A friend Andrew taking his kids for a spin Nov 2006  in my small trike. P3 motor is a rear motor but I've installed
below in some strong front forks from a bmx bike, I had to spread the forks out quite alot but they are very strong.
Motor is designed for rear use.
Motor has plenty of torque to carry all these people, the torque is quite good due to the planetary gear train.
Lucky I built the frame strong is all I can say!



Below a very early design diagram for gear train of the  original motor ( around1989)

Metal gears ( planetary gears) overall reduction ratio approx 7:1

Closeup of metal gears

{Postscript: the best motors being used in solar cars use  axial flux type motors, but they use two sets of magnets on each side of the windings , also they use a halbach array in the magnets and they have many more poles and no gears, they are getting extremely high efficiencies peaking at certain rpm around 98%. The P3 motor and gears peak at just over 70% so the majority of the time the motor will be running somewhere in the 60%-70% range. This does mean this motor will not have as good a range as brushless  motors, but it does have very good torque for hill climbing at low speeds}

One reason I particularly like this motor is the gears are just very robust. The gears that wear down the fastest are the ones in the plastic cage, but it takes a long time for them to wear sufficiently to need replacement. Similarly brushes will need replacing but only after alot of riding, quite a few years. The P5 motor would be the newer equivalent of this motor, the P5 has more torque being brushless and using high torque style motor.

This motor has one continuous axle which goes through the centre of it (previously quite unusual for a geared motor), which means that it can handle quite alot of weight. It was designed for the Chinese ebike market which almost entirely uses Lead type Batteries (sealed lead acid absorbed glass mat type). So its designed to take alot of weight, also the chinese tend to use the ebikes alot for carrying two people or for carrying one person and some goods.

Regenerative braking is not possible with this motor due to it having a freewheel mechanism, though if you spin the motor backwards it will act as a generator (the freewheel mechanism engages if motor is spun backwards). Pic of freewheeling mechanism below: note its all covered in grease usually I've just cleaned all the grease out to make for a clear pic.




Below is the torque graph for this motor for 36volts: ( I've never had a torque graph done for the motor on 48volts)


Graph above is for P3 running on 36volts (if run on 48volts torque will be about the same but top speed increases). 
The graph shows no load rpm is 210rpm. Maximum efficiency is 75%
Maximum power out on 36volts and at 18amps (max. amps of the controller) is about 440watts.


A bit more info on this motor:
The gear systems in these motors are very well made.  All gears are hardened steel and I've done my best to damage it (both on purpose and by accident!) without success. The motor is one of the first motors to be designed in around 1999-2000 by one of the pioneering ebike manufacturers in China ( Luyuan company,now one of the biggest ebike manufacturers in China). There are plenty of the original motors still in use in many parts of china. I have no idea how many of these were produced but most likely tens of thousands of them. They are still produced but only in small numbers as brushless gearless motors have become the most common hub motor type in use in china now(most of the terrain where ebikes are used iin China ( the ( cities ) are quite flat terrain)   During a  visit to China I saw many of these motors still in use. So over the years they have made a few changes in the design ,quite minor changes, but the original design still holds. Some of the changes that have been made are as follows: the freewheel mechanism was changed to all steel initially it had aluminium with hardened steel inserts, they have reduced the number of different rpm motors that come in the motor (from 4 or so down to1), a longer lasting glue for holding the magnets in place and some changes in the resin which holds the windings in place (its an axial flux type motor inside (also called a pancake motor), nowhere near as good as the axial flux motors they use in the solar cars but a similar basic structure.
    This is the first hub motor that I ever bought. I depend on it almost daily, its in my work horse, a trike which I carry shopping, parcels etc in the back. I dont particulary like going too fast and I dont like pedalling much especially up hills, also I like something that is going to be able to take some punishment without damage......perfecto!
 The motors wont last forever though, the gear teeth do eventually wear like any geared motor but having been in use for about 10 years in China already I think it says alot for their quality. There is one particular gear that wears down the most and can be replaced if it shows signs of wear.
    So I learned the ins and outs of this motor myself having taken many apart and put back to together so I know it extremely well. Also my last visit to China in March of 2006 I spent quite alot of time with the guy in the factory who repairs these motors. He has the technique down pat. He can dismantle one of these motors in a few minutes put in new brushes or whatever is needed and have it back together in another 5 to 10 minutes including some basic adjustments (which are needed when puting in new brushes). Most of his repairs to the motor are for replacing brushes but earlier models the glue that holds the neo-dymium magnets in place would loose its grip after some time and also the resin that holds the windings in place would deteriorate over time and crack, the new motors use a better glue and that problem is no longer an issue.
 To maximise the life of the motor I suggest regrease the gears every 2years or sooner if the motor becomes noisy.

Parts in the Kit:

1. Motor
 
2. Cluster 3 or 6 speed:
      

3. Throttle: choice of the ones below: throttles come with matching left hand side

4. Controller: 36volt 20amp or 48volt 20amp

5. torque washers and torque arms:

6. Spokes to suit your rim size: spokes are 2.3mm dia ( thicker than normal bike spokes), mild steel type ( stainless steel are not suitable for use on ebikes as they become brittle and break easily), 36 spokes are required 40 spokes supplied in the kit ( a few spares just in case!)

7. Brake Handles with Cut off Switches: not necesarry to use them, but will cut off controller when brakes are applied if used.