您要查找的是不是：
- 单作用定位器single-acting positioner
- 双pair
- 作用action
- 双击double-click
- 双作用double action
- 双作用泵double-acting pump
- 双作用锤double-action hammer
- 双作用的difunctional
- 双作用缸double acting cylinder
- 双作用管double-purpose valve
- 双作用窝眼筒bi-action indent cylinder
- 双作用叶片泵Double-acting vane pump
- 双作用阀[电] double-purpose valve
- 双作用柱塞double-action plunger
- 双作用活塞double acting piston
- 双作用汽缸double-acting cylinder
- 双作用油缸two-way cylinder
- 双作用气缸double-acting cylinder
- 双作用弹簧double-acting spring
- 双作用常接触滚子旁承在货车转向架运用中存在的问题及建议Issues of using double action constant-contact roller side bearings on freight car bogies and suggestions
