Old School Puma Stripped Right Down

Hello

It was raining and I was bored so decided to strip down an old school 1st generation Puma motor to show you all how it ticks. It is a fairly simple but very effective design, this early one has been improved on a lot, however the principle is still the same.

I dusted down my circlip pliers and crankshaft puller in order to strip the motor down, this motor had been run for a thousand miles or so and there is no wear on the internal cogs at all, also no water or dirt has entered the motor.

The main hub gear is metal as is the main drive cog on the rotor, the only plastic ones being the planetary gears, these can be replaced by simply removing the circlip, although I don't ever see there being a need to, this motor is in good shape and has had a lot of abuse.

Here are some pictures for you, the newer BMX type Pumas are much neater inside and are of a slightly different design, but work around the same principle.

Knoxie

It was raining and I was bored

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Yes, I know that feeling – I'm going stir crazy here. Thinking about using the Etek to drive an outboard...
Thanks for all the great photos Knoxie. It's good to see that there's no wear to the nylon gears as I've been thinking about getting a Puma for my next project but was unsure about their long-term reliability.

Hi Malcolm

Yes the gears were always my worry (this was the reason I stripped it) just to check on things, its perfectly ok, you could put in steel gears if you wanted to? or were worried, they make a great neat compact powerful little motor at a fraction of the price of a heinzmann, not to the same quality of course but good enough!

The weather is so poor although its sunny out there at the moment, need the summer to kick in soon though.

Cheers

Knoxie

Hi knoxie,malc,

is that one of the stamped pumas mate?
looks ok inside - no visible wear, doesn't look to bad to change them if they do wear anyway?

Cheers


D

Hi all
I've got a puma stamped with BMC on the motor is this the motor you have taken to bits?

Hi Geoff, DC

No this isnt the same as the motors you guys have, this motor was a 1 off made for the American market, the rotor on your motors is different, its more or less the same otherwise.

Yes you could change the gears if you needed to, you could even chnage the gear ratio if you had all four gears to swap out, not sure its worth the bother, this motor climbs any hill you point it at and motors at 25mph on the flat, as long as you don't live on a volcanic island it would do most folks.

P

knoxie said:

you could change the gears if you needed to, you could even chnage the gear ratio if you had all four gears to swap out, not sure its worth the bother, this motor climbs any hill you point it at and motors at 25mph on the flat, as long as you don't live on a volcanic island it would do most folks.

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No going Randy on us Knoxie

Thanks for the inside view. Great pics. It does look like it held up well so far. I like the motor design, it should be quite efficient.

Hi Richard

Yes its all in good shape, the newer motors look even better with their clothes off, I will post some pictures as a comparison, they built these a while ago now and have changed a few things. It is a pretty efficient set-up, no magnets to fly off like my Kol motor, although the windings on this motor get a little warmer, need to weave some water pipes in there and make it liquid cooled! ha ha.

I think it has held up quite well, there are a few things I think they could have done better but heck for the money they are pretty darn good, powerful and quiet in operation, you need a bearing puller to split them open but its a 5 min job tops, you can press it all back together quick enough.

They could mill out the rotor this would make it lighter and help air circulation through to the windings and a key on the rotor to drive gear would be a good Idea as well, other than that they are pretty good, now all they need to do is to incorporate 3 speeds internally and it would be perfect!

Knoxie

Hi knoxie

Good use of your time while its wet; very interesting to see the "bare" essentials hope the rains easing where you are and you're not flooded .

I like the look of the puma motors: do you have any torque graphs for any stage of their "evolution", preferably the latest, and do the new ones still weigh only around 8lbs/3.6kg?

What sort of efficiency does it have at speed uphill?

If you kept the amps down, is there any reason you couldn't run 100v on this motor? Say 100v x 20 to 25A?

Nice job, Knoxie!

This is the kind of detailed, pertinent, timely, and useful information I love to find on this site. Your photos just answered a handful of pending questions I had about the construction of the Puma. Looks Good!

-JD

Hi Josh, Lowell

I havent any torque graphs for the motor, its developing around the 100NM mark at 48V I would say, it is certainly a very high torque motor more so than the Currie USPD and a lot more so than most of the 4 and 5 series motors I have tried, the 5 series motors being on a par if you run them at 72V and upwards, the Puma develops amazing torque and high speed even at 37V 35A.

The motor weighs in at 4lbs on its own, which is very light indeed when you consider whats in it and how powerful it is. I have run it at 72V 35A with no problems however it does get a little warm, I dont see a problem running them at 72V 25A or so and the new Pumas will be running at that.

Its pretty efficient, its 6-1 reduction means the motor is running at its optimum RPM mostly, on hills it doesn't bog down too bad at all, I can climb a 16% slope at 12mph no peddling, using Lipo 37V 35A, thats pretty steep, the same bike will do 25mph on the flat, no gearbox required, sure a geared system ala Randys bike would be more efficient but most of the 16% slopes near me are not long enough for that to be a problem.

The Puma is a great option, its cheap, powerful, light, durable and available! which is more that can be said for a lot of motors and kits right now. I still like the 2 speed xlyte and the X5 though, they are fantastic motors and are a proper assist.

Knoxie

oatnet said:

Nice job, Knoxie!

This is the kind of detailed, pertinent, timely, and useful information I love to find on this site. Your photos just answered a handful of pending questions I had about the construction of the Puma. Looks Good!

-JD

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thanks! you are most welcome, I think its fair that I strip all this stuff down for you all to see, I do it with batteries and controllers, nothing is safe when I am around!! ha ha, I like seeing how stuff works, I can make it work better then!!

Cheers

Knoxie

where does one buy a Puma hub motor ??

Dr K, Very nice pictorial!

1) What speed do you predict for Puma, 72v, 35a, 26"

2) When you refer to the Puma's torque and hill climbing prowess what size wheel are you using?

Thanks,
A

Hi

To answer the other poster, the Puma motor or BMC stamped motor can be got from evtech in the states and thesuperkids, in the UK from Team Hybrid.

Speed at 72V 35A was about 45mph, however it is a little too much power for this motor to run reliably I feel, a more sensible 25A at 72V will give great speed and torque and a safer margin on reliability for the motor and controller.

Cheers

Knoxie

Hi all
knoxie can you tell me what size axel the bmc stamped motor uses, thread that is it looks like an M12 but I have no M12 bolts handy to try the nuts with.

Hi

They are 1/2 inch from memory, dont put 12mm bolts on there you will ruin the threads, you may find even with 1/2 inch bolts the threads are a little tight, some of them just are, don't over tighten it though just tighten it as you would a normal wheel and fit the torque arm if you have one.

Cheers

P

knoxie said:

Hi

They are 1/2 inch from memory, dont put 12mm bolts on there you will ruin the threads, you may find even with 1/2 inch bolts the threads are a little tight, some of them just are, don't over tighten it though just tighten it as you would a normal wheel and fit the torque arm if you have one.

Cheers

P

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Hi All
Thanks Knoxie, I think that you meen don't use m12 nuts on the axel but I know what you meen.
Checed out the types of nuts avalible there are UNC and UNF the one wanted are UNF which is a 20 tpi mesured off the axel.