这辆车已开始向后滑动, 因为手闸不太灵.The car, whose handbrake wasn't very reliable , began to slide backwards.你戴上安全带,松开手闸.You put on your seatbelt and disengage the hand brake.手闸扳上时不可开车.Don't drive with the handbrake on....

“手闸”的英语可以翻译为：[医] hand switch ...