| 摘要 |
<p>A valve push rod is made by welding a hollow shaft to base with a running surface. The shaft has a closed top end, and the base and/or the shaft end adjacent the base has >=1 groove, which permits the evacuation of the cavity in the shaft prior to electron beam welding the shaft onto the base. Welding closes the groove(s). The base is pref. provided with a projection entering the shaft and contg. a groove for evacuation of the shaft cavity. The shaft is pref. made of case-hardening steel, and the base is made of alloyed tool steel. Used e.g. in high speed diesel engines fitted in lorries. The device permits evacuation of the shaft cavity, but prevents the corrosive salts used in salt bath hardening from entering the shaft.</p> |
