October 23, 200916 yr I am looking for a new motor for my self contained hammer. There is a 3 h.p., 1720 rpm currently on the machine. What do I look for in a quality replacement. Will there be any problems going larger?
October 23, 200916 yr I think the main thing is to get it to run the same speed What is the problem with the motor you have 3 ph and you need single or is it burned out. You certainly dont want to go smaller, slightly larger may be better as I am not sure if the one you had was under sized or not. The larger the motor the more amps which cost more electric and the motor probably will cost more up front also.
October 23, 200916 yr Look for a motor rated for continuous duty and with windings not open to the air as shop air tends to be hard on motors. TEFC, Totally Enclosed, Fan-Cooled, would be nice.
October 23, 200916 yr Author What is the problem with the motor you have 3 ph and you need single or is it burned out It's pretty much burned out. Well, I shouldn't say that because I don't know too much about motors. I can coax it along by spinning by hand but it's getting worse quickly. Having a hard time finding someone to take a look in my area. Any ideas?
October 23, 200916 yr How are the brushes? Can you get at them to check? It might a quick and easy (inexpensive) fix. Bill
October 23, 200916 yr I'm interested in knowing how to check if a capacitor is on the fritz. The motor on my bandsaw did a stragne thing the otherday. First it started slow but ran:confused: then it started slow then quit:mad:. I can hear the brushes rubbing when I trun it by hand...
October 23, 200916 yr Tom has a very good point. TEFC motors are resistant to metal and abrasive dusts getting into them. If you have to spend money on a new motor, and don't have a used inexpensive motor that you can use, the investment in a TEFC motor will likely last you longer. Baldor makes nice TEFC motors. Look for a motor rated for continuous duty and with windings not open to the air as shop air tends to be hard on motors. TEFC, Totally Enclosed, Fan-Cooled, would be nice.
October 24, 200916 yr You may match up the motor frame # so that you get the same shafting and motor mounts. Or have the motor rebuilt which by rule of thumb is 75% of a new one.
October 24, 200916 yr Universal (brushed) AC motors commonly run WAY to fast for a power hammer. You more than likely have a AC Induction motor, and they do not have brushes. Sounds to me like the capacitor is gone. They are an easy fix. The capacitor is used to get the motor STARTED, and from that point on it will run at a steady speed. If the capicitor is gone, the motor will not start. Instead it will just sit there and hum. The fact that you can COAX it into starting leads me to believe it is the cap.
October 24, 200916 yr Author Sounds to me like the capacitor is gone. They are an easy fix. The capacitor is used to get the motor STARTED, and from that point on it will run at a steady speed. If the capicitor is gone, the motor will not start. Instead it will just sit there and hum. The fact that you can COAX it into starting leads me to believe it is the cap. That sound about right. The capacitors are likely in one of the the round bump outs on the top of the motor, correct? I'm pretty green when it comes to this stuff. How do I go about testing/fixing the problem. I started messing with it some more and took off the fan guard and had a peek. There is a spring loaded mechanism next to the fan and when I joggle that and spin the shaft at that location, VOILA.
October 25, 200916 yr The capacitors are likely in one of the the round bump outs on the top of the motor, correct? There is a spring loaded mechanism next to the fan and when I joggle that and spin the shaft at that location, VOILA. If you have 2 "BUMPS", and a spring loaded mechanism, then you prolly have a split phase motor. The spring loaded mechanism is a centrifical switch that energizes the start up windings, in conjuction with the caps. Once up to speed, the switch opens and the motor runs normally.
October 28, 200916 yr Author I'm interested in knowing how to check if a capacitor is on the fritz. The motor on my bandsaw did a stragne thing the otherday. First it started slow but ran then it started slow then quit. I can hear the brushes rubbing when I trun it by hand... I googled "fixing capacitor on motor" and the first hit had some good info on testing. I haven't taken mine off to check it yet...have to coax a few more jobs out of the hammer.
October 29, 200916 yr Author Problem solved!! I wish sometimes I was one of those guys who loves to take stuff apart and see what is goin' on in there. Mostly I just want stuff to work so I can squish the metal, but from now on I'm going to confront these mechanical problems head on! Probably. Took off the fan assembly to have a look at the "centrifugal switch" today and whats this?... theres a set screw missing and the switch is spinning freely on the shaft. And whats this?...theres the little screw on the floor. Five more minutes and problem solved.
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