Boom Anti-Fall Valve; At Neutral Position Of Boom Section - Kubota U20-3 Workshop Manual

U20-3, U25-3 WSM Hydraulic system (Mechanism section)
e. Boom anti-fall valve

(1) At neutral position of boom section

The hydraulic oil at port B (cylinder rod side) is shut off.
The hydraulic oil at port A (cylinder bottom side) flows through the passage C and poppet "d" into the
chamber Z. Now the anti-drift poppet gets closed, which prevents the boom from falling.
Port A
Port B
Port T
Pb
Pa
Section A-A
Passage c
Poppet d
Section B-B
Chamber Z
IV-M-17