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- Excellent performance and quality guaranteed by strict material selection,
improved heat treatment techniques and high precision machining technology.
- Nachi hydraulic pumps have been designed to operate at the lowest
noise level possible.
Installation and Maintenance
Note the following when Nachi hydraulic pumps are installed and at the
time of maintenance.
- The eccentricity between the motor drive shaft and pump shaft must
be kept within 0.05mm ( 0.002 in ). The eccentric angle between them
must be maintained within 1 degree. Be sure to use flexible coupling
when linking a drive motor with a pump.
- When a belt, gear, or chain is used to drive a hydraulic pump, care
must be taken that the radial or the thrust load will not be applied
to the pump shaft. If this type design is necessary, install a device
to assure the pump shaft of no load ( bending force ) applied at right
- For safe installation, use a pump base which has sufficient rigidity.
- Each Nachi hydraulic pump has its rotating direction fixed. Prior
to the start of regular operation, check the rotating direction of the
pump by referring to the model code on the nameplate or the arrow mark
( on the pump body ) showing proper rotating direction. The normal rotating
direction of Nachi hydraulic pumps is clockwise as viewed from the shaft
- Hydraulic pumps with an external drain should have the drain piping
connected directly to the reservoir at a point below the oil level.
The piping should be sized to keep the back pressure below 4.3 PSI.
- When a steel pipe is used for the inlet and outlet piping of a hydraulic
pump, be careful that an abnormally large force is not applied to the
- The length of the joint made with the use of key fitted in the keyway
across the pump shaft should be over 2/3 the coupling width. For safe
and positive connection, select a coupling having a size suitable to
- When each key is driven into the keyway, do not apply an excessively
large force to the shaft. Be sure to use a coupling puller to remove
the coupling. Otherwise, the inner parts may be damaged. Never strike
the shafts of both the motor and pump when the coupling is removed.
- Install each hydraulic pump in a manner so that the interior of the
pump may be kept filled with oil even while the pump is not being operated.
- An air bleed-off valve should be installed for an hydraulic circuit
which does not require air bleeding at the time the pump is started.
- Be sure to use bolts specified by this company for use with Nachi
hydraulic pumps. We recommended the use of bolts with a torque rating
of more than grade 12.9.
Hydraulic Oil Control
- To keep the hydraulic oil clean, provide a suction filter with a
mesh size of 100~150 at the inlet suction port of the pump.
- To increase pump life, a 25u filter is recommended.
- Please contact Nachi before using any fire resistant fluids.
The following technical terms used in this catalog have the meanings cited
- Rated Pressure:
Refers to the pressure under which the hydraulic pump can be operated
- Maximum Operating Pressure:
Refers to the pressure to which the pump can be operated within 1/10
of the cycle time or within 6 seconds at the longest.