Fall commonly block after be being used in speed to reduce, when the driving force of engine feels insufficient. If speed falls to fall again,blocking is a very easy thing, need to step on next clutch only, block speed change dial gently low block can. But, if the car is in high speed travel, wanting to be operated very pliably is not a very easy thing. Because the car is when high speed travel,this is, the synchronous rotate speed of gear and engine is very fast, if want to facilitate,fall block, gear comparing should greaten, engine there must want to turn a few rounds more, namely the gear there must choose engine to cooperate lesserly. And when clutch is loose, as a result of the car tremendous and inertial make the gear that receives transmission shaft repeatedly still rotates with higher rate, at this moment because engine turns into slow fast circumgyrate, in gear-box also slow subsequently with engine connective gear, six to one of rotate speed of both sides gear, cannot synchronous photograph join. Right now if according to normally method falls block, will block very hard dial keep out.

Want to be changed easily keep out, with respect to the rotate speed that must increase engine, made immediateness transmission shaft the gear rotate speed there. The method that rise uses the time that moves neutral to combine clutch namely, cheer a rotate speed with raising engine for nothing, dissection clutch again next, dial gearlever low block, combine clutch, finish fall block. This kind of method says to regard as " double foot clutch law " . The program of law of this one party sums up as follows: (1) accelerator is unlocked in travel; (2) step on next clutch; (3) turn into neutral, put clutch; (4) cheer the door for nothing; (5) step on next clutch; (6) dial keep out; (7) put clutch and cheer at the same time.

Actually this is planted " double foot clutch law " when there is synchronized in original car gear-box, it is the skill that each drivers must master. And present car uses synchronized generally, fall in high speed only so the ability when blocking is necessary to use " double foot clutch law " . Should fall in travel of the high speed on the freeway especially when blocking, if step on brake at the beginning, in case brake is ineffective can have risk, if stop a machine by cutting off the power is too effective,be afraid of last stop to undercarriage scorchs and create decline appearance again. Accordingly, borrowing engine power to fall speed with this method horary the 50 speed to 60 kilometers step on brake again the meeting is safer.