The weighbar shaft has been placed back into position on its refurbished bearings.
This assembly is connected to the reverser in the cab and allows the valve gear to be adjusted from full forward gear through mid-gear to full reverse gear.
The weighbar shaft itself lifts the radius rod up or down to set the position of the valve gear via the forged arm that can be seen on the extreme right of the photo's.
The above view shows the right hand side of the locomotive looking towards the front. The inner bearing can be seen with its clamp in position, while the outer bearing top half can be seen on the right of the picture.