This is topic strange motor..... in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Josh Jones (Member # 447) on 01-30-2001, 09:41 PM:
A friend of mine stumbled across this in a pile of junk. It is a century motor, 1/8th HP, 1750 RPM. I pulled it apart to examine it and found brushes, but no wires connecting to them. This leads me to believe it is a early induction motor, but what was it used for? any ideas?Josh
Posted by Paul G. Thompson (Member # 655) on 01-30-2001, 11:24 PM:
Josh, it probably more than likely an induction motor. Were there any electrical connections to the slip rings? If so, it may be a circuit completion for the start winding. I saw a motor similar to what you described 48 years ago in an old drill press at high school. And, it was a Century motor.(not the projector kind) There was another motor I saw that had brushes that appeared to be connected to nothing other than motor case ground, and the armature had a communtator. It, too, was a 1/8 hp motor. I was fooling around with it and discovered I could change the motor speed by moving the entire brush holder plate. I think it had something to do with rotating magnetic field "timing". It was an induction motor. 
Seems to me that opposite communtator segments are "connected" through the brushes and brush holders to give the "repulsion" magnetic field, to, shall we say, shove the armature or (repel the motor field)??? Just a thought. maybe some old motor guys back in 1902 can tell us better. 
Posted by Josh Jones (Member # 447) on 01-31-2001, 04:06 PM:
Well, I was fooling around with that motor this afternoon. It turns out the armature has some flyweights on it. The brushes are only used durring the starting cycle. When the armature reaches a certain speed, the brushes are lifted from the commutator, The transformer action in the windings ceases and induction takes over. Very cool to watch. Also, When the brush plate is rotated, the direction, not speed, changes.Josh
Posted by Josh Jones (Member # 447) on 01-31-2001, 04:13 PM:
Also, The Century logo on this motor looks identical to the one on projection equipmentJosh
Posted by Scott Norwood (Member # 30) on 01-31-2001, 04:17 PM:
What kind of motors are normally used with Century projectors? I've seen Westinghouse and GE (?) motors on the R3 soundheads. I've never heard of "Century" motors, but that certainly doesn't mean that they don't exist.
Posted by Paul G. Thompson (Member # 655) on 01-31-2001, 06:28 PM:
Scott, there was a "Century" motor. Although I could be wrong, I didn't think it had anything to do with Century projector manufacturer. However, when our motors go south on our Centurys or Cineshitties, we replace them with Grainger's Dayton brand. I have seen one on a REAL old drill press, was kind of a goofy looking motor. The one I had is similar to what Josh is mentioning. Maybe you know, but the logo on those motors looked very similar to some old Century motor-generator sets.
Posted by Jon Miller (Member # 163) on 01-31-2001, 07:35 PM:
Josh,Sounds like what you have is a "repulsion-induction" motor. The "repulsion" part (the brushes and commutator) made for higher starting torque, especially under low-voltage conditions, than a regular induction-start motor. A quick bit of research shows this type of motor was used in projection equipment at one point, as shown here.
Century, the motor manufacturer, was never related to the Century projector folks. BTW, there are Century-motored Century projectors out there: I know of one facility in my area using circa-1974 DA projector heads with R3 soundheads, apparently factory-equipped with Century motors. Curious, isn't it?
Posted by Paul G. Thompson (Member # 655) on 01-31-2001, 07:42 PM:
Hey, Jon! Thanks alot for the web reference. That has to be the one Josh was talking about and one of the ones I was hinting about. I bookmarked that page for future reference. Again, thank you.
Posted by Josh Jones (Member # 447) on 01-31-2001, 09:45 PM:
Yes that sounds like it. I'll try and get a picture tomorrow...Josh
Posted by Gordon McLeod (Member # 33) on 02-01-2001, 08:36 AM:
Most of the older century's up here used hoover motors on them then later westinghouse and then GE and then the imfamous bodines
Posted by Barry Floyd (Member # 385) on 02-01-2001, 11:57 AM:
I've got two "Century" motors that were used to turn Motigraph Model 7 soundheads. I've never taken them apart, but they both run great. Strange though, when you turn them off, as they begin to slow down, they'll make a "click" then a slight "buzz" then eventually stop turning. It sounds as if there is a "clutch" of some type disengaging.
They've got some really heavy fly-wheels mounted on the front
------------------
Barry Floyd
Floyd Entertainment Group
Nashville, Tennessee
(Drive-In Theatre - Start-Up)
Posted by Paul G. Thompson (Member # 655) on 02-01-2001, 05:32 PM:
Barry, the following should discribe the noises you hear. I got this from a RCA website that Jon steered me to.31. Single-Phase Repulsion-Induction Motor.- A repulsion-induction motor is used as a projector drive motor on PG-10 equipment. One of these motors is illustrated in Figure 19. The rotor of this machine contains a commutator and is similar to the armature of a DC motor. The stator is wound with a four-pole single-phase winding. This winding is somewhat similar to the field winding of a four-pole DC motor. The starting device consists of two brushes mounted so as to make contact with the commutator, a resistor to prevent the motor from coming up to speed too rapidly, and a centrifugal mechanism for shorting out the entire commutator after the motor has attained sufficient speed to run as a single-phase induction motor. As stated in section 30 the action of a single-phase induction motor, when its rotor is stationary, has the tendency to turn the rotor in both directions at once. This action, of course, results in no rotation at all, but, if by some means this balance can be disturbed, rotation will result. The brushes short-circuit a part of the commutator so as to unbalance the torque set up by the rotor current. The current in the rotor is due to the transformer action between the stator and the rotor. The unbalancing action caused by the short-circuited portion of the rotor gives a predominance of torque in one direction so that the motor starts to rotate. The direction of rotation depends upon the position in which the brushes are mounted. The running winding will keep the motor running in either direction once it is up to speed. If the brushes were short-circuited through a very low resistance, such as a copper wire, the starting torque would be too great and an excessive strain would be put on the projector mechanism. A resistor of 9 ohms resistance is used to connect the two brushes together through the frame of the motor itself. This reduces the starting torque sufficiently to prevent undue strain on the projector.
Posted by Bruce McGee (Member # 131) on 02-02-2001, 08:28 PM:
Century motors were used in oil furnaces on the burners, and also on the belt-driven blowers I have several of them out in my garage.All of mine have a big C on the bearing cap opposite the shaft end.
I dont think they are being built anymore.
Posted by Aaron Sisemore (Member # 145) on 02-02-2001, 10:28 PM:
>>I dont think they [Century Motors
] are being built anymore.<<Yes they are. They are a division of AOSmith
http://www.aosmithmotors.com
Aaron
Posted by Bruce McGee (Member # 131) on 02-03-2001, 07:13 AM:
Aaron: Thanks for the link.I saw the Centurion line at their site.
The oil furnaces that used nothing but Century motors was the HALLMARK furnace company. If you have a Hallmark in the basement, go and see if the motors are Century's. They probably are. Very dependable as long as they get oiled now and then.
AO Smith took over the Westinghouse motor lines a few years ago. I hope that they did not change any of the designs. Westinghouses were built like tanks too.
Boy, is this EVER a diverse site!!
Posted by Paul G. Thompson (Member # 655) on 02-03-2001, 12:14 PM:
Bruce - those Westinghouse motors - they are definately built like cast iron out houses. There are several Westinghouse motors that drive some of our old ferries here in Washington State. They were built around 1926, and still run like new. WSF fianlly had to get one armature and field re-wound. Not a bad record 74 years in service...
Posted by Paul G. Thompson (Member # 655) on 02-03-2001, 09:24 PM:
Josh - I just sent you a picture of a drive motor presently in service in one of our ferries up here in Washington State. If anyone else would like this picture, please email me. This motor is HUGE!
Posted by Matthew Bailey (Member # 601) on 02-05-2001, 11:29 AM:
I have seen two Simplex installs one time.
One was powered by a Kirby vacuum motor,
another an outdoor install without any
walls was was ingeniously powered by a
small Briggs&Stratton engine.
Posted by System Notices (Member # 2357) on 11-19-2006, 11:02 PM:
It has been 2113 days since the last post.
Posted by Scott Norwood (Member # 30) on 11-19-2006, 11:02 PM:
Bump.
I seem to have encountered one of these "Century" motors. It runs fine with no load, but the "full speed" mode never seems to engage when it is under any load at all. The projector (a JJ) turns over easily and runs fine with another motor (a Westinghouse). This particular motor has been idle for at least eight years and I ran it for a good half-hour before trying to drive the projector with it. There is a big sticker on it stating that it uses sealed bearings that do not need oil.
I don't know much about motors. Is this something that a standard motor shop could fix and/or rebuild, or would it be better to just get a new motor? Is there a generic replacement motor that would work, or do we need to order something from Strong? If I remember correctly, this is a 1725-RPM model. Do the JJs use the same motors as the MSA models?
Posted by Ron Curran (Member # 3631) on 11-20-2006, 12:54 AM:
Yes Scott, I was told by a motor manufacturer that oilable motors presented the problem of contaminants entering the oiling points, which is why his were designed as sealed.
I have not checked the validity of that concept over service life.
Posted by Louis Bornwasser (Member # 3063) on 11-20-2006, 01:38 PM:
Scott..by all means, let the motor shop repair it. The old ones fit well and start slowly. Usually the start switch is bad. Solid state replacements for the start switch work well. Louis
[ 11-20-2006, 03:30 PM: Message edited by: Louis Bornwasser ]
Posted by Gordon McLeod (Member # 33) on 11-20-2006, 09:00 PM:
Be aware that some solid state motor start switchs will have issues with some slow start kits