overdrive
/ˈəuvədraɪv; `ovɚˌdraɪv/ n
1 [U] mechanism providing an extra gear above the normal top gear in a vehicle （车辆中的）加速传动装置, 加速挡.
2 (idm 习语) go into `overdrive use the overdrive mechanism 使用加速挡
(fig 比喻) She always goes into overdrive (ie starts working very hard) before the holidays. 她总是在放假前特别努力.