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Offline HO Collector  
#1 Posted : 18 April 2020 15:24:48(UTC)
HO Collector

United Kingdom   
Joined: 21/02/2016(UTC)
Posts: 195
Location: Just north of London
Hi guys.

Need some advice.
I am servicing this Crock. for a member on the forum. The model has a running problem. When trafo. voltage reaches a certain level the reverse unit activates, front and rear light becomes bright and the loco stops with loud buzzing noise. I have replaced the old reverse unit spring (in German Spring=Feder) with a new P/N 7194 (from my stock) that seems to be the same length (i.e. same strength), now the problem has changed. When pressing the trafo knob in order to change direction the loco starts running fast for a short distance (about 40cm) before direction is changed which tells me that the spring is to powerful. I have looked at the parts list https://static.maerklin....68f456a6651434542264.pdf but the spring is either missing or I can't see it.

Does anyone knows what is the correct P/N or maybe have an idea how to overcome this issue?

Thanks

Ben
Offline HO Collector  
#2 Posted : 18 April 2020 18:52:24(UTC)
HO Collector

United Kingdom   
Joined: 21/02/2016(UTC)
Posts: 195
Location: Just north of London
I have thought that I solved the issue above by manipulating the spring strength as the model ran perfectly ok when the body was off, then, I have put all 3 body parts on and it refused to change direction, removed the body part above the reverse unit and it ran nicely in both directions. Then during operation I have noticed sparks (green if makes a difference) at the electric contact breaker of the reverse unit, checked for oil or dirt in the area all is clean. After several attempts with/without the body I have return the spring to its original strength but now the reverse unit refuse at times to move and turn the cams shaft and the model just buzz ,turning the cams shaft by hand just cause the loco to buzz with lights on, it will travel only in one direction. All wires are connected and nothing was done (i.e. by dismantling) to cause the problem. Is it possible that the problem is due to a worn reverse unit (item 60 in the ling above)?

I can't think on anything else and will be happy and thankful for any idea.

Thanks

Ben
Offline Unholz  
#3 Posted : 18 April 2020 18:59:04(UTC)
Unholz

Switzerland   
Joined: 29/07/2007(UTC)
Posts: 1,391
Location: Switzerland
The German word for the part you are looking for is Schaltschieberfeder. AFAIK, there was only one variety ever produced, with the original part no. 7194, as you have correctly stated.

Manipulating the spring strength should normally be the correct manner to solve the problem. But from what you describe in your second posting, something must be obstructing the reverse mechanism - or then it is clogged with some dirt. Make sure that the "Schaltschieber" moves freely, without any wires interfering or being pressed against the reversing unit when the body parts are put back on. Perhaps a tiny drop of oil on the moving parts will help.
Offline JohnjeanB  
#4 Posted : 18 April 2020 21:57:44(UTC)
JohnjeanB

France   
Joined: 04/02/2011(UTC)
Posts: 3,084
Location: Paris, France
Hi

The activation of the reverse unit at high speed points to adjustment of the reverse spring. The spring needs to pull more
The 3015 called for a special inverser relay because it has to be mounted horizontally which adversely affected the functioning of a ratchet reverse relay (the standard one). So says Märklin which used drum reverse on these locos (as shown on the exploded view).
On my 3015 I mounted a brand new standard Märklin relay and it was working OK.
Cheers
Jean
Offline HO Collector  
#5 Posted : 19 April 2020 13:32:04(UTC)
HO Collector

United Kingdom   
Joined: 21/02/2016(UTC)
Posts: 195
Location: Just north of London
Opened the model this morning removed the body parts and test run it, worked ok in both directions. Fitted the front body section above the reverse unit and it stopped changing direction. Examined the body part internally and have noticed that some holding pins of the hand rail are too far out, hence might touch the reverse unit so this was sorted, yet the model refuses to change direction with or without the body sections fitted.
When pressing the trafo knob sometime the magnet pulls the arm and sometime not, a drop of oil was applied and overflow was cleaned, however when the arm is being pulled and the cams shaft rotates the model will not reverse but will keep on buzzing. I have also noticed that when the cams shaft rotates there is an horizontal movement i.e. in the direction of back to front, can't remember seeing it on my 3015 or 3025s.
Will try the spring again and then???

Thanks

Ben
Offline JohnjeanB  
#6 Posted : 19 April 2020 15:26:25(UTC)
JohnjeanB

France   
Joined: 04/02/2011(UTC)
Posts: 3,084
Location: Paris, France
Hi
This points to the reverse relay used in the fifties with a drum and 4 positions:
- forwards
- stop with lights
- reverse
- stop with lights
So your loco is 1958 or earlier
PS: never oil the reverse relay IMO
Perhaps the relay poor functioning is due to excessive pressure of contacts on the drum or loose wire coming in the way of the relay.
Cheers
Jean
Offline HO Collector  
#7 Posted : 19 April 2020 19:41:22(UTC)
HO Collector

United Kingdom   
Joined: 21/02/2016(UTC)
Posts: 195
Location: Just north of London
Originally Posted by: JohnjeanB Go to Quoted Post
Hi
This points to the reverse relay used in the fifties with a drum and 4 positions:
- forwards
- stop with lights
- reverse
- stop with lights
So your loco is 1958 or earlier
PS: never oil the reverse relay IMO
Perhaps the relay poor functioning is due to excessive pressure of contacts on the drum or loose wire coming in the way of the relay.
Cheers
Jean


Hi Jean

Thank you.
Yes, there is a drum that turns around (with a small horizontal movement) and the sequence that you mentioned is correct, yet I don't think that it is 1958, it seems to be a later model but who knows.
Anyway, the drums moves ok and all wires are connected properly but the issue is so intermittent and every time there is another. Now the model will not reverse, with or without the body parts attached. I don't know what to look for next.

Thanks

Ben


Offline mvd71  
#8 Posted : 19 April 2020 19:58:17(UTC)
mvd71

New Zealand   
Joined: 09/08/2008(UTC)
Posts: 1,710
Location: Auckland,
Maybe time to post some photos so we can see everything you are seeing?
Offline Crazy Harry  
#9 Posted : 19 April 2020 20:39:32(UTC)
Crazy Harry

Canada   
Joined: 18/11/2008(UTC)
Posts: 476
Location: Oakville, Ontario
On the top (normal orientation) of that type of reverser is another contact (see red oval in attached picture). As the solenoid moves a little nub raises the central leaf to break contact there - thus the motor doesn't see the reversing voltage and shoots away at high speed. Maybe your contact there is dirty and therefore you have inconsistent or no operation. Be careful cleaning and adjusting this contact, it is fragile. I had to replace the reverser in BR44 steamer (3047) that had a similar problem and I broke that contact trying to bend it to make it work.

3015 Reverser.png

Cheers,

Harold.
Offline JohnjeanB  
#10 Posted : 20 April 2020 13:28:18(UTC)
JohnjeanB

France   
Joined: 04/02/2011(UTC)
Posts: 3,084
Location: Paris, France
Hi Ben
The relay I am talking about (4 positions) is here on the left.
The picture below is from Märklin spare parts documentation 1955 1958
UserPostedImage
The one shown by Harold is 2 position and in locos from 1975 Picture is from Märklin in 1975 (Spare part documentation)
Cheers
Jean
Offline kiwiAlan  
#11 Posted : 20 April 2020 13:39:03(UTC)
kiwiAlan

United Kingdom   
Joined: 23/07/2014(UTC)
Posts: 8,082
Location: ENGLAND, Didcot
Originally Posted by: JohnjeanB Go to Quoted Post
Hi Ben
The relay I am talking about (4 positions) is here on the left.
The picture below is from Märklin spare parts documentation 1955 1958
UserPostedImage
The one shown by Harold is 2 position and in locos from 1975 Picture is from Märklin in 1975 (Spare part documentation)
Cheers
Jean


OK, if the unit he has is the one on the left, then there is some adjustment of the spring tension possible. The screw and lug, items 11 and 12, allow the spring tension to be increased of decreased slightly to take up variations in the the springs. There is some black magic in getting the tension just right so the reverser pulls in on a reversing pulse, but doesn't on maximum speed.

Offline HO Collector  
#12 Posted : 20 April 2020 23:06:38(UTC)
HO Collector

United Kingdom   
Joined: 21/02/2016(UTC)
Posts: 195
Location: Just north of London
Good evening.

First, thank you for your help, I have returned late after long day at work and ready to go to bed.
The drawing by Harold is the correct part, I haven't looked for adjustment screw but will have a second look, hopefully tomorrow, then will post a photo per MVD71 request.

Good night

Ben
Offline HO Collector  
#13 Posted : 20 April 2020 23:12:19(UTC)
HO Collector

United Kingdom   
Joined: 21/02/2016(UTC)
Posts: 195
Location: Just north of London
Crazy Harry

Didn't adjust this contact, too dangerous, as you said, once touched... However, I have cleaned it with #4000 paper (not too much) as it was sparking.

Ben
thanks 2 users liked this useful post by HO Collector
Offline HO Collector  
#14 Posted : 21 April 2020 22:50:54(UTC)
HO Collector

United Kingdom   
Joined: 21/02/2016(UTC)
Posts: 195
Location: Just north of London
Some photos as promised.

crock 2.jpgCrock 3.jpgCrock 4.jpg


The top photo shows the original spring.
Middle and bottom shows the contact that opens when the trafo knob is pressed which also was observed to spark during operation. It was cleaned by using r #4000 paper.

Ben
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