Need motor advice for large tug.

[Soar Master]

I am building a large single screw tug. It is slightly longer than 4 feet in length. I would like to put a large direct drive low rpm brushed motor in it since I already have a high quality MARINE speed control for it. The only requirement on the motor is that it needs to have a 6mm shaft to fit my Raboesch coupler. I was hoping to find a suitable Pittman or equivelant motor.

I would really like to use a low rpm high torque brushless motor, but I do not know of any MARINE type brushless speed controls with reverse.

[der kapitan]

I am building a large single screw tug. It is slightly longer than 4 feet in length. I would like to put a large direct drive low rpm brushed motor in it since I allready have a high quality MARINE speed control for it. The only requirement on the motor is that it needs to have a 6mm shaft to fit my Raboesch coupler. I was hoping to find a suitable Pittman or equivelant motor.

I would really like to use a low rpm high torque brushless motor, but I do not know of any MARINE type brushless speed controls with reverse.
Loyalhanna Dockyard has some really big Pittmans that you might want to check on.

[patmat2350]

You can get multiple new ends for your coupler to fit most any shaft.

You could also look at this beast from MFA-Como, available via mail order from the UK, or from Harbor Models:
http://www.harbormodels.com/site08/motors.htm top of page.

Has 6mm out; rubber belt lets you avoid gear whine.

Pat M

http://www.harbormodels.com/MFA-Belt-Drive-JPEG.jpg

[toesup]

Try here...
www.goldmine-elec.com

Big 24v Pittman's at $9.95 each :eek:.. USED but complete with 11.5:1 gearhead... which you can throw away at that price!..

If they are sold out, I've had them all!.. :p

[Soar Master]

Toes,

What speed control are you running with the 24 volt motors?

Der Kapitan,

I am checking into the Pittmans at Loyalhanna. Thanks for the tip.

Thank you everyone for your advice. :)

[toesup]

Toes,

What speed control are you running with the 24 volt motors?


They would only be getting 12v... I havnt got the two i ordered yet, i only saw the advert yesterday..
So any speed control handling 12v would be ok..

[Tugboat Andy]

Try here...
www.goldmine-elec.com

Big 24v Pittman's at $9.95 each :eek:.. USED but complete with 11.5:1 gearhead...

Any idea on the rpms at 12 volt? I have a hull that needs some power and $9.95 sounds good.... :D

[pompebled]

Hi Soarmaster,

An ideal motor for this size hull would be a fan motor.
Source: scrapheap.

The motor drives the fan in front of the radiator and usually has left thread (to prevent the fan from working loose).
It has lot's of torque and will turn about any prop with low Amp consumption.

Raboesch has inserts for their couplers to accomodate various diameters.

Regards, Jan.

[Melih PEKOL]

just as you want:

Graupner Speed 900 BB Torque

6mm shaft, high torq, low rpm, 12V

good for single screw large tug

mp

[Soar Master]

I was thinking Speed 900. I e-mailed Hobby Lobby about the speed 900, but have not gotten a response yet. :(

I have a water pump motor that turns 4500 rpm at 12 volts, will push water 20 something feet up a vertical standard size garden hose, but the shaft diameter is 10mm. I can't get a coupler with a 10mm motor shaft to 6mm drive shaft size.

[Ghost 2501]

go to your automobile breakers yard and take a look in the heater systems of some of them, you'll pick up a great motor

[LtDoc]

Soar Master,
Once upon a time I had a too large motor shaft for a coupler. Took the motor and coupler to an automotive machine shop, asked if they could 'turn-down' the motor's shaft. They said they didn't know, but they'd try. Went back later and they had (used a brake grinding thingy, don't ask, I don't know). Can't remember what it cost but was certainly less than a bunch. Took the finished boat by for them to see. Think I can talk them into almost anything now if it's at all possible! Not sure if they were amazed at the 'quality', or disappointed :).
Would I recommend doing it that way? Not really, but if you can't find anything else... why not try?
- 'Doc

[Soar Master]

Lt Doc,

I was thinking about something similiar. I might take the motor apart and see if the machine shop can turn down the end of the motor shaft to 6mm. Better yet would be if Hobby Lobby would return my e-mail inquiry into the speed 900 motors.

[green-boat]

I have a large tug that I'm going to direct drive a 4"- 5 blade prop. The motor that I plan on using is an old industrial 4 brush servo motor. At 6 volts it pulls .75 amps at stall but will rip a wrench out of your hand if it is on the shaft. :eek: So it has plenty of torque and I plan on running it at 24 volts. These motors can be found on fleabay.

[pompebled]

I forgot to mention, these fan motors can be taken apart; as the picture shows, the shaft is milled down to 5mm to accept my Raboesch coupler.

Just like Doc said, the costs are minimal.

Regards, Jan.

[Aerominded]

Better yet would be if Hobby Lobby would return my e-mail inquiry into the speed 900 motors.


Might want to give them a call, SM... with a comany that big, I imagine they can't really keep up with the email traffic... :)

[Soar Master]

I forgot to mention that the water pump motor is a 300 watt motor. :eek:

After more research I am leaning heavily towards the speed 900. It is much smaller and lighter than the BEAST water pump motor and has plenty of power. The speed 900 also happens to have the 6mm shaft that I am looking for. Win/win situation all around. :)

[Greg Hiltz]

I'll toss in my 2 cents worth also. A great source of high torque direct drive 12v motors are from windshield wiper motors. I've used VW ones(bosch), Honda, and Nissan ones. You can use a hacksaw to simply saw off the aluminum casting around the ring gear, leaving the motor case with the worm gear-spiralled shaft. I've had friends simply hold a flat bastard file to the shaft while hooked to a battery and grind it down to the desired size (not deadly precise, but worked OK), if you have access to a metal lathe, spin the front cast case in a chuck and "pretty" it up, then take the armature, spin it in the lathe to machine the worm-spiral down to smooth size, while you're at it, turn it around and polish up the commutator(part where the brushes make contact) with fine emory cloth. I usuall take this opportunity to pull out the magnets from the case, usually held in place by clips, then I can weld mounting tabs parallel each side of the case. Then reassemble, and try it out. Some of these motors, like the older Bosches, had 3 brushes, and were TWO-SPEED motors. Use a ground wire from the case as one lead, and you had a choice of 0- 5400rpm or 0- 3300rpm at the flick of a separate switch. These were great motors, 10 pole, fine wind, ball bearings, and drew 1.6amp at stall! The Honda and Nissan motors were as efficient. The US wiper motors were bulkier and heavier.
Another good choice is a Johnson 970. It is a sweet motor, choice of single shaft-high RPM, or double-end shaft high torque 5000rpm. The prices on these motors are very reasonable, at $25.00 from Lowell Briggs Hobbies.
Ponder this.
-Greg

[Soar Master]

Excellent advice. Thank you. Johnson 970 has the right rpm range. :)

[TugboatTom]

My advice is use a giant automotive fan motor! Those can get pretty darn big! Like one out of a Volkswagen Bug would do. I have one that is like 3" in diameter. Havent used it for anything yet but I will! Oh and the shaft problem, go to www.mcmaster.com. They have industrial U-Joint couplings. If they dont have quite what you need you can always them out to what you need.