目前、工务系统大量地使用齿条起道机。齿条起道机的降落装置,由于操作程序较多,使起道机难于快速撤离线路。这种结构的起道机极易出现“落两牙”的情况,此时、欲使齿条落下非常困难。在列车临近时,会因不能撤离线路,导至与列车相撞。起道机的这种“挡道”事故,在工务系统各种事故中占很大的比重,严重地影响着行车安全。因此、设计制造起道机速降装置,消灭起道机“挡道”事故, At present, the public works system uses rack and pinion machines extensively. Rack gear from the landing device, due to the operating procedures more difficult to take the road to withdraw from the line quickly. This structure of the starting machine prone to “fall two teeth” situation, at this time, want to make the rack down very difficult. As the train approaches, it can not be pulled out of the line and lead to a collision with the train. This kind of “road blocking” accident of the road machine occupies a large proportion of various accidents in the public works system, which seriously affects traffic safety. Therefore, the design and manufacture of speed reducer device from the road to eliminate the road from the “Road” accident,