CMX Puesta en Marcha y Trouble Shooting
CMX Puesta en Marcha y Trouble Shooting
CMX Puesta en Marcha y Trouble Shooting
Directional Controls
T DR PS LS P PS DR
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Support Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Chart 1 – Instability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Chart 2 – Metering/Feathering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Appendix:
3
Support Equipment
4
Start-Up Procedure & Check List
The following steps have been designed as a guide in 10 During Step 9, repeat Step 8.
starting up hydraulic systems in which one or more banks of
CMX valves are used. It is to be used as a step by step 11 Bring the engine up to half throttle and the oil
sequential check list to ensure trouble free operation of the temperature to 120°F (50°C).
hydraulic system prior to shipment.
12 Operate all functions to get any remaining air out of the
1 Ensure all lines, fittings and the reservoir have been system. It may take several cycles to remove all of the
properly cleaned prior to their installation on the air. During this step care must be taken to ensure these
vehicle/machine. Reference Service Drawings operations are performed at a “no load” condition. As
I– 1221–S and I–3998–S. required, bleed any remaining air out of the system by
cracking a fitting at the highest point in the vehicle.
2 Ensure the cases of all piston pumps and motors are
filled with oil. 13 Recheck reservoir level and oil condition to ensure there
is no evidence of air or other undesirable characteristics.
3 Install pressure gages at critical test points. Normally 5
gages – 2 high pressure (0 to 5000 psi/0 to 350 bar) and 14 Bring the engine up to full throttle and the oil temperature
3 low pressure (0 to 600 psi/0 to 45 bar) – are the to anticipated operating temperature to ensure proper
minimum number required to enable satisfactory functioning of the load sensing signals at system
measurement of the various pressure line, pilot line, load operating conditions. Note, it may be difficult to bring the
sensing line and drain line pressure levels during system unloaded system up to this temperature as it is a load
operation. sensing system. However, our experience has proven
that it is important to bring the start up system operating
4 Fill and check the reservoir to ensure proper oil level and temperature as close as possible to normal operating
that there are no visible leaks or sources of unwanted air temperature to ensure proper functioning of the load
entry. sensing function.
5 Start engine/motor and bring up to idle speed. 15 Continue operation of all functions while observing for
smoothness of operation, jerky motions, noise and any
6 Flush the system. This can be done by short circuiting other undesirable characteristics that will need to be
one high flow demand actuator with a filter containing addressed.
“V03” filter media to meet the cleanliness level of
15/13/11 for CMX systems. Refer to Publication 561 for 16 Continue operation of all functions to check functioning
guidelines on establishing cleanliness levels and filtration of pump controls.
recommendations. Operate that function for a minimum
of 20–30 minutes to ensure a minimum of 10 passes of 17 Shut down the engine/motor.
total system oil volume through the filter. Remove the
flushing filter and allow the system to warm up to 18 Change all filter elements and install new elements with
approximately 120°F (50°C). a minimum media rating of “V03”.
7 Extend all cylinders, one at a time, bleeding air as 19 Restart the engine and let the oil circulate through the
required. system at engine idle speed.
8 During Step 7, recheck reservoir level to ensure it is at 20 Shut down the engine and take an oil sample to ensure
the proper level; observe the oil condition to ensure their proper cleanliness level based on the highest system
is no sign of air or other undesirable characteristics; and, operating pressure level and the recommended
to ensure there are no signs of vortexing in the reservoir. cleanliness level of 15/13/11 for CMX systems.
Reference Publication 561 for background on
9 Retract all cylinders, one at a time. establishing cleanliness levels and filtration
recommendations. See Publications 562, 559 and 559A
for guidance in taking oil samples and obtaining a written
analysis of the oil sample.
5
Trouble Shooting Hydraulic Systems
6
Quick Reference Guide
1 – INSTABILITY Lurching, hammering, chattering, 1.1 Low frequency hunting 1.1.1 thru 1.1.3
low frequency hunting, vibration,
1.2 Chattering when lowering load against 1.2.1 thru 1.2.3
etc.
external counterbalance valve
1.3 Instability with solenoid coil buzzing 1.3.1
1.4 Engine pulsing at corner horsepower 1.4.1
1.5 Excessive acceleration 1.5.1
1.6 Load interference 1.6.1
7
Chart 1 – Instability
8
Chart 2 – Poor Metering/Feathering
9
Chart 3 – Function Movement
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3.5 Problem: 3.8 Problem:
Function slows down when function demanding lower System instability while accelerating a high inertia load such
pressure is used. as a swing function.
Solutions: Solution:
1. Modify circuit to redistribute valve functions to This condition can occur when the load overruns the flow
eliminate the interference when these functions are available from the meter–in flow control spool. It is
operated simultaneously. resolved by changing to a pressure control spool.
2. If possible, change from the existing pump to either a 3.9 Problem:
larger pump or to a multiple pump system. Poor overrunning load velocity control.
3. Modify circuit to incorporate an anti–saturation device.
Solutions:
If the system is already using electrical actuation, this
can easily be accommodated in the controller. If the 1. Ensure the correct meter–out element is being used
system is using hydraulic actuation, and, it is not and/or is not sticking.
feasible to change to electrical actuation, then change 2. If the valve is hydraulically controlled, ensure the pilot
the meter–in spool to a pressure control meter–in pressure is at the correct setting. Or...if the valve is
spool. electrically controlled, ensure the threshold current
4. If the above does not resolve the problem, then a signal is correct.
hydrostat (compensator element) will be required to 3. Change to a lower gain meter–out poppet if the
limit flow in the cylinder line. resulting increased pressure drop can be accepted.
3.6 Problem: 4. If this occurs in a high flow condition, check to ensure
Poor response when 2nd or 3rd function is actuated. that maximum required flow is achieved just before
the end of the lever stroke in order to obtain maximum
Solution: resolution.
This indicates insufficient pilot flow. The problem is 5. Consider use of a counterbalance valve at the
resolved by either going to a larger pilot pump or by actuator.
using an accumulator in the pilot flow circuit. A general
rule of thumb, there should be a minimum of 4 gpm (15 3.10 Problem:
lpm) pilot flow, depending upon the number of functions. Actuator velocity is either too high or too low.
3.7 Problem: Solutions:
Load drift. 1. Confirm that the pilot command signal and meter–in
Solutions: spring are properly matched.
1. Reconfirm port relief is set at the correct pressure 2. Check engine speed.
setting. The maximum load pressure should not 3. Check pump output flow.
exceed 80% of port relief valve setting.
4. Confirm the valve has received the proper command
2. Check to ensure meter–out element has not stuck in signal.
the open position.
5. Confirm the meter–in spool is correct.
3. Check to ensure the load drop check valve is properly
6. Confirm the meter–in spring has the correct setting.
seating.
7. Confirm the meter–out element gain is correct.
4. Check to ensure the HRC drain pressure is not higher
than the required CMX pilot drain line pressure. If this 8. Confirm the pressure drop across the meter–out
is the situation, then the valve will effectively be in the element does not exceed rated conditions.
float position and will not hold the load. This condition 9. Confirm the port relief valve setting is correct.
is corrected by reducing the back pressure which is
accomplished by plumbing the HRC tank return line 10.Confirm that the load sense bleed orifice is not too
directly to the reservoir. large compared to the load sensing dampening orifice
and thus prevents the true load pressure from being
fed back to the pump.
11.Confirm the lines are not undersized and causing low
velocity at the actuator.This can occur with long line runs.
11
Chart 4 – System Problems
General symptoms: 3. Check to ensure oil is available from the tank line
when the actuator is cavitating. If the tank line
System runs hot, exhibits symptoms of cavitation, is noisy or
pressure is below the setting of the back pressure
exhibits general sluggishness.
valve oil will be missing in the tank line. This can be
4.1 Problem: corrected by installing a pressure reducing valve from
the pump outlet line to the tank line before the back
System is running hot. pressure valve. The pressure setting of the pressure
Solutions: reducing valve should be just below cracking
1. Check system relief valve and port relief valves to pressure. This will then add flow from the pump outlet
ensure they are a minimum of 300 psi (20 bar) higher to the tank line whenever tank line pressure is below
than pump compensator or pump pressure limiter the setting of the back pressure valve.
setting. 4. Confirm reservoir oil level is not low.
2. Check to ensure there are no obvious leakage points. 5. Review the reservoir design to ensure there are no
3. Check individual components for excessive internal restrictions to good oil circulation.
leakage. Replace as necessary. 4.4 Problem:
4. Confirm the pump load sense P is correct. This Aeration noise.
should be done at 40% or greater displacement.
Solution:
5. Check to confirm the reservoir oil level is not low. Entrapped air may remain in the system. It will be
6. Confirm the hydraulic system cooler is adequately necessary to bleed the system to purge this air. Refer to
sized, or not bypassed. “Start–up Procedure” steps 4 thru 15 for guidance.
7. Ensure the system oil does not have excessive 4.5 Problem:
entrained air. Solenoid humming or buzzing.
4.2 Problem:
Solution:
Pump is noisy. Check to ensure the Pulse Width Modulation frequency
Solutions: is 100 Hz minimum. Note, if you are using the DMX
controller developed in Scandinavia for use with CMX
1. Check pump inlet lines and connections for signs of
valves, in some systems the best results are obtained
air entry and eliminate any areas of air entry.
with an 85 Hz PWM signal.
2. Check pump inlet lines to assure proper flow
4.6 Problem:
conditions to avoid cavitation.
System response is sluggish.
3. Check to confirm the reservoir oil lever is not low.
4. Review reservoir design to insure proper pump inlet Solutions:
conditions exist. 1. Check vehicle start–up procedure to ensure hydraulic
4.3 Problem: system is properly warmed up prior to hydraulic
system operation.
Actuator deceleration noise and/or spongy stop of the
2. Check load sensing line to ensure it is not too small.
cylinder.
As a minimum, line size should be 3/8 inch rubber
Solutions: hose.
1. Increase setting of back pressure relief in the tank 3. Check to confirm the load sense dampening orifice is
line. While the setting required will vary from not blocked or restricted.
application/installation to application/installation, a
4. Check to confirm the piston pump(s) are not operating
general rule of thumb is that the setting should be at
outside of their viscosity range.
least 65 psi (4.5 bar).
5. Confirm that the load sense bleed orifice is not too
2. In the majority of cases increasing the back pressure
large compared to the load sensing dampening orifice
setting will not be sufficient to prevent cylinder
and thus prevents the true load pressure from being
cavitation and action will be required to install an
fed back to the pump.
anti–cavitation module on the CMX valve.
6. Check to confirm there is no entrapped air. If there is,
bleed the system as required, reference “Start–up
Procedure” steps 4 through 15 for guidance.
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Typical CMX Electrohydraulic Valve Section
Pilot Relief
Electrohydraulic
Reducing A"
Valve Spool Solenoid
B"
Solenoid Pilot Supply
Passages
Load Sensing Valve Inlet Gasket
Vent
Check Valves Meter-in Port
Spool Meter-in
Chambers
T DR PS LS P PS DR
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Typical CMX Hydraulic Valve Section
Load Drop
Check
Load Pilot
Sensing Relief
Check
Valves
Pilot
Pressure
Port C2"
Pilot Meter-in
Pressure Vent Valve Gasket
Meter-in Chambers
Port C1" Inlet Port
Spool
B
A
C1 C2
DR T LS P DR
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CMX Port Locations
Optional
cooling
Auxiliary pilot
port “K”
Load sensing port drain port
(.5625–18
(.5625–18 (.5625–18 UN
UNF–2B
Outlet port (1.3125–12 UN–2B UNF–2B –2B
Straight thd–
Straight Thd – SAE Type) Straight thd Straight Thd – SAE Type)
SAE type)
SAE type
Optional
deceleration
port “EP”
(.5625–18
UNF–2B
Straight thd
SAE type)
15