Specialist Norbar torque tool ‘made-to-order’ for London Underground

Norbar Torque Tools’ specialist engineering department has developed a unique torque tool for London Underground.

The new tool has been developed to solve a specific engineering challenge, namely the removal and refit of the inter-car coupler mounting bolts on the fleet of 47 Bombardier 09 Stock trains used on the Victoria Line in London and maintained at the Northumberland Park depot.

The inter-car coupler mounting bolts are accessed from the underside of the train, either from the pit road or with the train jacked up. The coupler mounting has four bolts with a significant boss in the middle that houses the Absolute Position Reader (APR).

Difficult to access

Of the four bolts, the upper two were particularly difficult to access, due to them being deeper up into the train and surrounded by other hardware. The bolts are required to be tightened to a torque of 1,050 N.m.

London Underground’s tool supplier, Hayley Group, contacted Norbar with the remit of providing one tool to reach all of the bolts on the coupler.

The Norbar solution was to use a Pneutorque PTS tool with a specially developed drive that is slim, long and offset from the PTS square drive, with a series of gears arranged in line and driving each other. This enables all of the bolts on the Bombardier 09 Stock trains to be reached during maintenance.

In addition, the gearbox of the tool is supplied with quick-change reaction arms in order to reach all of the bolts and safely take torque reaction from the tool.  The aluminium-bodied gearbox can also be positioned on the bolt before the driving tool is coupled. This significantly reduces the total weight that has to be lifted and makes the location of the offset gearbox and its reaction plate much easier.

Solving complex bolting challenges

Philip Brodey, head of new product development at Norbar Torque, comments: “Our Specialist Engineering Department is dedicated to solving complex bolting challenges that require bespoke solutions. When Hayley Group and London Underground approached us about their bolting challenges at the Northumberland Park depot, it was clear that the Bombardier 09 Stock trains would require a specialist solution.

“We chose the pneumatic ‘Pneutorque’ PTS tool as the basis for the specialist torque wrench, due to its quiet and smooth power source, allied to its accurate torque delivery. The development was a complex process that involved the use of a 3D printed model to ensure that the tool could reach all of the bolts required.

“We are very pleased with the final result, as there is no off-the-shelf solution to an application such as this. We have developed one tool that reaches all of the bolts, whilst retaining power, accuracy and safety for the operator.”