To assist with the removal and replacement of inter-car coupler mounting bolts on the Victoria Line's fleet of 47 Bombardier 09 Stock trains, Norbar created a one-of-a-kind torque tool.
The inter-car coupler mounting bolts are accessed from the underside of the train, either from the pit road or while it is elevated. The coupler's four bolts are encircled by a large boss in the middle that houses the Absolute Position Reader (APR). The upper two of the four bolts were particularly tough to reach due to their being deeper into the train and surrounded by additional hardware. The bolts, on the other hand, must be tightened to a force of 1,050Nm. The London Underground's tool vendor, Hayley Group, offered Norbar Torque Tools Ltd a contract to provide one tool that would reach all of the bolts on the coupler.
The Norbar solution was to employ a Pneutorque PTS tool with a specially designed drive that is slim, long and offset from the PTS square drive, with a chain of gears running in-line and meshing with each other. This allows you to access all of the bolts during maintenance.
The tool's gearbox is also equipped with quick-change reaction arms to reach all of the bolts and absorb torque reaction from the tool. The aluminum-bodied gearbox may be positioned on a bolt before the driving tool is connected, lowering the overall weight that must be lifted and making positioning of the offset gearbox and its reaction plate much simpler.
Philip Brodey, head of new product development at Norbar, commented: “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 the tool could reach the bolts required. We were able to develop one tool that reaches all of the bolts whilst retaining power, accuracy and safety for the operator.