Midland SPD-6, Operation, Parts & Service Manual

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Model SPD-6
Overview
This section provides general steps to follow if you observe undesirable system conditions. Follow the
steps until you solve the problem. Some of the items are system specific. Always observe the safety
precautions in the
Introduction section.
W
Warning
Unintended movement of the machine or mechanism may cause injury to the technician or bystanders.
To protect against unintended movement, secure the machine or disable/disconnect the mechanism
while servicing.
Electrical troubleshooting
Item Description Action
Motor operates at one
displacement only. Control coil failure Measure resistance at coil pins.
Proportional controls: Resistance should be 14.20 Ohms (24V) or
3.66 Ohms (12V) at 20°C [70°F].
Two-position controls: Resistance should be 8.4 Ohms (24V) or
34.5 Ohms (12V) at 20°C [70°F].
Replace coil if necessary.
Erratic motor function Electrical connection to motor is intermittent. Disconnect connector, check wires and terminals, reconnect wires.
Check terminals for corrosion and correct position.
Sluggish operation
Check Cause Corrective action
1. Control orifices Blocked or restricted orifice may cause sluggish
response. Orifices installed in the wrong locations
may cause PCOR control to be sluggish. Remove, inspect and clean all orifices. Ensure the
appropriate orifices are installed and in the correct
location.
2. Threshold setting (proportional
controls) Inappropriately high or low threshold setting may
shift the motor at the wrong time. Check threshold setting. Adjust if necessary.
3. Control spool A sticky control may cause sluggish response or no
response. Clean and inspect the control spool. Replace if
necessary.
4. Pressure compensator setting Low pressure compensator setting may shift motor
to maximum displacement at lower pressure. Check pressure compensator setting. Adjust if
necessary.
5. Control input signal An improper or erratic input signal to the control
may cause sluggish response. Check input signal and correct if necessary.
6. Internal leakage Excessive leakage will cause lower charge pressure
and affect performance. Install loop flushing defeat option and measure case
flow. If case flow is excessive, motor may require major
repair. Contact your Danfoss authorized service
center.
System operating hot
Check Cause Corrective action
1. Oil level Insufficient hydraulic fluid may cause overheating. Fill reservoir to proper level.
2. Heat exchanger Blocked heat exchanger or low air flow may cause
system overheating. Check temperature upstream and downstream of heat
exchanger. Clean, repair, or replace heat exchanger if
necessary.
3. Loop flushing flow Restricted orifice in loop flushing cartridge reduces
flow. Measure case drain flow. Clean or replace orifice
cartridge.
Service Manual H1B 060/080/110/160/250 Bent Axis Motors
Troubleshooting
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