult as they need to be pulled up through the sorter tray carriers using a grabber tool and this action can lead to engineers over-reaching, stretching etc., with the potential of back and arm strains.

The machine manufacturers and suppliers were approached but were not prepared to change the under guarding design as they believed the contractual obligation regarding through-put, rejects, mis-sorts and flyout items had been achieved and the contract terms satisfied.

Consequently, with the safety and ergonomic problem identified, Royal Mail decided to undertake an in-house re-design of the under guarding to significantly improve the search and recovery of fallen parcels in a safe and ergonomically sound way.

Concept Design 

Under the leadership of Les Curtis, Royal Mail Engineering PSM Asset Manager, the PSM project team conceived various ideas of under guard designs with the Swindon based on-site technicians. This resulted in cardboard mock-ups being stuck onto the sorter to assess the feasibility.

Following on from this, an external ergonomist designer was engaged to develop 3D visualisations of various potential designs along with scale models to show how they could look at how the fallen parcels could be safely and ergonomically recovered efficiently and comfortably in the PSM working environment.

The design had to take account of many different and often conflicting requirements, such as: head room, walkway clearance, overall safety, parcel recovery access, appearance, materials, viewing panels, robustness and maintenance.

Meetings of the RM/CWU National Joint PSM Safety Sub-Committee took place at PSM offices and workshops with the on-site engineering technicians in both Swindon MC and Warrington MC to agree the best design approaches to take forward. At this stage, it was decided a chute at corner 1 was a key design requirement, but corners 2 and 3 would not have a chute due to operational work area constraints.

The chosen design was developed and a full-size modelling board version was constructed and attached to the Swindon PSM to initially verify its form, fit and function.

The 3D design was converted into sketches so that Royal Mail Engineering’s PETRA group could manufacture the panels in sheet aluminium in their Swindon workshop.

The prototype panels were then assembled onto a full-size wooden test rig built in the PETRA Swindon workshop which simulated a PSM sorter corner of the live machines. This enabled the design to be verified and tested before being fitted to a live operational machine. The testing included ensuring parcels did not get trapped, that the guarding was strong enough to retain the full weight of a York full of fallen parcels and that the parcels could be safely and easily removed through the access hatches or drop safely down the chute.

Once testing was successfully completed, the PETRA team dismantled the guarding from the test rig and fitted it onto the operational PSM in Swindon Mail Centre for live trials. The trials were run during the Christmas peak and proved successful.

Feedback from the on-site technicians at Swindon MC after the live trial led to further improvements to the prototype production design.

The main trial points were:

  • The hatch key lock was awkward to use.
  • The hatches need to be slightly taller to improve parcel removal.
  • The hatches need to be held in the open position to free both arms for parcel removal.

The production version addresses these by:

  • Changing the hatch lock to an easy to use square security key.
  • Increasing the hatch openings to the maximum possible height.
  • Installation of gas springs on each hatch to hold them in the open position.

KPK Sheet Metal Fabricators were commissioned to convert the prototype design into a production design. KPK have state-of-the-art sheet metal laser cutters and larger capacity power bending equipment and machinery, so, the production version design is simplified and manufactured to closer tolerances. KPK subsequently manufactured the corner 1 production version and this was installed by the PETRA team to replace the prototype on the Swindon MC PSM. The design fitted perfectly, confirming this corner design is now ready for fleet wide national roll-out.

The production designs for corners 2 and 3 are slightly different as neither can have a chute. The designs are nearly finalised and production versions will be manufactured and planned to be fitted on the Swindon MC PSM machine during April 2021. There is no change to the corner 4 under guard as parcels seldom drop from the trays at this corner, so it will remain as provided by the machine supplier.

National PSM Fleet Wide Roll-Out and Deployment 

The deployment of the new Sorter Under Guards across the Royal Mail PSM fleet is now being planned. The intention is to deploy the guarding on the three corners to all 20 operational PSMs during the Summer and Autumn of 2021, prior to Christmas peak.

See attached photographs/images of the re-designed, modified PSM Under-Guard.

RM Driven Safety Modifications

Additionally, Royal Mail has developed 25 safety related modifications for the PSM machines. 19 modifications have already been deployed. 2 modifications are in development. 4 RM modifications are ready to deploy. See below list of all 25 modifications.29014Sorter Under-Guard Fixings ReplacementMod Deployed29015C4 Anti Tip Brackets ReplacementMod Deployed29016AC Torque Arm Safety Brackets InstallationMod Deployed29017Installation of Davit Arm Lower MastMod Deployed29018C3 Conveyor Bump Stop InstallationMod Deployed29019Improved Operator Workstation FansMod ready to deploy29022Unused Chute Vinyl StripsMod Deployed29023Sorter Corner Infill PanelsMod ready to deploy29026Fit padding to vertical beam at base of stairs to DWS 2Mod Deployed290292 Hand Controller Cable Parking SocketMod Deployed29030Induct Operator Table Edging StripMod Deployed29033Fitting of modesty panelsMod Deployed29037Tipper Release ButtonMod Deployed29038Installation of Operator Chair Rubberized Wheel CastorsMod Deployed29039Conveyor C15 Safety Signage InstallationMod Deployed29040Raise DWS Cross BarMod Deployed29043C4 Gate Infill PanelMod Deployed29046Issue of Special Tool J194Mod Deployed29053Tipper Door Mesh BracketsMod Deployed29057Additional Earth BondingMod Being Prepared29058Eject Chute NettingMod Being Prepared29059Over Sized Parcel Recovery PullerMod Being Prepared29062Suction Cup SWL LabelsMod Deployed29065Reject Chute Edge ProtectionMod Deployed290??AC Outside Spill NettingMod In Design


  • Photographs/images of the re-designed, modified PSM Under-Guard.
  • Photographs/images of the safety modifications.

Yours sincerely

Dave Joyce
National Health, Safety & Environment Officer

LTB 134/21 – PSM Sorter Under Guard (Safety & Ergonomic Improvements) Re-Design & PSM Engineering Safety Modifications Update

PSM Sorter Under Guard Safety Ergonomic Improvements Images

Safety Modifications

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