| Noisy Pump |
Cavitation |
Specify a larger intake pipe. |
Use a larger suction strainer
Use lower viscosity oil. |
|
Restricted Suction |
Suction needs to be at least 50% larger
than the discharge
pipe. Place the pump not more than 24 inches above the
oil level.
|
Clean the suction strainer |
|
Air leak at intake |
Keep suction lines simple. |
Pour oil over the joints when
The pump is running and spot
Joint where pump runs quietly. |
|
Air leak at intake shaft packing |
Use flexible drive coupling with Stiff
tank top for rigidity. |
Lubricate or renew packing.
Accurately align pump shaft. |
|
Air drawn into system from tanks |
Place suction and discharge pipes
on opposite sides of baffle plate.
Check oil requirements of circuit against delivery of
pump.
|
Raise oil level in the tank.
Discharge below oil level.
Does oil have an anti-foam additive? |
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| Noisy Pump |
Worn valves, vanes
Pistons, gears, etc. |
Use filters as often as practical |
Renew worn parts
Clean filters. |
|
Sticking valves
Or vanes |
Incorporate Filter in system. |
Check for impurities or metal particles
in oil. Clean filters. |
| Excessive heating of pump |
Internal pump leakage |
Use pumps well below their upper pressure limits. |
Renew worn parts, such as gears, vanes,
pistons, valves, etc. |
|
Internal leakage caused by thin oil |
Specify closer tolerances and finishes,
or higher VI oil.
Increase cooling capacity.
|
Use heavier bodied oil.
User higher VI oil.
Check pressure relief valve setting.
Check pressure relief valve for leaks. |
|
Insufficient clearance of moving parts |
Check assembly of pump parts. |
|
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Pump flow low |
Pump parts worn Out or system bypassing Oil. |
Check orifice in relief valve
|
Renew worn parts |
|
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Erratic & sluggish Operation |
Oil viscosity too high. Not enough Horsepower. |
Check needed power input – HP goes up with very high
viscosities. |
Use lower viscosity oil. |
|
|
Pump low pressure |
Short circuit in Pump or system is Bypassing |
|
Check seal between inlet and outlet ports of pump. Check
orifice in relief valve |
|
|
Low or no pressure In the system. |
Relief valve jammed Or orifice plugged |
Reset pressure setting after |
cleaning relief valve. |
|
 |
Low oil |
Provide site glass. |
Add oil. |
|
|
Fluctuating PSI |
Air or water in System, No back Pressure. |
Provide 5 – 10 lbs. Back pressure relief valve (foot
valve), on Return line. |
Check seals and pipe connections. Check for jams or
obstructions in System (collapsed hose?). |
|
|
Erratic movements |
Insufficient oil in System or Improper kind of Oil.
Water or air Present. |
Check oil requirements of total cycle. Provide site
gauge. |
Check vent valve. Check oil level. Test oil. |
|
|
High pressure Below expectations |
Relief valve not functioning Properly. Internal Pump
leakage, |
Check capacity of spring (if direct operated). Use
proper viscosity oil. |
Check poppet for sticking and Spring for proper
adjustment. Use proper oil. |
|
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NOW! Call or email us now. (Click here
for our contact page). |
|
High pressure Below expectations |
Excessive frictional loses in system. Oil Velocity too
high |
Use as few pipe bends as possible. Adhere to ideal
radius of pipe and tubing bends. Area of ports, holes |
Tubing and piping to be consistent With an oil velocity
of 15 fps on Pressure lines. 10 fps on return lines. |
|
|
Frequent leaks in Lines
|
Vibration in machine. |
Design in more brackets and |
Fasten oil lines securely. more supports |
|
|
Overheating of oil (efficient normal Operating temp is
About 130° 140° Degrees F). |
Too much oil blowing over the relief valve. (Pump too
large for the system)
|
Pump capacity to be at least 10 To 15% larger than
requirements. |
Check relief valve for pressure and Leakage. Check
pressures at which pump should operate. Add heat
exchanger. |
|
|
|
Insufficient oil or oil level too low. |
Increase capacity of oil tank To at least 34 times the
pump. |
Add oil |
|
|
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Highpressure help too long. |
Use small pump for high pressure |
And high volume pump for low pressure. |
|
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Oil too light
|
Specify correct SSU oil. |
Use heavier oil.
|
|
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Obstructions or restrictions to flow of |
Avoid sharp bends in pipelines especially in copper
tubing. |
Check position of control valve For neutral location and
overloads. |
|
|
|
Oil in pipeline |
Specify ideal bending radius. |
Pump parts may be worn. Check backpressure valve for
high pressure. |
|
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Excessive leakage In system (internal). |
Oil too light, valves Pumps worn out. |
Specify correct viscosity & correct Viscosity. |
Check clearances. Use heavier oil If leakage is still
excessive. |
|
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Irregular, erratic or Uncertain feeds. |
|
Check control valve for proper Positioning. Check
linkage and cam Adjustments |
Check for excessive internal leakage. Check kind of oil
used use recommended oil. Check external pilot pressure
if |
|
|
Slow acting machine |
Starting temperature of Oil is too cold. |
Provide immersion heaters. |
Set controls so that oil is blown Across relief valve
until it heats. |
|
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|
Oil is too heavy, causing Excessive frictional
Resistance in system. |
Increase size of plumbing. |
Use lighter oil. |
|
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Jerky operation of Working cylinders, Motors, etc. |
Friction in seals Friction in ways. |
Provide pressure at both ends of Cylinder. For servo
systems, specify “Low Friction” type seal. |
Check oil level, may be too low. See that packing is not
binding. Check for worn or scored rods, Seals, and
broken piston rings. |
|
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NOW! Call or email us now. (Click here
for our contact page). |
|
Jerky operation of Working cylinders, Motors, etc. |
Air in the system |
Provide bleeder port in the top |
Bleed the cylinders. cylinder. |
|
|
Rapid traverse of Reversing valve Troubles. |
|
Springs of check valve too weak, recalculate. Provide
dashpot or Springs in ends of valve. Floating Spool
mounted horizontally. |
Check for broken springs. Valve plunger depressed too
far. Cams and / or rollers worn. Valve Remaining
partially open. |
|
|
Acceleration too Slow |
|
Taper on spool too long and gradual. Use check valve to
bypass. |
Check relief valve setting. |
|
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Acceleration too Fast |
|
Taper on spool too short. Use metering valve in
addition to dashpot. |
|
|
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3 and 4way valve troubles. Overheating of Solenoid
operated Valves; indicated by Hum or buzz. |
|
With plunger or spool in home Position, solenoid should
have completed stroke and rest dead Provide clearance
between solenoid link and valve plunger (1/64”). |
Excessive wear of spools or body, Broken springs. Leaky
seals. Binding resulting from varnish costing. Replace
valve. |
|
|
Check valve trouble Flow Control |
|
Mount in a vertical position |
Check condition of valve seat. If Worn or ball of poppet
is in poor Condition, reseat new ball.
Replace valve. Pressure compensator binding, |
|
|
Flow Control Troubles Metering valve not Functioning
properly |
|
Provide lock to set position for desired feed. |
Pressure compensator binding, caused by dirt. Plungers
worn.
Clean orifice, polish spool.
Dirt lodged in eccentric grooves Or orifice. |
|
|
Metering valve not Functioning properly |
|
Provide lock to set position for desired feed. |
Dirt lodged in eccentric grooves Or orifice. |
|
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Needle valve will not Control or shutoff. |
|
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Needle valve worn; regrind and Relap or replace. |
|
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Fluctuating pressure Of relief valve |
|
|
Relief pressure control spring broken / worn. Check for
proper adjustment.
Clean orifice.
Check pilot cone.
|
|
|
Pressure reducing |
|
Drain line to be open directly to Tank; do not connect
to return line |
Spring adjustment fault. Drain line closed. Broken
springs. |
|
| Get started
NOW! Call or email us now. (Click here
for our contact page). |
|
Solenoid Failures: |
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|
|
Solenoid Failure |
When a solenoid is held at inrush current for an
extended period of time, the solenoid overheats and
eventually burns out. The heat produced by the solenoid
melts the nylon. This melted nylon flows in around the
plunger and causes it to stick in some positions. This
mechanically blocks the valve from shifting. |
Cause of failure includes: |
|
|
|
Melted Nylon |
|
1. Excessive force needed to shift spools |
|
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2. Both solenoids energized at the same time on a double
solenoid valve. |
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3. Cycle rate too high – not cooling properly. |
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4. Voltage too high or too low. |
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Solenoid Buzzing |
When the solenoid plunger is kept from bottoming out,
the solenoid will have a tendency to buzz. This buzzing
is created by the pulsating AC current magnetism being
opposed by a hydraulic spool force and a spring force
causing the plunger to move in and out |
Cause of failure include: |
|
|
|
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1. Excessive force required to shift the spool |
|
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a. Contamination adds to spool shifting forces. |
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b. Valve spool silting |
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c. Flow specification of valve being exceeded. |
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d. Excessive spring centering or spring offset force. |
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2. Low Voltage. |
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3. Damaged coil |
|
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4. Split Solenoid laminations. |
|
|
|
Brittle Solenoid Leads |
The continual use of the solenoid over a period of time
will leave the wire insulation brittle. This creates
the possibility of insulation and / or wire breakage
which may lead to shorting out of the solenoid |
Cause of failure include: |
|
|
|
|
1. The leads are affected by heart generated by the
solenoid. This situation is aggravated by high ambient
temperatures. |
|
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2. Type of hydraulic fluid may be eating / affecting the
insulation. |
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|
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3. Cutting fluid used by the machine could be destroying
the insulation. |
|
|
|
Solenoids Exposed to Fire Resistant Fluids |
Exposure of solenoids to fire resistant fluids such as
Phosphate Esters, will cause shorts between the coil
windings. These fluids will also dissolve the coil’s
varnish and solenoid’s black paint. The fluids will
also affect the lead wire insulation by causing it to
become spongy and eventually drop off. This condition
can be avoided by purchasing solenoids or coils that are
compatible with the caustic fluids. |
Cause of failure: |
|
|
|
|
1. Chemical reaction with the solenoid. |
|
|
|
Solenoid Failure – Coil burns Out |
Continuous inrush current melted nylon |
Causes of failure include:
1. Mechanical blockage
2. Low line voltage
3. Excessive ambient temperature
4. Excessive cycle rate.
5. Excessive / high line voltage. |
|
|
|
Solenoid failure – Shorting |
|
1. Coolants containing metal chips
2. Voltage transients
3. Fire resistant fluids |
|
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|
Solenoid Failure – Mechanical Destruction |
|
1. Over voltage
2. Excessive cycle rates
3. Overzealous mechanic. |
|
|
|
Shorted Solenoid |
A solenoid used in or near water based coolants that are
saturated with fine metal particles is susceptible to
shorting between the coil lead wire junctions |
Cause of failure include:
1. Soaking of the coil with coolant. |
|
|
