Spicer Reverse Solenoid issues again

[Fredward]

After returning from our 2,600 mile trip last week I'm digging in to why the reverse solenoid won't let me get into reverse anymore. (Imagine driving 1,100 miles without reverse.) In the past two years I have replaced the Solenoid and the actuating relay. After which it worked fantastic. The Solenoid tries to actuate but can't quite pull the plunger on the side of the tranny.

I'm suspecting ground is the problem, as I can manually engage reverse and I can hear the solenoid trying to actuate. So I'll do my electrical troubleshooting but just wondering if anybody else has stumbled on this issue. This is on a 4 speed spicer on an MC-5A
Fred

[robertglines1]

Maybe dirt on selonoid plunger or surface rust from moisture/or road dirt...glad to see you made it back from great adventure..keep your steam up. Bob

[JackConrad]

Fred,
 I think there are 2 coils inside the solenoid, an engaging and a holding.  Might check both with an ohm meter to rule out a bad solenoid.  Jack

[Sam 4106]

Hi Fredward,
We had a similar problem on the 4 speed spicer in our 4106. I too replaced the solenoid and it worked for a while. The next time it quit working I put a bungee cord from the arm the solenoid plunger attaches to and a bracket on the transmission with just a little bit of tension on it. (A light spring may also work.) Reverse engages every time now. It may look like a Rube Goldberg setup but it has worked for years. That might be an easy fix for you as well.
Good luck, Sam MC8

[bevans6]

The manual says that the reverse solenoid should draw 30 amps nominal when both coils are energized and 4.5 to 6 amps after it is thrown and the hold-in coil is the only one energized.  A single relay and circuit goes to the solenoid, and the two coils are separated internally.  The contact points that disengage the pull in coil must open when the plunger has reached the limit of travel, you should be able to suss that out with an ohm meter.  This is adjusted by altering the length of the adjusting bolt on the linkage.  The basic idea is that if the linkage is adjusted wrong, the solenoid will not travel far enough to disengage the pull in coil, it will work for a while and then fail.  the manual has a routine for adjustment.

edit:  it also says that you need to release the switch as soon as the shift into reverse is made, you don't hold the switch down as long as you are actually in reverse.  But you probably knew that already!  

Brian

[Jerry32]

Had trupble with mine on a 4905 but was loose connection inside the solinoid. Jerry

[LUKE at US COACH]

Hi Fredward and Folks:

You may or may not be aware that that the linkage on the solenoid is adjustable to compensate for wear and aging of the coil.  There is a bolt and 2 nuts on the linkage.  One of the nuts locks the adjustment that you make. This adjustment allows you to increase or decrease the arm throw.

I Hope this HELPS!!!

Happy & SAFE!!! Bussin' to All.

LUKE at US COACH

[Fredward]

Great information guys. I wonder if I misadjusted it when installing it two years ago. So now maybe I burned out either the "pull in" coil or the "hold" coil?

When testing current draw can I test it on the bench or does it need to be installed with the actual load attached?

I'll check the manual tonight too.
Fred

[bevans6]

You can bench test it.  You may have to be quick to test the pull-in mode unless you limit the travel.  There are points inside that act as a switch, as soon as it reaches full travel the points open and disconnect the pull-in part of the coil.  I would do a resistance check, measure resistance of the coil closed, then when you pull it full open, should change.  less resistance when both coils are in play, higher resistance when only the hold coil is connected.  DC resistance should therefore be 24v/30A = 0.8 ohms when the solenoid is closed, and 5 ohms when it's fully open and the pull-in coil is switched out.

edit:  Here is something else to check.  The feed through the relay to the solenoid is through a 15 amp breaker.  Since the solenoid is supposed to draw 30 amps when both coils are energized any delay will blow that breaker which is probably an auto reset so it keeps trying to let it work.

this was a good question!  I always wondered how the reverse solenoid worked!   

Brian

[4104GA]

 I saw a 04 that had a brake can installed where the solenoid was mounted and used air to shift to reverse. It
worked  so if all else fails this works.  Never had a problem with my solenoid.

[Fredward]

I tested voltages tonight (the VOM I had along on the trip wouldn't measure voltage, only Hz) and it looks like everything is in order. SO I guess I'll pull the solenoid and bench test the coils as suggested earlier. Boy thats a fun thing to get at! I can get it out from the curb side engine compartment I guess. The access panel in the floor doesn't grant access. But otherwise I probably should have run it up on the blocks and crawled beneath. I hate going under there.
Fred

[Fredward]

So I finally got back at it yesterday. Installed the new solenoid but it doesn't seem to work any better. Now I may not have it adjusted correctly and I will borrow a meter for testing current draw for that purpose. And I will get it on Monday. The old solenoid did test bad.

But now I'm wondering if there could be something mechanically wrong with the reverse plunger making it harder for the solenoid to actuate? I can pull it out manually by prying. Is there something that wears on the plunger inside the transmission that could be the cause? I'm going to work on it again this afternoon so I just thought I'd throw that question out there.

Fred

[Fredward]

Fixed it.
The linkage wasn't adjusted properly. I shortened it up and then tested current draw when fully engaged. 7.6 amps at 24 volts. Guess that means the pull in coil is disengaging properly when the solenoid is at the full extent of its travel.

I backed up all over the place tonight. Pulled it outside and pressure washed the engine; got all the road grime off the back end of the coach. Life is good again.

Now I've got to look into the leaking rear end problem. It used a lot of gear lube on the trip.

Fred

[robertglines1]

feels good to win one its just about time for steam shows;been to school yet? Glad your problem is over and I'm sure many others learned from your experience...Good bussing Bob

[Fredward]

Bob,
Our Steam School is at Rollag Father's Day weekend.
Could you send me the link to your engine again?
Fred