When pelleting cells, especially yeast or mammalian cells in flat-bottom vessels in a higher volume in a swing-out rotor, the pellet is not completely solid (depending on the application, it may not be possible to spin the cells at a higher speed to get a more compact pellet, because mammalian cells in particular are quite sensitive when it comes to centrifugal forces). The fact that the pellet is not completely solid means that when braking forces are too strong, the pellet could be remixed, leading to sample loss when the supernatant is discarded. Therefore, we recommend lowering the deceleration ramp (usually it is not necessary to shut off the brake completely) to keep the pellet from swirling up. The use of a vessel with a conical bottom shape can also help you get a tighter pellet, even when centrifuging at lower speeds.
Thus centrifuges with different acc/dec ramps offer users the option of adjusting acceleration and deceleration and optimizing their protocols quite easily.