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Installation, Operation and Maintenance Manual
MAN 564 Rev. 6
June 2020
Operation and Use
Section 3: Operation and Use
Figure 21
Emergencency manual override
Figure 22
MHP hydraulic manual override
The MHW - MSJ jackscrew manual override can be supplied for model up to 3. The override
is mounted on the left side of the actuator, the jackscrew end is screwed into the guide
block. A bronze split screw nut is mounted inside the body. By rotating the engagement
lever, the screw nut is engaged with the jackscrew. When the screw nut is engaged with the
jackscrew manual operation follows by rotating the body of the screw container by a lever
(for MSJ models) or by a hand-wheel (for MHW models).
The MHP hydraulic manual override is used to manually operate the actuator in lack of air
supply. It also allows to accurately adjust the actuator operating times, independently in
opening and in closing, by way of the hydraulic regulators which work on the oil flow from
one chamber to the other of the hydraulic cylinder during pneumatic operation. Moreover
it permits a smooth angular speed all along the stroke. During manual operation the flow
regulators are by-passed to make the force on the handpump lever easy. The MHP unit
consists of a hydraulic cylinder mounted directly on the actuator. The piston rod end is
screwed into the guide block. The compact hydraulic control unit consists of a handpump,
directional control valve, oil tank, relief valve and two unidirectional flow regulators. The
directional control valve has three operating positions: “remote”: the actuator is operated
by pneumatic supply; “to open”: the actuator operation is opening by handpump. On
request the hydraulic manual override type MHP2 (double handpump version) can be
supplied, which allows the remote control to automatically override manual operation.
