737 - 800NG SFP auto brake
From my pal who drives them out of LGW for another carrier
The auto brake selector knob (rotary switch) has four settings: RTO (rejected takeoff), 1, 2, 3 and MAX (maximum). Settings 1, 2 and 3 and RTO can be armed by turning the selector; but, MAX can only be set by simultaneously pulling the selector knob outwards and turning to the right; this is a safety feature to eliminate the chance that the selector is set to MAX accidentally.
auto brake will engage upon landing, when -
auto brake selector knob (1, 2, 3 or MAX) has been set;
The thrust levers are in the idle position immediately prior to touchdown and the main wheels spin-up.
If the auto brake has not been selected before landing, it can still be engaged after touchdown, providing the aircraft has not decelerated below 60 knots.
To disengage the autobrake system, do one of the following -
(i) The autobrake selector knob is turned to OFF
(ii) The speed brake lever is moved to the 'down' detent position;
(iii) The thrust levers are advanced from idle to forward thrust (except during the first 3 seconds of landing); or,
(iv) Either pilot applies manual braking.
For shorter and wet runways, and/or in high crosswinds flight crews may prefer (or have to, if a SOP) to use the autobrake rather than use manual braking.