jam (on) the brake(s)
1. Literally, to quickly press on a vehicle's brakes to slow down or stop. He jammed on the brakes when he saw the child running into the street. You risk doing your car serious damage if you jam the brake without shifting down the gears.
2. By extension, to slow down or stop something one is doing. We had to jam on the brakes when we found out investors were pulling out of the company.
jam on the ˈbrake(s)
, jam the ˈbrake(s) on
make a vehicle stop very suddenly by operating the brakes with force: The car skidded as he jammed on the brakes.