Lee Enfield 2-stage trigger

Fig.1 The action is cocked, trigger pressure is taken up, the bottom trigger nib is on the sear and as it is pulled, the sear comes lower down the face of the bent.
Fig. 2 The sear is on the bent at the point where the first stage is completed.
Fig.3 The upper nib on the trigger takes over contact of the sear. Being further away from the pivot, this takes increased pressure to continue movement.
Fig.4 The sear is now moving down the face of the bent toward the bottom or “break” point.
Fig.5 The trigger has pulled the sear down off the bent and allowed the mainspring to re assert and fire the action