This is a detail of the synchro compur 00 shutter in a late model rolleicord. Below is the escapement with the bottom cover off before ultrasonic cleaning. It’s tedious work putting one back together, and I have much more respect for watchmakers now. Normally you do not need to fully disassemble this part. A good ultrasonic cleaning and a minuscule amount of watchmaker’s escapement oil on select pivots and the pallet will keep it running smoothly for years.
A is the star wheel/gear, it’s contact with the pallet (B) make that familiar buzz when you are using the slow speeds on your rollei. The duration is determined by pin C and how much it engages with a cam that sits on top of the shutter ( not pictured) This is how your 1/15th-1sec are achieved. As you can see, it doesn’t take much for this tiny mechanism to get gunked up.