Shop fan - slow to start

[Chaznsc]

A good friend gave me an old 2-blade shop fan. In the video below, notice how the electric motor moans to life. At about 15 seconds in in full spin,even tho the video doesn't show that.

Is the electric motor dying and is there something I can do to revive it?

Thank you for reading.

-chaz

 

[gasserdan]

I would at least blow some compressed air in the motor. It sure would not hurt it.

 

[engineer2]

Yes, compressed air to blow the **** out of it and try lubing the bushings or bearings. If that doesn't do it, it might be an elctrical issue (bad cap, brushes, bad winding, etc.), depending on what type of motor it is.

 

[Mark in Indiana]

I'm going to take a wild guess at this:

First: Does the motor spin easily without power? If not, the bearing(s) are bad.

Second: Check the centrifugal switch in the back of the motor.
Basically there is a START speed winding and a RUN speed winding in the motor. A centrifugal switch in the motor should first power the START winding, then at a certain RPM, powers the RUN winding.

I'm guessing that there is something not right with the centrifugal switch, and you're powering the RUN winding at start-up. The noise is the excess load on the RUN winding. Much like starting to move a car in 4th gear, rather than in 1st gear.

If you can post a picture of the motor data plate, that may help.

Good luck.

 

[6PTsocket]

Yes, compressed air to blow and **** out of it and try lubing the bushings or bearings. If that doesn't do it, it might be an elctrical issue (bad cap, brushes, bad winding, etc.), depending on what type of motor it is.

+1

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[LS6 Tommy]

I'm going to take a wild guess at this:

First: Does the motor spin easily without power? If not, the bearing(s) are bad.

Second: Check the centrifugal switch in the back of the motor.
Basically there is a START speed winding and a RUN speed winding in the motor. A centrifugal switch in the motor should first power the START winding, then at a certain RPM, powers the RUN winding.

I'm guessing that there is something not right with the centrifugal switch, and you're powering the RUN winding at start-up. The noise is the excess load on the RUN winding. Much like starting to move a car in 4th gear, rather than in 1st gear.

If you can post a picture of the motor data plate, that may help.

Good luck.

^^ This^^.

Tommy

 

[tjdux]

I would be suprised that size of fan has a start and a run but it's old enough looking to maybe have such a thing.

I collect fans on the curbside all the time that are thrown away because they start slowly. 9times out of 10 same problem is the bronze bearings need some lube. A quick squirt of wd40 and power them up and they work fine. Granted this is mostly big box store chineese fans that are much newer and plasticy looking than yours, but still worth a shot. Also some proper grease is needed for long term fix as wd40 will dry out somewhat quickly.

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[American Locomotive]

A lot of older fans have motors with low starting torque. I'd check the bearings to make sure they're lubed and spin freely. I wouldn't worry about it unless the motor gets scorching hot while running.

I have a 1930s fan that takes a solid 10-15 seconds to get up to speed.

 

[HOTFR8]

Would some WD-40 help ?

 

[6PTsocket]

Would some WD-40 help ?

Not the lube if choice. Try 3 in 1 electric motor oil, the blue container. If it has bushings, it should have felt packings to hold oil and external holes to put the oil in. WD is really designed to dry out wet electical parts. WD stands for water displacement. After the solvents evaporate it leaves a little very thin oil behind. It is a rather poor lubricant. It is not the greatest rust buster either.

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[HOTFR8]

Not the lube if choice. Try 3 in 1 electric motor oil, the blue container. If it has bushings, it should have felt packings to hold oil and external holes to put the oil in. WD is really designed to dry out wet electical parts. WD stands for water displacement. After the solvents evaporate it leaves a little very thin oil behind. It is a rather poor lubricant. It is not the greatest rust buster either.

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Thanks for that. What about if the fan has dust in it? Would the oil still resolve the issue?

 

[btdobie]

That is, by my best guess, a split phase motor. No capacitors just a primary and starting coil. The starting coil is disengaged by a centrifugal switch when it gets up to speed. The primary is always on. Most likely scenario is centrifugal switch isn't closing.

 

[tjdux]

Not the lube if choice. Try 3 in 1 electric motor oil, the blue container. If it has bushings, it should have felt packings to hold oil and external holes to put the oil in. WD is really designed to dry out wet electical parts. WD stands for water displacement. After the solvents evaporate it leaves a little very thin oil behind. It is a rather poor lubricant. It is not the greatest rust buster either.

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I agree with wd40 being a poor lube but its common. I really need to get aomebof that 3in1 electrical oil. Many of the cheap fans i picked up curbside definitely dont have oil holes in the exterior but they are easy enough to take apart.

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[glentre]

If the above suggestions don't work, check out the configuration of the motor. Some older ones had the stator turning around a fixed shaft with the fan attached to the stator field instead of the rotor. These motors take a long time to come up to speed and that is normal for that configuration.

Glen

 

[6PTsocket]

If the above suggestions don't work, check out the configuration of the motor. Some older ones had the stator turning around a fixed shaft with the fan attached to the stator field instead of the rotor. These motors take a long time to come up to speed and that is normal for that configuration.

Glen

That is interesting and new to me.. Reminds me of the WWI rotary aircraft engines. The whole engine with prop attached, spun. The crankshaft was bolted to the firewall.

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[Bert_]

Most fan motors do not have a centrifugal switch. The motors are usually either shaded pole of permanent split capacitor types. Both of these types of motors have low starting torque and do take some time to come up to speed when they have a heavy blade attached. If your fan takes excessively long to come up to speed or you can feel some drag when spun by hand then I would either simply lube the bearing with the appropriate oil or disassemble and clean the motor and bearings then lube them.