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Installation, Operation and Maintenance Manual
MAN 564_EAC Rev. 2
June 2020
Maintenance
Section 5: Maintenance
5.3
MHP Hydraulic Manual Override Maintenance
and Trouble Shooting
5.3.1
Operation
(see the attached operating diagram MAN 562-A)
The “MHP” hydraulic manual override and speed control unit is utilized, in connection with
the actuator hydraulic cylinder, for the manual operation and for the speed control during
the pneumatic operation of pneumatic double-acting actuators.
5.3.2
Manual Operation
Selected by the hand operated directional control valve (D) the operation (opening or
closing) to be performed.
Actuate the handpump (P).
The relief valve (Rm) prevents that the oil pressure delivered by the handpump exceeds
the set value so to not damage the valve or the actuator.
5.3.3
Remote Operation
To allow the actuator pneumatic operation the hand operated directional control valve (D)
has to be in its “REMOTE” control position: valve liver in its central position as shown by the
instructions plate.
Pneumatic operation
The oil flows from the hydraulic cylinder chamber, rear flange side, via the flow regulator
(Fa), the valve (D) and the flow regulator (FC), free flow direction, to the hydraulic cylinder
chamber, head flange side.
The exceeding oil volume, corresponding to the hydraulic cylinder piston rod, flows via the
flows regulator (Fr) into the oil tank (Ot).
The relief valve (Ra) prevents that the oil pressure, into the hydraulic cylinder, exceeds a
set value.
The flow regulator (Fa) allows the setting of the actuator operation speed in opening
independently from the actuator speed in closing.
Pneumatic closing operation
The oil flows from the hydraulic cylinder chamber, head flange side, via the flow regulator
(Fc), the valve (D) and the flow regulator (Fa), free flow direction, to the hydraulic cylinder
chamber, rear flange side.
The missing oil volume, corresponding to the piston rod of hydraulic cylinder, is sucked from
the oil tank via the check valve (Cv).
The flow regulator (Fc) allows the setting of the actuator operation speed in closing,
independently from the actuator speed in opening.