Tailgate Holding Valve - Wittke STARLIGHT Maintenance Manual

Location
On a unit equipped with a front-mounted main valve, the pack circuit dump valve is fitted next to the
main valve (see Figure 7-35). On a unit equipped with a side-mounted main valve, the pack circuit
dump valve is installed on the lower section of the front inside wall (see Figure 7-36).
Figure 7-36 Dump valve (shown on unit with side-mounted main valve)

Tailgate Holding Valve

The tailgate locking mechanism is equipped with hydraulic safety systems that prevent accidental
unlocking of the tailgate during operation. One of the systems is the velocity fuse with the "power
bleed" and the other is the holding valve.
The spool inside the tailgate section of the valve is designed in such a way that it will allow pressure to
pass through it each time the pressure is building up in the hydraulic system (i.e. when the packer is
working). The pressure "burst" goes to the holding valve into port "D1" and then out to the cylinder
via port "U1". This will keep the tailgate cylinders pressurized and the tailgate closed when packing
material.
Location
The tailgate holding valve is located on the underside of the body, near the tailgate.
Hydraulic System 115