3 speed tranny for a tug

[bigford]

i jhave a king hauler 3 speed tranny and was thinking about using it
in something heres the gear ratio and motor
Gear Ratio: 10.6:1 - With the 3-speed gearbox, 10.6:1, 17.7:1 and 32.4:1 are possible
Engine: Electric 540 type motor
whats the thought??? :eek:

[Tug Guy]

My thought is why would you need it? If you gear a large tug down 3:1 it will run all day and give you very good scale speeds. You can go 2:1 or 2.5:1. but why would you want to do more? I am just asking because I don't see the need for more. Maybe I am missing something here and should be jumping on board with this idea?
With all that can go wrong in a boat while running it the tranny going out would be the last thing I needed.

Don




i jhave a king hauler 3 speed tranny and was thinking about using it
in something heres the gear ratio and motor
Gear Ratio: 10.6:1 - With the 3-speed gearbox, 10.6:1, 17.7:1 and 32.4:1 are possible
Engine: Electric 540 type motor
whats the thought??? :eek:

[Boatfox]

i jhave a king hauler 3 speed tranny and was thinking about using it
in something heres the gear ratio and motor
Gear Ratio: 10.6:1 - With the 3-speed gearbox, 10.6:1, 17.7:1 and 32.4:1 are possible
Engine: Electric 540 type motor
whats the thought??? :eek:
Elec 540 turns what 9500RPM?? At those gearing ratios the prop would be turning slow in first gear...almost stopped in second..and third....forget it. This is all relatively speaking of course. Maybe an astroflight on 24vlt turning 25000 would work out great. I'd look for gearing ratios of 1.2:1, 3:1, and 5:1. You figure the prop (2" or 3") spinning somewhere around 2500 rpm for design use. Slower is usable, but that is what an ESC was made for :p
Do a serch on Hectoperm or Decaperm. Those are nice inline (single) geared motors. Little pricey but nice. You want expensive try to find a GT Marx motor.

[der kapitan]

i jhave a king hauler 3 speed tranny and was thinking about using it
in something heres the gear ratio and motor
Gear Ratio: 10.6:1 - With the 3-speed gearbox, 10.6:1, 17.7:1 and 32.4:1 are possible
Engine: Electric 540 type motor
whats the thought??? :eek:

Why bother? With a 540 motor at 3 or 4 to 1, that's about the farthest down you'd want to go, unless you plan on a paddlewheeler. :rolleyes:

[bigford]

i figured i had the 3 speed and shifting gears was fun on road
maybe it would be fun on water. you know drop it to low and pull a house down
kick it up to high and cruse. just a thought

[Kmot]

I think it might work in a speed boat. Once you get moving, start shifting into higher gear. But then, a prop in the water is just a whole lot different than a wheel on a road. As a wheel gets rolling the work is easier. But a prop is just working hard all the time.

[bigford]

kmot you trying to say it's not easy being a prop

[Aerominded]

kmot you trying to say it's not easy being a prop

Hee hee! :D

[keith S]

just going in circles while being all wet. Just can't be "studded" like a tire.

[CG Bob]

The best use for that tranny might be for a towing winch or anchor windlass. Most modern anchor windlasses have two speed electric/electronic transmissions. Most full size vessels with a red (reduction) gear are geared somewhere around 3:1 to 5:1, with the prop turning slower than the motor or engine. Somewhere in my qualification notes for EWO (Engineering Watch Officer) I have the exact gear ratio, it was roughly 3:1. I qualified as EWO on CGC CONFIDENCE (WMEC 619) and CGC VIGOROUS (WMEC 627) back when I served in the USCG.

[TugboatTom]

Yeah why would you need a variable speed trans for a boat? All you need is a one speed gear reduction. Full size boats that are mechanically driven (not diesel electric) just have a one speed forward and reverse. And scale model boats are normally electric powered so you dont even need that. Just a gear reduction. Sorry to say its just simply not practical.

[Shaun Hendricks]

I think this issue is addressed in boats (and aircraft) with variable pitch propellers.

The idea of a tranny isn't to 'shift gears' but to keep the engine in its maximum efficient power band for the application (economy versus performance). Gears are just a way to accomplish this. New car (and truck) transmissions are CVT (Continuous Variable Transmission) and are adapted from ancient tractor technology to do the same thing, only computer controlled. Aircraft and boats do this by changing the pitch of the prop, which has its effciency penalties but when properly utilized can keep the motor in the perfect RPM range for the speed you want. In fact, the engine rarely leaves the RPM range and you go faster or slower by changing pitch, not so much with throttle.

I don't know of a boat 'model' variable pitch prop. Maybe someone else does. It's not a hard thing to design, model aircraft have it right now. Should be doable with a boat.

[Tug Guy]

I seem to remember a varible pitch boat prop made by either Robbe or Graupner some time back. I don't know if they still make it or not.

Don

[LtDoc]

If anyone is making a variable pitch prop it's certainly not very common. Wish it were...
- 'Doc

[patmat2350]

Whys boats don't need no trannies

Primarily because a slow-turning prop just doesn't absorb much torque, so there's no reason to gear down to get more torque there. You want pulling power in a tug, you just take the prop to max rpm's... then it's biting into a lot of water and exerting some thrust.

And on top of that, an electric motor makes max torque at slow speed or stall. This is why a locomotive can get a train moving- it has electric traction motors driving the axles (the diesel just runs a gen-set). No gear shifting needed!

You could always put the tranny in there, but it would just add complification. And I'll wager that it's not even needed in those Tamiya semis... justs gives the operator something to do...

Pat M

[Kmot]

I have on my hard drive, and will locate later when I can do some searching, the variable pitch propeller and drawings that a model boater made from scratch and used on his own model tug.

[Umi_Ryuzuki]

Someone here, kiwimodeler?, has a pair of Raboesch variable(controllable) pitch propellers and something from a company called WADA in Japan.

These are the one's I have in my referance files.

Vario seemed to come up a lot as a "blast from the past" propeller that used to be commercially available.

:o

[Kmot]

I have on my hard drive, and will locate later when I can do some searching, the variable pitch propeller and drawings that a model boater made from scratch and used on his own model tug.
Here it is:

http://steamtug.orcon.net.nz/

[Milesc]

Were can I find or make a gear reduction for my tug, its size is 35”x10” or do I need one. I have a dumas 12 volt motor (1/8” shaft) prop shaft is 3/16” turning a 3” prop.
I looked at SDP Stock Drive Products with no luck seems the two shaft sizes make the pulley selection a no go.

[green-boat]

Instead of gears I would go with XXL belts and pulleys. They run much quieter and require no lubrication. Pulley on the motor and one on the prop shaft, no U-joints needed. If you can't find the right pulley shaft size, you can use a sleeve on the shaft to adapt to the pulley.

[Tug Guy]

If it is a gear reduction you want try harbor models. For belt drive reduction try Sdp or W.M. Berg. Like Green boat says they may need sleeves to fit properly. Sometimes you get lucky.

Don

[Kmot]

Look at the airplane gear reductions. Lots and lots to choose from. Whether you go direct drive, or gear reduction drive, chances are strong the shafts will be different diameters and you need to get the proper sized collar anyway.