Lockridge Device - Peter Lindemann

[Mark]

Mark
I am getting 3900 rpms (Dead even too) out of the motor, at 72 volt, .5 amp.
and recovers about 36 volt .5 amp (+ or -) per rotation. The higher voltages in the cap are contributed to any spikes produced in the recovery half of the motor.

The stock one runs at 2600 rpms, at 24 volt just under 1 amp.

Thats all free wheeling though. You see things change when you add a mechanical load.

Matt

Not bad Matt. I tried to run my modified motor today at 72 volts and let a little bit of the smoke out . It happened almost immediately so I wont be doing that again.

The recovery numbers above, are those with the brushes in the stock location, the "generated recovery"? Or have you moved the brushes and that is from the back spike.

My stock motor runs 3355 rpm's at 900ma so either mine is a little different or your maybe a little tired.

Mark

[pault]

Pault

My 12 volt motors must be a little different than yours. Both ends of mine have bushings, no bearings. And I think I can glue my cut boards on top of the other ones and wont have any clearance issues.

My bad use of words. Yes, I've got bushings. The brush end is held down by a black spring metal disk and swivels if you insert the axle and pull - probably a production trick to allow wider tolerance of fit.

My commutators taller than a brush, but the extra is "lost" below the 2nd board when I push the armature all the way in with only one spacer.

pt

[Matthew Jones]

Mark
I am getting 3900 rpms (Dead even too) out of the motor, at 72 volt, .5 amp.
and recovers about 36 volt .5 amp (+ or -) per rotation. The higher voltages in the cap are contributed to any spikes produced in the recovery half of the motor.

The stock one runs at 2600 rpms, at 24 volt just under 1 amp.

Thats all free wheeling though. You see things change when you add a mechanical load.

Matt

[Peter Lindemann]

Saving Money

Ok, tried with a glove and I could easily bury a 5 amp meter with the stock motor and could only get 2 amps out of the modified one. My bad.

Mark,

I'm with Matt. I LOVE the cheap "lab test".

Peter

[Matthew Jones]

Ok, tried with a glove and I could easily bury a 5 amp meter with the stock motor and could only get 2 amps out of the modified one. My bad.

LOL

[Mark]

Ok, tried with a glove and I could easily bury a 5 amp meter with the stock motor and could only get 2 amps out of the modified one. My bad.

[Matthew Jones]

Use a glove Mark, you can hold on longer.

I am not running 48 volt anymore I am running 72 volt.

I am not sure of the speeds I'll throw a little flywheel on it and Tach it later this afternoon. Let ya know.

Matt

[Mark]

Pault

My 12 volt motors must be a little different than yours. Both ends of mine have bushings, no bearings. And I think I can glue my cut boards on top of the other ones and wont have any clearence issues.

[Mark]

Matt

I'm wondering if the stock motor your testing might have something wrong with it, is it one from the junk yard or is it a new one?

[pault]

2nd set of brushes

I see two ways of mounting the 2nd set of brushes on the 12VDC (P.A.) motor and I've started (but haven't finished) fooling with both.

0) I think I want the motor to turn CW (looking down, brushes at bottom). This seems to give the the most real-estate for the outrigger springs.

1) Snip the 2nd brush board (tin snips work) and drill relief holes to cozy the board into position and glue it to the main board. It seems that this will require adding another spacer or two on the brush end of the armature to "lift" it up enough to compensate for the added height of the glued-on board. This will mean that the case will not close all the way. I don't see this as a problem. In fact, it might be an idea to add "spacers" cut from the 2nd board scraps between the casing the and the brush end when reassembling.

2) Remove the brush casings and pins from the 2nd board and attach them to the main board, drilling new holes. It looks like it *might* be good enough to attach only the front end of the brush casings to the board and simply let the rear end hang over the edge of the board attached to nothing. The spring pins are "riveted" into the board - I'm not sure how to re-attach them to the main board (force fit into a smaller hole, and crazy glue?).

I'm favouring 1, and will fall back onto 2 when I found out if there's a gotcha ...

Odd point - the bearing on the brush end is not fixed, its a round ball held down by spring metal. You can tilt the axle / bearing assembly. Need to check that it is not tilted off-axis when reassembling.

pt

[Mark]

Also one more thing to add.
I tested (Not a good enough test though)a stock motor that is 24 volt 15.4 amp motor with the one I have rewound.

When I grab the shaft of the stock motor I can slow it down with my hand and make it draw about 12 amp at 24 volt.
The same pressure applied to my 72 volt model only draws a little over an amp.

So equal amount of work. 288 watts in the stock. 72 in the modified minus recovery.

Its not real good test and I am going to move to a pony break as soon as I can get my hands on the parts I need. But its nice to see this can work.

I can't wait to hook it up on my motorized Skateboard.

Matt

I am getting totally different results than you Matt. My new stock 24 volt motor draws 900ma @ 24 volts and when I grab on to it I can only get the amps up to 2.25 before it burns my fingers in about 3 seconds. With my modified motor running at 48 volts I can only get it up to about 700ma. So both motors draw about twice as much. What kind of speed are you getting out of your modified motor at 48 volts?

[Matthew Jones]

While were on it any good recommendations for pony break system. I have been looking them over but I would like to review some more if possible.

Any helps appreciated.

Matt

[Peter Lindemann]

Looking Good

Also one more thing to add.
I tested (Not a good enough test though)a stock motor that is 24 volt 15.4 amp motor with the one I have rewound.

When I grab the shaft of the stock motor I can slow it down with my hand and make it draw about 12 amp at 24 volt.
The same pressure applied to my 72 volt model only draws a little over an amp.

So equal amount of work. 288 watts in the stock. 72 in the modified minus recovery.

Its not real good test and I am going to move to a pony break as soon as I can get my hands on the parts I need. But its nice to see this can work.

I can't wait to hook it up on my motorized Skateboard.

Matt

Matt,

This is a very encouraging report. Your Prony Brake idea is the right one. If you can quantify the mechanical power gain, you have all but proved the thesis.

If you remember, I show how to build a dynamometer (Prony Brake) in Electric Motor Secrets, Part One.

Keep up the great work.

Peter

[Peter Lindemann]

Too Early to Compare

Thanks for the heads up Peter. I wish I had a scope and knew how to use one.

One thing I'm concerned about is that when comparing the modified to the stock motor I'm not seeing any significant advantage like I expected. Matt's setup without collecting the spike and collecting the generated output appears to be better. Your reflection on this would be appreciated. I'm wondering if a 6 brush set up would be better on the 4 pole motors. I haven't started working on the 2 pole motor yet so maybe things will be different with that one. Don't know a lot to learn still.

Mark

Mark,

No need for concern. You are still just "idling" your test set-up in the "high back EMF" zone, so performance ISN'T better. If fact, it is probably worse because you are building current limitation into the motor's operation.

Motors will ALWAYS rise to the speed where the back EMF reduces current input. When we are done with your mods, the motor may be capable of 12,000 rpm UNLOADED, but we will LOAD it to about 3000 rpm to "stay ahead" of the back EMF. Again, the goal is a GAIN in mechanical power, based on being able to apply high torque pulses at higher speeds than usual.

In the normal run mode, the motor has this seemingly "wonderful" self-regulating feature where the motor automatically draws more current when a load is applied. Your modifications are removing this operating feature. After your modifications, the only way to make the motor rise into the load is to raise the voltage. You can see this starting to happen with Matt's unit.

Don't lose sight of where we are going with this. Eventually, we want to run the motor on capacitor discharges, and the capacitors will be able to charge to higher and higher voltages the faster the system goes.

Hang in there!!!! You are on the right path.

Peter

[Matthew Jones]

Also one more thing to add.
I tested (Not a good enough test though)a stock motor that is 24 volt 15.4 amp motor with the one I have rewound.

When I grab the shaft of the stock motor I can slow it down with my hand and make it draw about 12 amp at 24 volt.
The same pressure applied to my 72 volt model only draws a little over an amp.

So equal amount of work. 288 watts in the stock. 72 in the modified minus recovery.

Its not real good test and I am going to move to a pony break as soon as I can get my hands on the parts I need. But its nice to see this can work.

I can't wait to hook it up on my motorized Skateboard.

Matt