摘要 |
The solenloid coils 26, 27 of a hydraulic spool valve may be selectively connected in series or parallel by a switch unit 101. The series connection is used during normal control operations, but if the valve spool 4 becomes jammed the unit switches over to the parallel connection. This quadruples the coil current, and the attendantly increased magnetic drive force enables the spool to shear through the contaminant particles entrained in the hydraulic fluid that are causing the jamming.
|