Another Reason Not to Disassemble That Servo Motor

Are you thinking about opening up that Rexroth servo motor to see what you can see?

Think twice.

All Rexroth manuals tell you that components can’t be disassembled and repaired on the machine. They always must go to the factory for repair or reman. If you open them up and poke around, you will void your warranty. That should probably be enough to keep you from dismantling that servo.

But sometimes, when the warranty is from so long ago that you don’t think that really matters, the urge to open ‘er up can be strong.

Remember, a reman job gets your component back to you with a new warranty… unless you’ve destroyed the unit so completely that it can’t be serviced. Which happens more than you might think.

Unintended consequences

But let’s get back to that case where the warranty isn’t an issue and your servo isn’t working, so what the heck? What do you have to lose?

Well, here’s something: disassembling a servo motor will almost certainly demagnetize the motor. The magnets, which are essential for functioning, are designed to be permanent magnets.

But the motor is not designed to be disassembled in the field.

So disassembling the motor can discharge the magnets and make your servo useless.

Sometimes you can tell right away that this has happened. In other cases, you might not notice the loss of power until you try to bring the system back into service. It will quickly show an overload error message. Since excessive current can demagnetize a motor, you might assume that the overload caused the demagnetization — not the other way around.

That’s assuming that you realize the motor has been demagnetized. Often, you’ve noticed that the torque seems to be dwindling or maybe your machine is just making a funny noise. By the time you call us, when the servo has failed completely, you don’t remember all the steps along the way.

The big takeaway here: don’t dismantle that servo, or any other part of your drive and control system. Call us first.

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