The winding pinion, shown in red, will turn when the crown is in the winding position and it needs to be connected to the ratchet wheel teeth, shown in green, to wind the mainspring.

UK watchmaker showing service of Omega Speedmaster - barrel and winding pinion

This is performed by the crown wheel which will sit on the underside of the bridge.  The teeth and bearing surfaces here are fine.

UK watchmaker showing service of Omega Speedmaster - crown wheel review

This is the underside of the barrel and train wheel bridge – it’s known as a 3/4 plate design because of its size.

UK watchmaker showing service of Omega Speedmaster - underside of bridge

The crown wheel is fitted and held in place with the crown wheel core.

UK watchmaker showing service of Omega Speedmaster - crown wheel fitted

The click is also fitted on the underside of this bridge at the upper area.  A spring is fitted later so that it is held against the ratchet wheel teeth to stop the ratchet wheel unwinding the mainspring when the turning motion of the crown is stopped.

UK watchmaker showing service of Omega Speedmaster - click fitted

The bridge is turned over, all the pivots are lined up and it’s fitted.

UK watchmaker showing service of Omega Speedmaster - barrel and wheel bridge fitted

In the lower area, the click may be seen through a cut-out in the plate.

UK watchmaker showing service of Omega Speedmaster - click spring cut-out

And the click spring and retaining screw are fitted here so that the click is pressed against the ratchet wheel.  When the ratchet wheel turns in winding mode, the click swings across this gap until the crown pressure is removed and then the spring pushes it back to this position and it locks the ratchet wheel.

UK watchmaker showing service of Omega Speedmaster - click spring fitted

The assembly continues with the escapement.