Abstract Research purposes: Small － sized track maintenance machinery is the device to guarantee the good track state，and there is gap in the integral technology level between the small － sized track maintenance machinery in China and in foreign countries． Taking the YZ － Q type hydraulic rail straightener as an example，this paper illustrate how to ensure the the product ＇s practicability，novelty and portability on consideration of the product ＇s functional principle，appearance design，structure improvement and performance test for the purpose of providing the reference to the machinery design and performance test of the small － sized track maintenance machinery in China．
Research conclusions: For the great railways development，it is urgent to improve the small － sized track maintenance machinery in China． The hydraulic working principle of the rail straightener directly affects product performance，the structure design and the improvement have a direct impact on product availability and portability，the appearance design has a direct impact on product novelty，and the science of the performance test method directly affects the reliability of the product． The YZ － Q I － type rail straightener developed by reasonable design and structural improvement has the features of simple and compact structure，lightweight，safety，reliability，high speed，large load bearing capacity and convenient maintenance，and it is better than the similar products．
Zhang Hao． Fourth Survey and Design Institute of Morcalculation on Length of Parking Lines For Large － scale Track Maintenance Machine Railcar Unit ［J］． Journal of Railway Engineering，2000( 12) : 25 － 31．
2012, Vol. 29 
