7mm Poor man's Alamosa.

[Big Train James]

Ochre turtleneck's need to be the adopted dress cope for all MoM's going forward......

Nope.

 

[Scale7JB]

So, I’ve been working every day since I get back from the US trip, so today treated myself to a strip down of the biggun to see if I could get it running.

Alas, as expected a no go, though not for the reasons I expected. Usually with these older loco’s it’s solid grease in the gearboxes. On this occasion it’s due to perished rubber gromits that hold the motor in place.





This causes the motor to short out on the live frames of the engine. No major problem as it could really do with a new modern DCC friendly motor anyway.

Has anyone any recommendations? I had a Quick Look on MSC and they have the JH motor which looks big enough and suitable. JH motor only — MSC Models I won’t need a gearbox as I’ll use the existing 2 stage gearbox which looks pretty good to be fair. I just don’t think the usual Mashima will be strong enough for the job on this occasion, even if I have removed the solid cast weight in the boiler.

I did also treat it to some chemical black on its tyres. Huge improvement in appearance already.



JB.

 

[PhilH]

JB,
In the past I've used Crailcrest and Pittman motors to replace open frame motors in US locos.
This Pittman motor on Ebay may possibly be of use:

MODEL TRAIN ODDS - PITTMAN 8414F723 - 12VDC GEARED MOTOR - 11/6/91 - LOT 15 | eBay

Its fairly old and may be well used, but possibly worth considering. I don't think its geared as the reference numbers on Pittman gearhead motors usually begin with the prefix "GM". The size would be approximately 30mm dia. x 60mm long without the flywheel.
I've used a Pittman motor on my D&RGW C48 and its OK on DCC.

 

[Scale7JB]

JB,
In the past I've used Crailcrest and Pittman motors to replace open frame motors in US locos.
This Pittman motor on Ebay may possibly be of use:

MODEL TRAIN ODDS - PITTMAN 8414F723 - 12VDC GEARED MOTOR - 11/6/91 - LOT 15 | eBay

Its fairly old and may be well used, but possibly worth considering. I don't think its geared as the reference numbers on Pittman gearhead motors usually begin with the prefix "GM". The size would be approximately 30mm dia. x 60mm long without the flywheel.
I've used a Pittman motor on my D&RGW C48 and its OK on DCC.

Thanks Phil,

If Pittman is the possible way forwards, I'll have a rummage through all the american bits. I'm sure theres a Pittman in there somewhere from the American diesels.

Question is, are they metric or imperial mounting screws??!

JB.

 

[Big Train James]

I have a bunch of Pittman gear motors if you have any interest in that setup. These are the good motors with the rare earth magnets and ball bearings. I can dig one out tomorrow if you are interested.

Jim

 

[Stephen]

The Sunset Brass Mk-5 that I have is fitted with a Pittman motor, and in all honesty it runs pretty well. I’ve only ever ran it using a an H&M Safety Minor, but it’s pretty smooth, despite some dodgy connections between the loco and tender. Hopefully it should be able to be DCC’d in the future.

Although your brute is twice the size of the Mk-5, I would have thought a Pittman motor of sorts would be suitable for the job, and I’m pretty sure some of the other Sunset articulated locos I’ve looked over had Pittman motors too.

Cheers,

Stephen

 

[Scale7JB]

Thanks chaps, that could well be the way forward then.

I’m not sure quite how big the motor needs to be as it will never pull a long train, and I’m tempted to take the drive off of the front bogie, to preserve the daylight under the boiler.

Who know’s, it’s all fun.

JB.

 

[Big Train James]

I've got a bunch like this. Don't pay any attention to the gear ratio, as it can be changed without too much effort. There's a big stack of compound gears inside the housing, it's easy enough to pull what you don't need, or I can substitute a 19.5:1 stack from another motor. These are now essentially excess to my needs as I've changed my approach to drive design, and the gear motors are no longer applicable. This particular version also features a 12mm shaft on the opposite end from the gear head, which is ideal if you want to use a flywheel.

 

[Big Train James]

Here are several data sheets for the common Pittman motors. The 6000 series are almost certainly too small. The 9000's are big but are generally too slow for our purposes. The 8000's are just about right, which is why they have made their way into gazillions of O scale locos over the years.

 

[Big Train James]

It would appear from the data sheets that the mounting holes are 2-56 threads on the motor and 4-40 threads on the gear head. You might check with Right-O-Way as Jay used to use the Pittman 8000 gear motors all the time. He has a motor mount listed on his website that says it's for Pittman 8000 and 9000 series motors. I am however a bit confused because the hole pattern for the screws doesn't seem appropriate for the claimed application. It still might be worth contacting him.

One thing to remember with the gear motors, you don't necessarily need further reduction as it can all happen at the motor. For a long time Jay would use a 1:1 helical gearbox with 8000 series gear motors with a 19.5:1 reduction for his drives. He seems to have switched to Faulhabers in the past several years, but the concept still applies. Anyway, you might not be able to simply "plug" this into the existing gearbox(es) and get the speed you want.

Jim