Reproduction UC Track availability?

[matt_mcleod]

Hello gents,
Thankyou for the public and private messages of welcome and support for our investigation.

I had a look at a couple of carriers yesterday, both for the tracks and to help a friend draw up the front armour plates for reproduction (if anyone is interested in these drawings I will send copies when they are finished).

I also re-measured a couple of brand new links to clarify the pin bores. My measurements would indicate the bore in the link is nominally 0.5mm greater in diameter than the maximum pin diameter.

ie (according to Nigel Watson's text) the new pin diameter is allowed to vary between:
Max 0.437" (11.10mm)
Min 0.432" (10.97mm)

My measurement of a link bore (taken three times) averaged out to 11.6mm. If anyone has a link lying around and can take a measurement to confirm this as a suitable target diameter for the bores - that would be great.

On the topic on pins, I had a discussion with our patternmaker who has contacts at Ajax Fasteners here in Australia. We will ask them for a quote, and have also sent a pin drawing to China.

We have had a number of discussions regarding pin materials and pin retention and would be interested in some feedback from the forum. As was mentioned above, I understand the pins were case hardened along "most" of their length. This would have been done for wear resistance, but still allowing the softer end to be peened over.

Frankly, heat treating pins adds another sub-contract operation which means more cost. We have considered using a high carbon steel like 1040 in an attempt to maintain some surface hardness without adding another manufacturing operation. With the expected use of restored carriers in mind (ie they are not in war service) we propose this will provide a cost-effective alternative.

With respect to pin retention, there are a number of options. The NOS track I inspected today used a small collar on the straight end and appeared to be simply peened over with a hammer. Nigel's book shows factory tracks having a domed, riveted head. There is also mention of "welded caps". Service track sections are joined with split pins. Aussie tracks use lead plugs.

Here are the pros and cons of each (from a manufacturing perspective):
[1] Collar/peened: Pros - cheap and easy, Cons - lots of labour, assumes 1040 high carbon steel can be peened in this manner (we'd have to make a sample pin and try it)
[2] Domed/riveted head: Pros - very strong, Cons - needs special tooling to achieve, would have to sub contract and ship big heavy link sections around
[3] Welded Caps (using a collar as per [1] and TIG welding the collar to the end of the pin): Pros - strong, relatively cheap, Cons - can't think of any
[4] Split pins: Pros - easy to assemble/disassemble, could be assembled by end user, pack tighter in crate for cheaper shipping, Cons - Retention relies on a small split pin
[5] Lead plugs: Pros - can't think of any, Cons - another part, another material, more cost, questionable whether we can reproduce the dimensions and achieve acceptable pin retention.

On the topic of strength using split pins, I don't believe this is valid option. When turning the carrier, the track is curved and hence the forces generating the turn are transferred to the washer and therefore the small split pin is loaded in shear. This would be acceptable for joining service link sections, but I would consider this poor engineering practice if used to join all the links.

My preference is for [3] Welded caps, but interested in the feedback from members. If this was selected and if the repro track manufacturing goes ahead, I would propose service link sections would be pre-assembled and stacked in a custom-built crate for shipping. End users would then assemble the service link sections with split pins as per original supply.

Anyway, enough for today. Would appreciate any thoughts, feedback or comments.

Regards,
Matt McLeod

[cantankrs]

Hi Matt,

Well done giving replacement track this detailed investigation!

I would like to offer a few comments, set out below.

Originally Posted by matt_mcleod

...to help a friend draw up the front armour plates for reproduction (if anyone is interested in these drawings I will send copies when they are finished).

From memory I think RichardT10829 and also Martyn have done a lot of work in respect of armour drawings for English/Canadian Carriers. If that's news then search MLU or you might wish to PM Richard to compare notes.

Originally Posted by matt_mcleod

[5] Lead plugs: Pros - can't think of any, Cons - another part, another material, more cost, questionable whether we can reproduce the dimensions and achieve acceptable pin retention.

I've seen NOS lead plugs and while they're another part, the ones I've seen were simply a cylindrical slug of lead. Deforming them into the end of the track seems to be the effort required for assembly. I do admit however that I'm not familiar with what shape the track link takes that accepts the lead plug. I don't know if it's as cast or machined.

Originally Posted by matt_mcleod

On the topic of strength using split pins, I don't believe this is valid option. When turning the carrier, the track is curved and hence the forces generating the turn are transferred to the washer and therefore the small split pin is loaded in shear. This would be acceptable for joining service link sections, but I would consider this poor engineering practice if used to join all the links.

I've reread this and see your point about using it only for joining such as a master link in a drive chain. But my observation, if I understand its function correctly, is that the interlocking of the track links defines the total sideways movement of adjacent track links, so if the pin is long enough (and not seized in either track link) then the washer or retainer should not receive load that would shear the pin. The question to ask seems to be is there a history of these pins being sheared during operation?

Regards

Alex

[Lynn Eades]

The lead plug is easy. I cant really remember which calibre, but some of the guys use cast lead bullets, which are easy to make(.45 cal?).
Re retention with a split pin, it worked in service, and I concur with Alex, that infact there is virtually nill end load on the pin in normal use.
A thought, that sits in the back of my mind is that anyone wanting repo track, would want it to look original.
The track pins I have, have different heads, some appear to be made like a rivet (The pin being held, and a head formed by hitting it) some look like they are rolled( the head appears to be formed by rolling the material back on its self, and you can see in under the head from the pin end, around the pin circumference)
I believe you are headed in the right direction, with your welded head option.
If your run of English/Canadian track is a success, do you intend to do the Aust. pattern track?
I have just looked at an Australian manual, and it states the track links are made of malleable iron.
The track displacement is 5/8" not 3/8" as I previously stated.

[ron]

Hi Lyn. 38 wad cutter bullets are perfect if cast in pure lead, regards Ron

[Lynn Eades]

I should have known you'd be the man.

[cantankrs]

Mostly off-topic story. But related to imported foundry work. My Dad used to work for a firm down in Perth that in the late 60's imported single cylinder stationary diesel engines similar to a Lister design that were made in India. They proved to be OK engines, certainly the mk2 with the better crank/bearings was very good. My Dad actually bought one 20 years ago second hand cos he admired them for their price. They were beautifully finished on the outside, but still had casting sand in places inside! So the workshop fellas in Perth had to strip every one and clean them out thoroughly and reassemble them before sale.

Regards

Alex

[Perry Kitson]

I had a couple of Canadian UC track pins tested for composition a number of years ago, here is what I found,

Ni 2.31%
Mn 1.53%
Cr .31%
Fe 95.06%

case hardened 56-58 Rc.

Hope this helps.

Perry