The 3D-printed components are proving invaluable in developing and refining the P2’s valve gear, allowing the engineering team to assemble the system at full scale, check how the individual components interact and identify any necessary refinements before committing to the more expensive final metal components. The latest work has seen the cam box assembled and installed in the cylinder block, providing an opportunity to examine the operation of the cams, rockers and reversing mechanism as a complete system.

This approach is giving the team a much greater understanding of how the valve gear will function on the finished locomotive and, importantly, allowing the design to be tested and refined before manufacture in metal. With the latest assembly work confirming the design in situ with the monobloc on the frames and only final refinements remaining, the team is now very close to finalising the design and moving into production of the P2’s valve gear.

We now have a 3D print of a valve, with associated parts. Above shows an inlet valve, spindle and the inner valve seat on the bench and the inlet valve installed into the cylinder block.

The images above show the cam box with the cams and rockers installed. The green worm wheel provides the drive to the camshaft, with the adjacent cam operating the inlet valves and the other two cams operating the exhaust valves.

The underside of the cam box lid can also be seen, with the reverser screw, reversing nut and fork installed. The fork operates the camshaft cut-off drive bush (the yellow component inside the cam box), which slides the camshaft to change the valve gear setting between forward and reverse.

Here, the images show the cam box assembly installed in the cylinder block. The white component is the valve inner seat, through the centre of which passes the valve spindle. The spindle is operated by the tappet, which is driven by the rocker as it follows the cam profile.

The end-on view shows the three-dimensional cam profile followed by the rocker. Because the cams are three-dimensional, moving the camshaft horizontally using the reversing screw changes the point at which the valves open and close, allowing the valve timing to be altered for forward and reverse running.

Read more about the Valve Gear design and sign up to 'The Valve Gear Club' here, alternatively you can make a donation here.