Johnson 2R72M

[david-bartlett]

quote BillW:

I’m not really clear with the pictures….is there, or is there not, a conventional drive shaft and pinion gear? I’m not so much caring how it drives anything right now…I am just wondering if they are THERE? (If not, what was the point of having a gas motor connected to nothing?)

Let’s suppose I was a Johnson engineer with big dreams and time on his hands. What I might try to make would be a hybrid outboard…When the conventional gas power head ran, it would drive the prop and the electric motor, which might function as a generator to charge a battery. Then, fishing, the electric motor would be able to drive the prop shaft directly with some kind of clutch that would maybe centrifugally disengage from the gear.

Hey, what do I know? Why not? Maybe the engineer went on to Toyota and made the Prius.

PS…I can’t believe this is your first Johnson? What are you going to do for an encore, when you get a second one? A Wankle? Gas turbine?

Bill,

It appears to me that there is no pinion gear in there. I can see what looks like the hole the drive shaft comes through. Curiouser and curiouser all the time.

[fleetwin]

Is there, or isn’t there a pinion gear?

[slim60]

The pinion (not pictured) fell out when I pulled the L/U and removed the drive gear. The prop didn’t spin because of the different shaft for the electric motor.

[wiscoboater]

Can you get a picture from the bottom of the electric motor looking up? Would love to see how that all ties together down there.

[fleetwin]

OK, so there is a pinion, so ignore my previous comment. Looks like the gear is linked to the prop shaft with that pin. So, I’m guessing there is some sort of one way clutch/spring in that gear that allows the electric motor (when used) to spin the prop shaft freely (without turning the gear).
Try spinning the inner part of the gear, will it spin freely in one direction?

[slim60]

I put it together today connecting the yellow wire to the brush assembly and the springs in the brushes. Then connected the leads to a deep cell and pushed the switch…nothing. I ran the engine and connected a test light to the leads and pushed the switch…nothing. So in review the engine turns the motor and shaft. Prop would turn too but the shear pin is missing.

[slim60]

Here is a photo of the switch.

[fleetwin]

OK, so the prop does spin when you run the gas engine. Not quite sure just what/where you were testing with the test light though. Kinda sounds like you are not getting power through the switch? Try connecting the ground lead to the battery then just tapping the positive lead to the battery with the electric motor switch turned on. Any sparks?
If my hair brained theory is correct, try spinning the prop shaft with vice grips (and the spark plug lead off). Can you spin the prop shaft freely in one direction? I’m thinking that gear has some sort of one way bearing/bushing that allows the electric motor to spin the prop without spinning the gears.

[slim60]

The drive gear shear pin would not come out, it’s too long and I didn’t want to break it. So I could not remove the motor. That’s all for now. I’m going to Spread Eagle to play with my KG-7. I’ll try to bring the 2R72M to Tomahawk. Thanks for your help and interest. Slim

[slim60]

I had to cut my vacation short due to business at home so I won’t be at Tomahawk with the Johnson hybrid. I would be willing to send it up with a member who is passing through S.E. Wisconsin. I’m two minutes from I-94. Just thought you guys might want to take it apart and see how it ticks. 262-857-2465. Btw, the KG-7 was a blast. I think I got close to 25mph!

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