Lockridge Device - Peter Lindemann

[Hiwater]

lockridge device

I was looking for a Flywheel today for the scooter motor and found an old ceiling fan motor hub. The center hole on the fan motor is just a hair too small, so would have to de drilled..The bearing would have to be spot welded to the shaft on one side. About six inches in diameter and two inches wide. This little unit is just heavy enough to work for these scooter motors, wont know for sure untill I try it out to see how it works. Might be worth a try. Hiwater.

[n84dafun]

Grinding wheel flywheel

Here's what I'm talking about. It's a little different from what I described earlier. This one uses coupling nuts and a threaded rod down the center.

Another idea is to simply use the rotor of a spare motor for a flywheel.

Brian

[n84dafun]

Grinding wheels for a flywheel

Mark,

For a flywheel, you can use grinding wheels stacked together. Here's a link to some grinding wheels that might fit our motor.

Grinding Wheel

They are well balanced and can spin up to 13k RPM. The 3/8 arbor size is slightly smaller than the shaft, which is 10mm, so you can drill it to fit the shaft. I was thinking of getting a metal tube with an inner diameter of the shaft and getting grinding wheels with an arbor size same as the outer diameter of the tube. Then simply slip the wheels onto the tube, which would be longer than the width of the stack of wheels so that you can put a set screw on both ends of the tube for both motor shafts. You would have to epoxy or weld the wheels on the tube.

Brian

[Matthew Jones]

Hello Matt

Did you ever get a flywheel made? I found something that works good but needs to be balanced. The top of a old GM air filter housing. The hole in the center is the perfect size and when I ran it on an unmodified motor it had good speed and coasted good after removing the power and connecting the leads to a 12 volt 1 amp light bulb. It does vibrate quite a bit but the weight and size work real well for these little 24 volt motors. Its 15.5 inches in diameter.

Mark

Ya my guy is working on it. He's busy since he the only one around for 90 miles. Basically just had him run 3/4" shaft through 4 1/4" plates of steel. Then he's going to drill a 7/16" hole in each end and mount set screw to bolt onto the flat spot just behind the thread.
I've haven't heard from him though so its not finished.

Probably next week. The Lower Slower South, ya know??

Cheers
Matt

[woopy]

At all

i remember of this fantastic time of my electric RC car races and i forgot to say.

When a small brushed DC motor is intended to work at very high current , it needs a "perfectly brushes /collector adaptation" And if the motor is brand new, the brushes are not perfectly adapted to the collector ( so sparks will happen through the tiny gap between brush and collector)
So a "run in" time is really helfull
So i suggest that you let the motor run some time ( perhaps 1 hour) , at low voltage and current ,before you proceed to the modification.

Just 2 cents

good luck at all

Laurent

[woopy]

Hi Pault

the better way , i know, to renew the collector after spark errosion is to put the rotor in a lathe and carefully lathe the collector. So you get a perfectly flat and brand new collector. You can do it 2 our 3 time as the collector copper is thick enough. But as i sayd "CAREFULLY"

It is what i did when i was involved in electrical RC car races, where the brushed motor had to support very high amperage and get rapidly black and damaged.

Hope this helps

Laurent

[Mark]

Hello Matt

Did you ever get a flywheel made? I found something that works good but needs to be balanced. The top of a old GM air filter housing. The hole in the center is the perfect size and when I ran it on an unmodified motor it had good speed and coasted good after removing the power and connecting the leads to a 12 volt 1 amp light bulb. It does vibrate quite a bit but the weight and size work real well for these little 24 volt motors. Its 15.5 inches in diameter.

Mark

[Matthew Jones]

I just sand them with 400 grit. You can use emory cloth as well.

Matt

[pault]

It wasn't a good idea to use a dead SLAB for the recovery battery. The motor wouldn't start today. I took it apart. The brushes look OK, but the two copper commutator sections are completely blackened (and probably non-conductive).

Is there a recommended way to clean them? I'm thinking of trying Brasso, and/or emery cloth.

The one good thing about this design is that I still have 8 perfectly good unused commutator sections - I can always rewind one slot over

pt

[FRC]

Flywheel

Do you have a flywheel in between the motors ? I was wondering what results you would get with one in place, and pulsing the run motor.

I am not sure, but shouldn't your output be going to a load or cap at least ?

FRC

[pault]

Back-to-back test jig

I now have a back-to-back test jig - the modified 12V motor driving an unmodified motor of the same kind as a generator.

I'm running the unmodified motor unloaded and simply attaching an analogue voltmeter to its leads.

I'd appreciate any advice about the setup and the desired measurements.

I did a few quick test runs:

voltage in, current in, generated V in un-mod'ed motor, RPM
12.54V, 5.6A, 11v, 3333RPM
In a minute or so, the current dropped to 5A, then 4.7A

25.33V, 6A - had to stop to tighten a bolt

25.17V, 7.25A, 16V, 6,000 RPM
23.58V, 5.7A, 14V, 4,285 RPM (after 90 sec of running)
23.42V, 5.7A, ??, 3,750 RPM (after 4 minues of running).

I tried to swap a dead SLAB in on the 2nd pair of brushes and ran the back-to-back at 37.3V, but I saw sparks inside the motor, and stopped.

Advice would be appreciated.

If this looks like a dead end, I can wind another armature differently, since I've got a spare armature.

pt

[Matthew Jones]

Dragon is right. Makes it real easy to determine the horsepower or watt output.

Matt

[dragon]

If you have a 1 ft arm and are measuring in lbs you simply multiply those together. The formula becomes...

ftlbs x rpm / 5252 = HP x 746 = watts
________
Electronic Cigarette

[Eric]

Ya use a 1 foot piece of wood and 1 scale. Makes it real easy to calculate. Tighten it down till you get a certain RPM, then you can do your calculations.
Maybe use a scale that measures in fractions of a pound and up to multiple pounds.


Matt

how do we alter the math in calculating for the 1 foot arm to the scale are we adding it to the circumference of the wheel?

[theremart]

RE: Prony break.

ok so i decided to set and learn how to run a prony brake test running my motor in stock mode to get some output numbers to compare with for when i modify the winding.

below is a picture of the setup and a table of results, the first time i tried to run a prony test awhile ago i used delron plastic to make a wheel of known circumference when i tried the test the plastic got too hot and melted to the leather strap didnt know it untill i hit the power again the wheel didnt let go of the strap and it ripped my 50 Newton spring scale apart. ooops. so i moved on to other things.. this time i used 28lb scales used to weigh fish and a piece of thick aluminum tubing and epoxied a piece of delron in the core and trimmed this down to a 6inch circuference bored and tapped the center to use the threads on the shaft. it spins really nice, no flex if i reef on it up and down with my hand, you have to spin the moter very slowly to see there is a very slight wobble in the wheel. after running a few brake tests the wobble hasnt grown. unfortunately i reached 28amps on the last test so i needed a bigger gauge. the 0 to 100 gauge i have appears to be giving me readings that dont match up with my smaller gauge so i will have to find anouther gauge.

i am wondering is there a point where useing this leather strap method might be unwise (ie will leather stretching yeald bad results) should i switch to a different setup like shown here de Prony brake - Wikipedia, the free encyclopedia useing a wooden arm to pull on a spring scale?

Hi,

I also was thinking thru how can one figure out how accurate the prony brake was.. I believe the way to do is is to take a motor of known horse power and use that to calibrate the setup. As you mention there are many variables that need to be worked out and it looks like you are making good progress in your method.

But picking up an electric motor with X horse power that is in range of your measuring scales may be the way to go to get a ballpark idea if your measuring technique is accurate.

Just a thought.