Introduces Doosan DL220 The Shut-Off Valve Theory of Operation

 This page briefly introduces Doosan DL220 the shut-off valve theory of operation

Doosan Daewoo Excavator Operation and Repair Manual

Cushion Valve Operation Function The cushion valve absorbs any excessive peak pressure that maybe generated during initial movement of the steering wheel or during a change in steering direction. The cushion valve alsoprevents excessive high-pressure and shock that can result from steering load inertia.
Working Principle If a high-pressure oil is fed back to port R, it pushes spring(3)
and opens poppet(2). This operation directs the high-pressure oil to port L through the center hole in spool(12) and the check valve poppet in port L part. At the same time, oil reaches thepressure room of the plug through orifice (8). This operation closes the passage from port R to port L. This releases the pressure and prevents machine shock by intercepting oil. If a low-pressure oil flows, the cushion operation is not necessary. It is due to the speed of closing spool(12) is faster than the speed of opening poppet (2), therefore, the cushion valve does not work.

 

Doosan Diagnostic Tool DDT G2 SCAN( ECU ,DCU)Software 2016

Doosan DMS-5 (Doosan Data Monitoring System) Diagnostic Software V1.6.3