More Help Needed.....Turntable track power question

 I’m not sure exactly how the Bowser bridge’s rails are powered. If I’m reading your post right. You have an engine running on DCS.  You are then shutting it off with the handle of the ZW when it reaches the center of the bridge ? The engine should still have sounds for about 8 seconds from the battery. You state the tracks have voltage through a meter. It seems like a complicated process to turn an engine if your doing it this way. I would wire everything through the TIU and try to run it with DCS. 
 I would leave an engine on the bridge. Do what you need to do to get it to come up silent and start up with the remote. I would then rotate the bridge while looking at the signal strength on the remote. I would live with mostly 7’s or better through most of the test. Run the wires right to the bridge only. This will insure the results you are getting are dealing with just 1 piece of track.

Two connections;

1. Track power:  via the center thrust bearing and rotating bridge. 

Thrust bearing.  

Rotating bridge shaft with enhanced electrical contact.  Note the wire on the left end, of the T-bar, which attaches to the center rail. 

This assembly is powered and should be isolated from any metal that would short or ground track power. 

2. Common:  Pit rail and roller assembly attached to the two out side common bridge rails. 

Common wire needs to be attached to the pit rail.

The bridge boggies  pick common power from the pit rail.

Common power from the boggys to the bridge outside rail, Black wire center of picture. 

Bowser TT's, and Upgrade kits should work with the same bridge track wiring.   Cleaning the pit rail and boggy wheels may help.  Good clean pit track and contacts should work with either TMCC or DCS.  

Bill from Rochester posted:

... 

The issue I am trying to resolve is I can run an engine on to the bridge, bring it to a stop off the handheld and then start to rotate the bridge. Before the bridge makes a half turn or so the engine shuts down.

I see two possible causes for the shut down. The first is that the bridge power loses contact during the rotation.

... 

Before dealing with any DCS issues, I'd first verify the integrity of the wiring to the bridge track section.  Connect the voltmeter to the bridge track and rotate the turntable back and forth several times looking for momentary drops in power.  Or if that's impractical, put a lighted passenger car on the bridge and look for flicker while rotating the turntable.

As Dave points out, DCS engines have a battery which can ride-thru interruptions in track power as well as power the sounds for seconds when track power is lost. This might be masking a wiring issue to the bridge track section.  

My guess is 20+ years in storage might have "gummed up" something in the electrical slip-rings or wipers that contact-cleaner or whatever can clean up.

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After you resolve the above, as Dave suggests you should run wiring to the bridge and roundhouse sections thru the TIU.  I realize you were able to control the engine on the bridge with it wired directly to the transformer.  This is technically possible but never recommended as it drastically decreases the DCS signal levels used to communicate between TIU and engine.

Bill from Rochester posted:

My second thought is that because of connecting power directly to the transformer and bypassing the TIU, the engine shuts down after 10-15 seconds. The correction  would be to rewire so that the power to the bridge is on the output side of the TIU.

 

Bill, it looks like you already found your solution.  Since you will want the turntable track powered through the TIU anyway, try that first.

Thank you every one.

Looks like I need to rewire through the TIU. I will also clean the bogie wheels and support track which is the ground. I had applied oil to the wheels to make the bridge swing more easily. I also greased the center shaft, so may have to look at that . Now, off to the rewiring.

Regards,

Bill

I also ave one of these old Bowsers, repowered with the Ross Drive.  Power is fed through the center shaft and the turntable track.  Power is through the TIU, on a channel that feeds one of the two mains.  Engines can be left on while turntable is turning.

Verify that the turntable track is a solid connection all the way around.  There may be gaps, which can be filled in with solder. 

Good afternoon, everyone.

I am looking for more guidance on my turntable track power issue.

I started by cleaning the outer ground rail... it  was pretty grimy.

Next I rewired the power so that the power to bridge track comes directly off the output side of the fixed #2 connection of the TIU. Using a voltmeter shows the bridge track to have just 11-12 volts. The approach track to the turntable has the normal 17-18 volts. As such, when the engine rolls onto the bridge track it shuts down (normal shutdown sequence). I took no steps to shut down the engine.

This makes me think that the grease I applied to the center shaft may be causing this voltage drop off. I used Super Lube Synthetic grease. The package indicates it is an excellent dielectric, so I assume it is a conductor but I may be wrong in this view.

In yesterday's response MikeCT showed a picture of the center shaft with a thrust bearing. My turntable lacks a thrust bearing, so I may need to locate one to allow the bridge to turn more freely. Not sure if this could impact the outer wheels contacting the ground ring.

I am reaching out again for any additional guidance, before I start cleaning the grease off the center shaft.

Thanks again for your responses.

Regards,

Bill

  Can you make up a good quality wire to plug into the TIU.  With an alligator clip or a track pin at the other end. Remove the center rail wire from the TIU and plug in your test wire. Clip the other end onto the bridge track. Re check your voltage and see if it improves. If it does. Rotate the bridge a bit and see if it remains consistent. If there is no change. Switchover to the outside rail and check. You should be able to slowly track down your bad connection.

Bill, sorry to have to say it, but "dielectric" means insulator.  You say the voltmeter shows 11-12 volts.  Is there any load, such as a loco on the turntable?  Should be.  If voltage drops to near 0 with load, sheck voltage at the spot where the lead connects to the center tube.  If that's same as approach track, the grease is the issue.  If it's the same voltage as the bridge track, there's a bad connection upstream.

Success!

I removed the bridge from the pit and wiped the grease from the center shaft and the retainer tube for it.

Before replacing the bridge I measured the voltage at the point where the power line attached to the turntable. It was the normal 17-18 volts. After replacing the bridge the voltage on the track stayed at 17-18 volts.

I successfully ran an engine on to the bridge and it stayed powered up. Also able to fully rotate without loss of power to the engine.

So it looks like the grease was the issue.

Thanks to all that offered suggestions, they are most appreciated.

Regards,

Bill