Electric motor Horsepower advice for Steeplcab loco

[Glenn Brooks]

Hello all,

I see I didn't phase my question well at all! I hope some one can assist me in determining how big an electric motor to install in this old Steeplecab switcher...

I Would like to rehab this old 12" ga Steeplecab electric loco, built in 1965 by another hobbyist. The loco is a ride in model, about 7' long and 28" wide in body, and presently weighing around 300- 500 pounds, as is. It no longer has its electric (or maybe original gas/diesel) motor, but is still equipped with an old model T transmission and chain driven drive system, and also a 'Motormans' electric switch throttle - rather cool!

Here it currently sits, awaiting return to life:

I would like to use it as a switcher to help me lay track for my ROW and then pull four or five lightly loaded passenger cars, so a total possible draw bar weight of maybe between 10,000 and 12,000 pounds.

Ian really not knowledgable about electric power systems. Can anyone advise me what the possible horsepower rating might be (of a 24v electric motor) that I would need to repower the loco?

Thanks for any and all advice!

Glenn P.

[duckman903]

I'm finding it very hard to see where you get 5 or 6 ton of weight, but back to your ? I'm thinking that you probably want something like golf cart motor, then gearit for 7 or 8 MPH. JMHO take it for what it's worth.

[rrnut-2]

Take a look at one of these. Also on this site are the bigger motors.

http://www.electricmotorsport.com/ev-pa ... hed-motors

A little pricey, but they do work and with the gearbox already in there, you will have the gear reduction
that will make it work.

Jim B

[Glenn Brooks]

Thanks Duckman and RRnut,

Yep, 5 tons might be a bit much for draw bar weight, although 12' ga equipment can be pretty large. I have two rolling stock with the Ottaway- a 5 passenger car and a drop flat car. Both are 12' long. I figure additional passenger cars might hold 5 adults @ 220# each = 1600 pounds+500 for the car itself. So conceivably, each car could weigh 1 ton. More or less. Certainly a ballast car of say 8'x2' x2' could be loaded with up to 3000# of crushed rock.

As a point of curiosity, does anyone know of a rule of thumb for figuring horsepower needs for a model loco with an electric power source??? Also I guess I need to get up to speed with gear ratio's, wheel diameter, and engine speed -also how much weight is needed in the loco for traction. All very interesting stuff.

Gpb

[larry_g]

http://www.republiclocomotive.com/ac_tr ... ction.html

http://www.republiclocomotive.com/tract ... tions.html

Above is the real world calculations. I would expect that they could hold near true for scale locos also.

[Glenn Brooks]

http://www.republiclocomotive.com/ac_tr ... ction.html

http://www.republiclocomotive.com/tract ... tions.html

Above is the real world calculations. I would expect that they could hold near true for scale locos also.

Hi Larry, thanks very much for,these links. Very informative. I need to read through the two links again - Maybe several times to understand how to apply the formulas to my steeplecab. One issue is I am limited to about 50' to max 60' radius turns. So having some trouble getting my head around higher degree of curvature than discussed for mainline prototype operations. Also, haven't yet settled on overall tonnage or train weight. So these are still a bit unknown factors.

But I think these links will really help me decide how to recondition the loco.

Many thanks
Glenn

[Oilcan]

Larry:
Thank you for the links to the Republic Loco site. They have some great information!

Neil

[Pontiacguy1]

Does this thing weigh 500 lbs with you in it or just by itself? I'm going to assume that the weight given is for the locomotive by itself, and that you are going to be riding in it and that you weigh 200 lbs. If that is the case, then your entire locomotive will weigh approximately 700 to 750 lbs, fairly equally divided onto each of the 4 axles.

If that is the final weight, then your locomotive will weigh about the same as a lot of the weighted-down 1 1/2" scale electric locomotives such as an F unit or GP. A lot of those locomotives run a 500 watt motor on each axle, geared down to give them a top speed of somewhere around 8 MPH. They have plenty of power and can slip the wheels. A friend of mine builds these things in his spare time, and he has a 4 axle locomotive that weighs about 500 to 600 lbs, and he used 350 watt motors on each axle, and geared them so that the top speed was about 8 1/2 MPH. He says it has plenty of power, can run all day long, and will slip the wheels rather than stall or overheat, even on 2 1/2% grades or more.

If you have really tight curves, you might want to consider mounting your motors directly onto the wheel/axle assemblies like the prototype did. This would allow you to negotiate very sharp turns without worrying about binding. With the weights given, you might want to use a 500 or 600 watt motor on each axle, geared appropriately. Of course, if you want your top speed to be more than about 8 MPH, you might have to gear it higher and use a slightly more powerful motor.

My point is this: Your locomotive isn't going to pull nearly as much tonnage as you earlier stated, simply based on the available weight for adhesion, no matter what the gauge is. Putting a 4 or 5 HP motor in there would be overkill because you'd just be slipping your wheels and not pulling any more weight. 500 watts is about .6 HP, so with four 500 watt motors, you'd have about 2 1/2 HP at the rail head. That's all that a 700 lb locomotive is going to be able to put to the track anyway. If you are planning on adding a bunch of weight to it, then up the wattage accordingly.

[cbrew]

this loco is the largest and heaviest electric loco i have built to date,
it weights in at 902 lbs.
I have a 500 watt motor per axles, it does have plenty of power to spin the wheels.

BUT. on long pulls the motors having run very warm to hot to the touch. now i have yet to find out what is too hot.
did i read this right, this is a 12" gauge loco?
if so i would look at using 1000 watt 48 volt motors.
you can not have too much reserve power

[Glenn Brooks]

Hi Cbrew and Pontiac guy, thanks for your input. Great info. As general background, Yes, the loco is 12" gauge. Hard to estimate on weight - it is fairly light compared to the Ottaway, so am guessing 350-500 pounds as is- without rider or batteries or motor - basically just a shell with two trucks at present. Top speed would be 7 -8 MPH. Curves are either 50' or 60' radius on my short back yard track- which I am grading and getting ready to lay this spring. Iam hoping to finalize grade under 1% grade. My biggest concern is that 12" ga equipment is heavier and more volumetric generally than 7.5" ga, so payload weight can creep up fast. so would like this Steeplecab to work well as a yard switcher and work engine on a future, more robust railway. Iam beginning to think about increasing the loco's overall weight and tractive effort. Also whether it is worth the extra cost.

May I ask, in your experience, with the 7.5" electrified loco's mentioned above, what draw bar/pulling capacity do they have? E.g. How much weight can they reasonably pull, given current setup?

Thanks much,
Glenn