# Reversing Motor



## TheSGC (Nov 15, 2007)

How easy is it to reverse an ADC K99-4007? (Same this as the K91, but has a different shaft) I have a Honda, and the engine turns clockwise if you are facing it from the passenger's side, and is counter-clockwise if you are on the driver's side looking at the AC compressor. I am about to order one of these up, but I just want to know if the process is simple enough, or if I need to send it out. It is a reversible motor, so it shouldn't be too hard I think....


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## Mr. Sharkey (Jul 26, 2007)

If you are going to order the motor, order it to run counter-clockwise. There is an optimization of armature timing that is completed according to motor rotation. If you order it CW, then reverse it CCW, your efficiency will drop dramatically, and brush wear will increase, as well as risk of plasma damage to the commutator.


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## TheSGC (Nov 15, 2007)

I would, but the problem I am getting this from a surplus store, so any order-specific requests don't work. I am getting this for dirt cheap, so I don't really mind having to redo it myself or send it back out for adjustment.


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## Mr. Sharkey (Jul 26, 2007)

Not being familiar with the specific motor mentioned, reversal of a series field motor is usually accomplished by reversing either the field coil polarity, or the armature polarity, but not both. This requires that both the field and armature have external connections on the motor (or are available for changing inside the motor), and are connected for direction with jumpers. Simply reversing the polarity of the DC current that runs the motor will not cause it to turn in the opposite direction if the field and armature aren't rewired.

Just be sure to check out the rotation timing. It's usually done with an adjustable ring that hold the brushes. Turning the ring changes the timing of the brushes on the commutator. Other than that, I have no clue what you use as an indicator as to how far to change the timing...


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## Hi Torque Electric (Dec 23, 2007)

I thought this thread might be a good place to start my postings here. If the motor has 4) terminals then you just have to switch the 2 "A" terminals with each other or stich the two "F" terminals with each other to reverse the rotation as was posted. If this motor has just 2) terminals (AKA, pump motor) then the jumper between the armature leads and the field coils is internally connected. It can be modified by seperating that connection and adding two additional terminals.

As for brush advancement, motors usually come set with a neutral brush timing, although some pump motors can come with a small preset advancement (like 4.5 degrees) for the direction it was intended to run in. Some motors do come with pre-set advancement holes and you want your commutator (CE) end plate to be rotated opposite the motors intended rotation. In general if installing your own advancement holes using 10 degrees is a general rule of thumb. I do have a picture on my site showing a how to tell if my motors advancemed here:

http://hitorqueelectric.com/gallery/v/Step_by_step/Brush+Advancement/ 

Hope this helps.
Cya
Jim Husted
Hi-Torque Electric


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