4 wheel lead truck centering devices

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Rob Gardner
Posts: 463
Joined: Sun Oct 23, 2005 9:27 am
Location: Newbury, OH

4 wheel lead truck centering devices

Post by Rob Gardner »

4 wheel lead trucks were originally built with one of multiple types of centering devices. In the hobby, swing links and heart rocker are fairly common. However, one of the more modern designs utilized two parallel rollers that would ride up and down inclined planes with teeth on the inclined planes engaging notches on the rollers to maintain alignment. Does anyone out there have experience and photos how they might have built this style device? Would like to build this per the original Lima C&O J3a Greenbrier had these and that is what I am building.

Thanks in advance,

Rob
JKreider
Posts: 311
Joined: Fri Oct 07, 2005 8:38 pm
Location: Redlands, CA

Re: 4 wheel lead truck centering devices

Post by JKreider »

Two-wheel pilot trucks, such as on the Berkshire, also used the roller and inclined plane centering device.
This is what I used on the Berkshire and they have worked out quite well.
I modified the design somewhat in regard to the location of the teeth and corresponding slots on the rollers to facilitate machining but the operating principle is the same.
I designed for 25% of the weight on the truck as the centering force.
I do have drawings for the parts as used on the model and I must have some pictures around here some place.
If I can’t readily find the pictures I am going to remove a pilot truck from one of the Berkshires at RLS during the next two weeks so I can take pictures at that time.
Please let me know if this would be of interest to you and I’ll get you some pictures.
I have made CNC runs of these parts but I am out of them right now.
Roger Goldman might have used the roller and inclined plane on his Challenger but I don’t remember. Roger might be another avenue for you for the design/parts on this. He makes good stuff.
Jim Kreider
Rob Gardner
Posts: 463
Joined: Sun Oct 23, 2005 9:27 am
Location: Newbury, OH

Re: 4 wheel lead truck centering devices

Post by Rob Gardner »

Jim, that would be most helpful. Thanks in advance.

Rob
SF2900
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Joined: Thu Dec 02, 2010 4:40 pm
Location: Sacramento, CA

Re: 4 wheel lead truck centering devices

Post by SF2900 »

Rob - Ed has a centering device of that type on his Z-8 Challenger and suggested we use that method for my engine. I believe he uses cam followers for the roller devices. There are no teeth on his - he just has the folowers rolling on inclined planes which are surrounded by a perimeter flange that acts as a stop. I will talk to Ed next time I see him to see if he will post further info.
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NP317
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Joined: Tue Jun 24, 2014 2:57 pm
Location: Northern Oregon, USA

Re: 4 wheel lead truck centering devices

Post by NP317 »

Here's a photo of the heart link centering set up on the lead axle of my 90-ton logging Mike.
The design is pretty much straight Baldwin. Not my design.
~RN
Lead truck on 90-ton 2-8-2
Lead truck on 90-ton 2-8-2
JKreider
Posts: 311
Joined: Fri Oct 07, 2005 8:38 pm
Location: Redlands, CA

Re: 4 wheel lead truck centering devices

Post by JKreider »

Rob:

Here's my design of the Berkshire pilot truck centering device.
Of course the upper mating teeth are on the truck bolster.

Jim Kreider
Attachments
Berkshire Pilot Truck 001-3.jpg
Berkshire Pilot Truck 003-3.jpg
Berkshire Pilot Truck 004-3.jpg
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Jim_Nolan
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Location: UK, North of the wall
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Re: 4 wheel lead truck centering devices

Post by Jim_Nolan »

This is the version fitted to the 25NC I had the racks CNC’d years ago now I would just RP em and cast in Bronze or something. The rollers were RP’d and cast so don’t know why I did not do the whole lot that way.

Image


At the time I had never heard of them so was quite reassured when I found out Jim had used them.

The real thing

Image

Jim
www.northernsteam.com
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