Bad Overland drives, total write-offs?

[De Bruin]

Sorry if this has been done previously. I was going to reply to Sarge's and JS's posts regarding GP-30's but thought more folks might want to continue ruminating on Peter's most excellent CF7 or the aesthetics of hoods units in general which is a topic I certainly enjoy.
I agree with Sarge that the styling of the GP-30 stands apart from both its predecessors and successors. Add Overland to the brass builder list; they did a multi-version run of GP-30's including the PRR's with the induction antenna's.
Unfortunately they had the tube to -"domino" tower P.O.S. drive.
So opinions about the aforementioned OM weak tea drives? Can they be made operable or are they just replacement junk?
Ditto the truck frame, which appears to sometimes "take a bend" laterally after continuous running with a load.
Looking at replacing or fixing at least four of these, so any opinion by the brain trust is appreciated.
Pete

[bob turner]

CLW.

These things were designed for a test run, then the mantel/ display case.

[sarge]

My slightly different take;

The first thing to determine is whether the older version or newer. The older one is pretty much crap what with weird gear ratios, early E units the example. If the tower ratio is 1/1 or, like the E units, a ratio increase rather than the expected ratio reduction, marvel at the lunacy if that bit of patchwork and get tearing.

The newer ones though, once adjusted properly, give decent performance. The C628 I showed in "Paint Shop" has that drive and I've elected to keep it, at least until I blow it up.

Then, remotor it. The weeny motor is the biggest flaw in the stock setup; absolutely unworkable for any sort of use beyond the testrun into the display case.

Now you can think of "Purpose". An extreme environment, like the one Bob holds all drives up to, will kill these pretty quickly. For anything less than Bob's 24hrs a day at the museum with no periodic lubing, they can give decent service; I'm thinking home layout or the club modular display for an hour or two, and making sure the gears stay properly moist with lube (oil, not grease).

That said, I call them "needful" but not crystal fragile, rather like an Italian car. If the above points you to keeping the drive, then a good sorting of the flexible bits, lining up gears properly, and importantly a replacement of the anaemic little motor with something a bit more "V8"-ish and they will handle home-layout level use quite satisfactorily.

Importantly, these drives might not play well with others. Mixed consists might prove daunting to create what with weird performance. My C628 (oddly, to me) runs well with an Atlas China-drive U23b once the latter makes the infamous "Leap of Starting". This is an important consideration, and where I would probably be quick to replace just for standardisation.

I have seen the later drives with proper gear-ratios, once sorted and with decent motors, do very well long-term pulling respectable trains such as later E's pulling an old Mort Mann era Broadway Limited up 2.5% curved gradients, but each train would run an hour an operating session and they were well-cared for.

Otherwise, if changing drives becomes the proper choice, my standard is CLW and Weaver chain drives sprocketed down a bit. I have good luck, and this should be considered the budget method. Jay C. has his drives which are more engineering-correct than mine, beautiful running and longevity reputations and appropriately a bit saltier than my approach.

Its your call, but my recommendation for "normal" usage, if the later drive, just get rid of the tiny motor for a good one (no option there;the weakest link by far) and go through it, lube it up with oil rather than grease and give it a go. Then make the call whether tearing out and re-driving is warranted.

Regarding spreading trucks, that one is a new one on me. Has someone ballasted them up? The quick solution is a new truck bolster properly gusseted for stiffness.

[Jay Criswell]

Because I'm lazy and, basically, a mal-functioning illiterate, I'll make it brief.

Early drives = total junk, a throw away

Intermediate = better. This classification really covers a large span. How about, later intermediate drives can be made to run well.

Later (including current production) = much better. Still don't like the miniature gears used in the truck towers.

Formed brass truck bolsters could be a problem if abused. Later versions are cast white metal.

Jay

[bob turner]

I guess I agree. I have heard that later drives got a lot better.

I have been using LaBelle Teflon grease on worm gear assemblies with good outcomes.

[De Bruin]

Thank you gentleman; I was unaware about the marginal improvement in the gear tower over the years, nor the issue regarding early, odd gear ratio.
Agree the factory Sagami cans were were wholly inadequate and will replace. In this context I'm intrigued now to disassemble and inspect these to see just what's there, at there very least I'll be installing u-joints and shafts to replace the tubes.

[Jay Criswell]

Pete,

Yes, smaller Sagamis, used in HO, were great motors but the 32mm was absolute crap. It was replaced by a cheap Pittman (third digit is a one) that was only a marginal improvement. The latter versions used Pittmans with better magnets.

[De Bruin]

Thanks Jay, good to know. I believe mine have the budget Pittmans but I'll know for sure when the hoods come off.
Addressing Sarge's question re the truck side-frames bending, my experience with that is specific to an OMI E-unit; both truck frame sets bent after maybe 20 hours(two motors later) of running, the unit was not weighted and typically was hauling 6 or 7 cars.
My theory is continuous running in one direction on the DFW club's former oval modular layout and my own smaller oval back then, as in running left hand curves continuously. That's my theory at least, that and apparently soft brass castings of the frames themselves.
Pete

[cole7015]

OK

Here is what I do to my OMI diesel models. I throw away all the junk motors and use a Pittman 40x60 9000 series
from NWSL . I have 3 OMI Baldwin Centipedes with 2 motors in each one. Each model weighs 6 lbs 8 oz. they will pull the wall down.

The copper wire was replaced with cable ties around the motor.

Bill Basden

[Jay Criswell]

Formed brass bolster. Not very strong but bending under normal use is news to me but if Pete says it happened to him, I believe it.


Oh yeah this is what sits above the offending bolsters.


Jay

[R.K. Maroon]

Jay, I noticed that your gear tower comes up in the middle of the truck, where the kingpin might be expected. Is the kingpin offset (often the case on three-axle trucks) or do you have some clever design here?

I am also wondering if I am the only one whose eyebrows went up when Bill said he owned THREE centipedes.

Jim

[Jay Criswell]

Jim,

Ideally, you want the u-joint (or whatever) centered over the kingpin (screw in this case) but sometimes you just can't do it. Here are some closeups of this scenario with the model.





As a coincidence, I just received an OMI DD40X from a friend. It has the stamped brass truck bolsters and it appears they have spread just enough for a few of the axles to fall out of their journals. I was taking some photos but the battery in my camera died so it's being recharged. I took apart one truck and the bolster looks fine. I really believe the biggest problem with these models is shipping them with all the pressure applied to the trucks. The factory box actually has a cutout for the rather large fuel tank. If they had placed a piece of foam under the fuel tank and let is take the majority of the weight, and shock created during rough handling during shipment, none of this would have happened. I'm willing to bet most of the bent truck bolsters were damaged in this way. I doubt very few modelers check this before running their models.

Once the battery is recharged I will attempt to take, and share, more photos.

Jay

[Jay Criswell]

Another issue is the drive shafts themselves. Besides wanting your u-joints, ball & sockets, etc. directly over the kingpin it is highly desirable to keep your drive shaft as perpendicular as possible. The more severe the angle the more wear on the u-joint. This is especially true when using the NWSL dog-bone and socket. It is important to lubricate them. I prefer white lithium grease.

Jay

[Jay Criswell]

Double "D" back together.

Absolutely all the weight on the wheels and zero support of the fuel tank. I submit, this is another case of damage during shipping. Not really the sellers fault. I consider it poor packaging from OMI. Any shock is transmitted directly to the wheels and then to the axles and their journals. Besides poor design of the factory packaging the formed brass bolsters become the next weak link. They flex and the axles pop out of the journals.

When I ship this model back you can be sure the fuel tank will take the majority of the support.

Fairly heavy formed bolster.
Twin cheaper Pittman motors
Factory box and packing actually showing a cutout for the fuel tank
Assembled model

Jay

[up148]

Formed brass bolster. Not very strong but bending under normal use is news to me but if Pete says it happened to him, I believe it.


Oh yeah this is what sits above the offending bolsters.


Jay

Jay, what is this model? Almost looks like a "B" for the OMI turbine. The only issues I've ever had with formed brass bolsters bending (slightly) is on brass trucks that don't have the end stabilizer bars joining the RH and LH side frames. Most OMI models came with these attached, although on early model they can become lost or removed for some reason by previous owners.

BH