Solenoids are the heart of control systems in power hydraulics. They are responsible for switching solenoid valves, and thus for the direction, pressure, and flow of hydraulic oil in the machine. Although it is a relatively small component, its failure usually means one thing: immediate and costly downtime of the production line or construction machine.
When a solenoid burns out, quick replacement is a priority. However, how can one avoid mistakes when choosing a replacement and what parameters should be considered to ensure the new solenoid operates flawlessly for years?
4 key parameters for solenoid selectionFor the new component to work with your directional control valve or valve, you need to verify a few basic values. You will usually find them engraved or printed on the housing of the old solenoid.
1. Voltage and current type (V)
This is an absolute basic. Solenoids operate on different supply voltages. Connecting a 12V solenoid to a 24V installation will burn it out in a fraction of a second, while a 24V solenoid in a 12V installation will not generate enough magnetic field to move the valve spool.
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Typical DC values (direct current): 12V, 24V (most popular in mobile power hydraulics and agricultural machinery).
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Typical AC values (alternating current): 110V, 230V (common in stationary industrial applications).
2. Inner diameter and length (Mechanical dimensions)
Even if the electrical parameters match, the solenoid must physically fit onto the valve stem (tube). Accurately measure with a caliper:
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The diameter of the inner bore (e.g., 13 mm, 18 mm, 22 mm).
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The total length of the solenoid, so that the retaining nut can securely grip the thread at the end of the stem.
3. Power (W)
Solenoid power directly translates to the force with which the valve core is attracted. In systems with high operating pressure or with thick oil, higher power solenoids are required to overcome the spool's resistance. When replacing, the substitute should have power equal to or slightly higher than the original.
4. Type of electrical connection (Plug)
The method of connection to the machine's installation must be compatible to ensure tightness (often IP65/IP67 protection class). The most popular standards include:
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DIN 43650 plugs (EN 175301-803) – type A (wide), type B (narrow),
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AMP Junior Timer – very popular in automotive and mobile machinery,
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Deutsch DT04 – connectors with increased resistance to harsh conditions,
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Flying leads.
Why do hydraulic solenoids burn out? Diagnosing the problem
Simply installing a new solenoid from a catalog is often treating the symptoms, not the cause. Electromagnets most often fail for two reasons:
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Mechanical blockage of the valve spool: If the oil in the system is contaminated, dirt can block the spool. The solenoid receives a signal and current, attempts to move the blocked core, which causes immediate overheating and melting of the copper winding's insulation. Before installing a new solenoid, make sure the valve stem moves freely!
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Continuous operation above parameters (ED): Each solenoid has a specified duty cycle, known as the ED factor (usually ED 100%, meaning continuous operation is possible). Poor valve cooling or operation in extremely high ambient temperatures drastically shortens its lifespan.
Summary
Solenoid selection doesn't have to be complicated if you carefully check the voltage, bore dimensions, and plug type. Remember to always diagnose the cause of the old one's failure before installing a new component – this will save you time and money.
In the BRhydraulic.eu store, you will find a wide selection of solenoids for the most popular valves and directional control valves on the market. If you have any doubts about which model will fit your machine – please contact us. Our technical department will help you quickly select the appropriate replacement.