Linear Solenoids 101: Push vs Pull Solenoids vs Push-Pull Solenoids

Every linear solenoid is essentially a pull solenoid – but a pull solenoid can become a pushing device through the incorporation of a pushrod. The picture below illustrates the construction of both push and of pull solenoids, showing both open frame and tubular solenoid design.

When a linear solenoid coil is energised, magnetic flux flows between the moving plunger and the fixed polepiece. These are drawn together regardless of the polarity of energising current. This is the basis of linear solenoid design, which is a pull solenoid.

The push type solenoid takes the pull solenoid and incorporates a pushrod attached to the plunger, which passes through the polepiece. This is the mechanical difference providing a mechanical ‘push’ force at the other end of the solenoid.

The Push-Pull Solenoid

This is a specific type of linear solenoid (other types include open frame, tubular, latching, and proportional) designed to provide very high force at a low stroke. The picture to the right illustrates the construction of a ‘push-Pull’ solenoid.

This solenoid incorporates mechanical means to attach a load to either the armature (pull) end, or the base (push) end of the device.

When energised, the moving armature is attracted towards the fixed polepiece of the solenoid (like the pull solenoid described above). It is pulled in the same direction regardless of the polarity of excitation.

The shape of the case and polepiece of the push-pull solenoid are optimised to develop very high holding force in the fully energised (closed) position.

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