Hydraulic Cylinder Precautions 1
Be sure to read before handling.
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ery are twisted due to external forces, etc.
In such cases, human injury may occur; e.g., by catching hands
or feet get caught in the machinery, or damage to the machin-
ery itself may occur. Therefore, the machine should be
designed to prevent such dangers.
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If a stationary object and moving parts of a cylinder are in close
proximity, personal injury may occur. Design the structure to
avoid contact with the human body.
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loose.
Especially when a cylinder operates with high frequency or is
installed where there is a lot of vibration, ensure that all parts
remain secure.
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When a driven object is operated at high speed or the load is
heavy, a cylinder's cushion will most likely not be sufficient to
absorb the impact. Install a deceleration circuit to reduce the
speed before cushioning, or install an external shock absorber
to relieve the impact.
In this case, the rigidity of the machinery should also be examined.
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When a cylinder is used as a clamping mechanism, there is a
danger of work pieces dropping if there is a decrease in clamping
force due to a drop in circuit pressure caused by a power outage.
Therefore, safety equipment should be installed to prevent
human injury or damage to machinery. Suspension mechanisms
and lifting devices also require for drop prevention measures.
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Measures should be taken to protect against human injury and
equipment damage in the event that there is a loss of power to
equipment controlled by air pressure, electricity, or hydraulics.
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When hydraulic pressure in a cylinder is zero, the driven object
will lurch at high speed if pressure is applied to one side of the
piston.Therefore, equipment should be selected and circuits
designed to prevent sudden lurching because there is a danger
of human injury and/or damage to equipment when this occurs.
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Design the system so that bodily injury and/or damage to
machinery and equipment will not occur when machinery is
stopped by a manual emergency stop or a safety device
triggered by abnormal conditions.
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Design machinery so that bodily insury or equipment damage
will not occur upon restart of operation.
When the cylinder has to be reset at the starting position, install
manual safely equipment.
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The products featured in this catalogue are designed strictly for
use in industrial oil hydraulic system applications. If the products
are used in conditions that are outside the range of pressure
and temperature specifications, damage and/or malfunction may
occur. Do not use in these conditions. (Refer to specifications.)
Consult with SMC if a fluid other than hydraulic fluid is to be used.
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Since hydraulic cylinders are not guaranteed for zero oil
leakage, it may not be possible to hold a stopped position for
an extended period of time.
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Use cylinders which can withstand the surge pressures
(maximum allowable pressure) generated in hydraulic systems.
(Refer to specifications.)
Inside cylinders, pressure may be generated that is higher than
the set pressure for the relief valve, e.g., internal pressure due to
load inertia or surge pressure when switching valves. Consider
these factors and determine the operating pressure so that the
pressure generated inside cylinders will be within the maximum
allowable pressure.
Pressure terminology used in this catalogue is defined as follows:
Nominal pressure: Pressure assigned to a cylinder for convenient
identification.It is not necessarily the same as the
operating pressure which guarantees performance
under specified conditions.
Maximum allowable: The maximum allowable value for the pressure that is
generated inside cylinders (such as surge pressure).
Proof pressure: Test pressure that the cylinder must be able to
withstand without lowering system performance
when returning to the nominal pressure.
Minimum operating: Minimum pressure at which a horizontally installed
cylinder operates with no-load.
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Selection
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The piston rod will be damaged if operated beyond the
maximum stroke. Refer to the stroke selection on pages 22
and 23 for maximum strokes.
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Operate within a range such that damage will not occur when the piston
having inertial force stops by striking the cover at the stroke end.
Take load factors and piston speed on page 21 into consider-
ation and determine the operability by referring to the chart
under “Selection Standards”.
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Warning
Warning
Caution
Hydraulic Fluid
Consult with SMC.
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Water/Glycol hydraulic fluids
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Series
CHS
Compatibility
28
