reverse switch wiring ?

hi all
my ml7 came with a dewhurst and partner reverse switch ,but onl
ran in fowards . ive followed the diagram in the manual and put th
extra two wires in for reverse ,but the lathe wont run at all ! iv
double checked the wiring now and its as drawing :confused: , iv
removed the bridging links , the motor is a "brook" the terminals ar
marked a1 , a2, z1 and z2 and im asuming the "z" terminals are th
start windings ! can anyone enlighten me as to the fault ??
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willowkevi
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willowkevin
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Sorry I can't help,but there is actually a forum on Myfords site,someon
there might be able to tell you.
Alla
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Allan Waterfall
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Are you still confused?
I am! I can't see why two extra wires are needed for reverse operation.
Al four motro connections are needed for forwards or reverse operation. I assume you are using the diagram in the Myford handbook? if not this states:
switch connection number Motor terminal 2 Z1 start 5 A2 run 6 Z2 start 7 A1 run
1&2 single phase Mains input
If you have wired it like this and have no luck, then more analysis is needed.
Wire the motor direct with mains line to A1 and Z1 and mains neutral to A2 and Z2.
Note motor direction.
Re wire with mains line to A1 and Z2 and mains neutral to A2 and Z1.
If the motor runs in the opposite direction then the motor is fine and the fault lies with the switch or wiring.
With no power applied to the switch, open it up and by observation see how the winding changeover switching is meant to work and check through with a continuity tester/ohmmeter/battery and torch bulb/whatever is handy to see where the fault is.
Hopefully this will sort you out
If not come back - with some more info- and I'll try harder!!
Good luck
Bob
Reply to
Bob Minchin
sorry :o bad explanation ! the 2 extra wires iput in were from th
switch to the motor as it was wired on /off thru the switch with th motor windings bridged accross a1\z1 and a2/z2 . the motor is a "broo gryphon
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OK I understand that bit now.
So are you still stuck or has the suggested analysis sorted out the problem now?
Bob
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Bob Minchin
hi
well, when i bridge a1\z1 and a2\z2 and wire live to one pair an neutral to the other pair, and switch on the motor runs foward ,problem is, it still runs foward when i reverse the wires
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Just to be absolutely sure. You are changing the bridging from a1/z1 and a2/z2 to a1/z2 and a2/z1 when you do this test not just exchanging line and neutral?
If so then it might be that the starter winding or starter capacitor are open circuit or perhaps the centrifugal switch inside the motor has failed. Although normally this means that the motor will not start at all, sometimes they will start in one direction by themselves when the run winding is powered up. To test this theory, with the power off, spin the motor in the opposite direction to normal and before it stops switch on the power. If any of the starting components are faulty, then the motor will continue to run in the direction that you manually started it in. If it starts running the otherway, then the starting components have influenced the start and so are likely to be OK
Regards
Bob
Reply to
Bob Minchin
Hello
You only need to swop one of windings to obtain reverse direction running, therefore a1/z1 and a2/z2 becomes a1/z2 and a2/z1.
Hope this helps Ian
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Ian Cockshull
whoops, no ive only swapped the wires ie neutral to a1\z1, neutral t
the other pair and then ive swapped them so live is to a1\z1 ! (whic is how it was before i started !) so tonight i'll swap the bridge link and post back ! i'm very puzzled about this now ! but its years sinc ive worked on a motor ....the other puzzle is there was a piece of core cable about an inch long left behind in the switch gland nut
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