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Hi Guys

 

I've been HO scale for more years than I care to admit, and now I'm having a go at O.

 

So this is my first topic - as much to see how to drive the forum as anything else.

 

Toe in the water time - I bought an Atlas SDP-35 and a Weaver GP-38.

 

I'm not sure how to drive the photo gallery, but here goes . . .

 

 

 

Anyway, I've tarted up the Weaver with hoses, bell, cut levers and windshield wipers.  All good.

 

The loco ran poorly at low speed, so I put an idler on the chain to stop it from lashing.  Beautiful!

 

 

 

Except for a loud, moaning sound coming from the Pittman motor.  The only way to stop it was to turn off the BEMF in the Loksound decoder.

 

Not an ideal situation.

 

So, my question is, are all Pittman motors like this - or did I just get a dud?

 

If they are all poor quality, what should I change it with?

 

I've uploaded the photos but I can't insert them into the spaces in the text.

 

Not bad for a first attempt. 

 

Cheers

 

 

OL 01

OL 02

 

 

 

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  • OL 02
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Those Pittman Cans are super motors in my opinion.    Similar models of Pittmans used to be in many computer printers.   They would last for ever and even then you can salvage the motor when the printer wears out.

 

It might be something about the signal from that decoder, or even maybe it is set in "switching" mode and sending a modified DC signal that is pulsating.   

 

You get annoying humming when you run straight DC locos on DCC power.    So maybe the decoder is not passing on straight DC to the motor.

Max, which model of Loksound decoder are you using?

 

Also I have not found the need to add an idler on stock Weaver drives, but every Weaver Pittman drive I have seen had cracked sprockets causing very rough running and high load on the motor each time the crack comes around.

 

I use most of the tips and tricks here for smooth running:

https://bobsobol.smugmug.com/T...018664&k=jxLWMHq 

 

HTH    

 

Pete

 

 

Last edited by Pete M

Hi Pete

 

I'm using a Loksound Select.  A commonly used decoder by members of the Loksound group, for O scale locos.  I've also used V 4's, but not this time.  I record my own sounds and make sound projects, so I'm very experienced with them.

 

I'll be very disappointed if it has cracked sprockets, as it's new; straight out of the box.  I'll tear it down and have a look anyway.

 

Thanks for the link.  I'll have a look.

 

Is there anywhere I can get help with my earlier question about the photos?

 

Cheers

 

 

Originally Posted by Simon Winter:

There is a guy who goes by bob2 on the forum that knows quite a bit about Pitmans. Some are better suited than others. Hopefully he will turn up.

 

Simon

Hi Simon

 

That guy could be the one in Pete's link.  I had a look at it.  Lots of good info there Pete.  If/when I sort the BEMF issue, I'll be having a closer look.

 

Cheers

To answer your question about photos, try this.  Within your posting box, type a little info and then add an attachment here, being sure to check the box so that all pictures are added within text before completing that upload.

IMG_8233

Then, type a little more info and choose to add another attachment, doing all the same things you did for the first attachment.

 

IMG_8244

After each attachment upload, you have to remember to check the box about inserting photo or video into the text of you message, and then click the "Finished" box which puts the picture into the message and takes you back to the Post Message or Post Reply screen.  Then, hit your keyboard "Enter" key and add more text as you choose.  Finally, remember to scroll down to the bottom of the Message or Reply box and press "Submit," and your info should look like above.

 

I used some pictures of our 30th anniversary vowel renewal in Hawaii last October to demonstrate.

 

Chuck

Attachments

Images (2)
  • IMG_8233
  • IMG_8244
Hi Max,
 
Not the same Bob. Both are very knowledgeable. Bob Sobol more on the Diesel modelling side from what I've learned online. I have also learned a lot about Pittman motors from 2 other experts: Jay Criswell and Rod Miller. 
 
For example I learned that earlier Pittmans used Alnico (conventional) magnets. Later models used modern Neodymium magnets. I can speak from my own experience that the older ones are current hogs, the newer ones much more efficient. As I recall, the Alnicos have a "1" as the third digit in the model number e.g. 8514 as found in many Weaver drives. The rare earth magnet ones have a "2" as the third digit.
 
I have been frying decoders in O scale since 1994 but I only have 1 Loksound. I have been working with Digitrax and then NCE with DSX sound added, then recently Tsunamis and now TCSWOWsound. So much to learn! 
 
The gears Weaver used were made a long time ago and were a press fit on their shafts. They crack as the plastic shrinks. This happens anyway, even if the loco was never out of the box. I have 7 Weaver drive sets (some in other brands of engine) and all top sprockets were cracked when I got them, and several bottom sprockets too.    
 
Re the humming, I am trying to say that the cracked gears may be causing it. if the Loksound works by adjusting PWM to attain constant speed, then the cracked gears are loading up the drive several times per wheel revolution. Then if the Loksound drops the PWM frequency way down into audible range to try and generate enough torque to overcome the gears, that's when you get the hum.
 
If the top sprockets are cracked it's happening several times per wheel revolution as the gear reduction happens at the axles on a stock Weaver drive. 
 
I have an early NCE D408 which has user adjustable PWM frequency. You can take it up to about 16kHz and not hear any motor hum. But the loco wouldn't pull the skin off a rice pudding! Turn the PWM down to a few kHz and it will pull the side off the building. But it hums so loud it's unbearable.
 
Is your DC setup smooth power or pulsed?
 
I may be way off base here as I don't know how the Loksound works, but just in case it helps, I really would check for cracked gears first. You can do that easily just by taking off the shell and manually turning the driveshaft from the motor. You'll feel a hard "notch" every 1 turn of the drive shaft, and see the chain climbing out of the sprocket each time as the teeth each side of the crack are too large a pitch.
 
HTH
 
Pete 
 
 
Originally Posted by MaxSouthOz:

Hi Pete

 

I'm using a Loksound Select.  A commonly used decoder by members of the Loksound group, for O scale locos.  I've also used V 4's, but not this time.  I record my own sounds and make sound projects, so I'm very experienced with them.

 

I'll be very disappointed if it has cracked sprockets, as it's new; straight out of the box.  I'll tear it down and have a look anyway.

 

Thanks for the link.  I'll have a look.

 

Is there anywhere I can get help with my earlier question about the photos?

 

Cheers

 

 

 

Last edited by Pete M

Max,

I am not running decoders I just running a remote control that basically is a decoder made by GML.

Crack gears will make hesitation at any speed, but more noticeable at low speeds.

As peter M say, rotate it manually and also disconnect the drive shaft from the motor and test the motor empty.

 

Andre. 

 

Pleased to help Max. I have a few scars from trying to get these drives to run really smooth over the years, better if the collective knowledge here can save you some of the pain... 
 
Good that your DC is smooth. My guess is it was just delivering more Amps to get you over the load spikes but you wouldn't know that audibly, you'd need an Ammeter to tell.
 
Good luck with your explorations!
 
Pete
 
 Originally Posted by MaxSouthOz:

Thanks, Andre.

 

At least I will know what to look for, now.

 

I'm off to do some surgery. 

 

Cheers

 

The locomotive may be new to you but Weaver quit making that horizontal drive about 15 years ago so not really new.  My guess is that PD Hobbies http://pdhobbyshop.com is now the owner of that drive mechanism as they have been selling and supporting it ever since.

 

The idler idea has been around for a long time for the reasons you cite and it would be nice if Pat @ PD would make one available, but not so far.

Last edited by rdunniii

"I'll be very disappointed if it has cracked sprockets, as it's new; straight out of the box."

 

  I'd be surprised if it doesn't have cracked gears. Unless someone has changed them it's almost a certainty. Get replacements and learn to install them is the normal solution. These drives are very easy to troubleshoot and repair.......DaveB 

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