Alternator rotation direction?
Discussion
The answer, is of course, a resounding "it depends"....... ;-)
If there is a one way clutch built into the drive pulley (modern alternators use this to relief torsonal vibration loads on the FEAD system during things like WOT at low rpm, gear shifts or even ABS brake events etc) then obviously this will not allow a torque direction reversal.
Assuming it is an old Alternator and has no one way clutched pulley, then you should be able to spin it backwards, howeverm note a couple of things:
1) the cooling fans built into the rotor will not be quite as efficient as the blade angle will be wrong. However, these fans are rated for full output in 50degC heat, so unlikely to be an issue in a kit car (assuming it hasn't got much Electrickery installed!)
2) if it is a s/h alternator, the field energisation brushes will have worn somewhat lopsidedly, running it backwards may initally result in a slightly funny noise as the bushes wear the otherway
So in general, it shouldn't be a problem to run it backwards as the individual winding (phase) output AC power signals are passively rectified and so don't care about phase order!
If there is a one way clutch built into the drive pulley (modern alternators use this to relief torsonal vibration loads on the FEAD system during things like WOT at low rpm, gear shifts or even ABS brake events etc) then obviously this will not allow a torque direction reversal.
Assuming it is an old Alternator and has no one way clutched pulley, then you should be able to spin it backwards, howeverm note a couple of things:
1) the cooling fans built into the rotor will not be quite as efficient as the blade angle will be wrong. However, these fans are rated for full output in 50degC heat, so unlikely to be an issue in a kit car (assuming it hasn't got much Electrickery installed!)
2) if it is a s/h alternator, the field energisation brushes will have worn somewhat lopsidedly, running it backwards may initally result in a slightly funny noise as the bushes wear the otherway
So in general, it shouldn't be a problem to run it backwards as the individual winding (phase) output AC power signals are passively rectified and so don't care about phase order!
Thanks MaxT
Further info...It is a new aftermarket 40amp unit so no issues with clutches or existing wear patterns.
The builder had installed the alt. further back due to lack of space and fitted it with a jack shaft running in a pillow block bearing just behind the pulley. The whole arrangement would have been almost impossible to keep aligned. Net result was a broken mounting at the bearing and a destroyed alt.
Time to design a new mounting.
Thanks again.
Steve
Further info...It is a new aftermarket 40amp unit so no issues with clutches or existing wear patterns.
The builder had installed the alt. further back due to lack of space and fitted it with a jack shaft running in a pillow block bearing just behind the pulley. The whole arrangement would have been almost impossible to keep aligned. Net result was a broken mounting at the bearing and a destroyed alt.
Time to design a new mounting.
Thanks again.
Steve
Steve_D said:
Thanks MaxT
Further info...It is a new aftermarket 40amp unit so no issues with clutches or existing wear patterns.
The builder had installed the alt. further back due to lack of space and fitted it with a jack shaft running in a pillow block bearing just behind the pulley. The whole arrangement would have been almost impossible to keep aligned. Net result was a broken mounting at the bearing and a destroyed alt.
Time to design a new mounting.
Thanks again.
Steve
Rather than redesign the entire thing, could you install a coupling that allows a some degree of misalignment? e.g. like thisFurther info...It is a new aftermarket 40amp unit so no issues with clutches or existing wear patterns.
The builder had installed the alt. further back due to lack of space and fitted it with a jack shaft running in a pillow block bearing just behind the pulley. The whole arrangement would have been almost impossible to keep aligned. Net result was a broken mounting at the bearing and a destroyed alt.
Time to design a new mounting.
Thanks again.
Steve
Mr2Mike said:
Rather than redesign the entire thing, could you install a coupling that allows a some degree of misalignment? e.g. like this
Yes that type of coupling is a possibility and keep the jack shaft arrangement but the rest of the mounting is so badly made I'm more inclined to thow it all in the scrap and start again. We will see.Steve
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff