Reproduction UC Track availability?

[Lynn Eades]

The Aussie track uses a shorter straight plain pin. At the inner end, the hole is smaller. This allows the pin to be punched out, whilst being retained. The other end has a recess with a groove in it. This end is lead plugged. Punching the lead plug in, expands the plug into the groove, thus retaining the pin. The lead is soft enough to fail, when the pin is punched from the inner end.
With English or Canadian track(essentially the same specs) the pins are as per your description. The track sections are assembled into 21 link sections, and joined with pins, that are located with a washer, and split pin I have a number of these pins, and can supply a sample if you wish.
Be aware that the track has quite a tolerance between the links, and requires this side clearence, to allow the track to displace sideways, allowing the machine to turn. The double bogie assembly moves 3/8" each way from centre. I would estimate that the track would need to achieve this over about 16 links (the number of links between the front bogie, and the 2nd bogie wheel)

[matt_mcleod]

Hi Mr Eades,
Many thanks for the extra detail. Yes, I was aware you steer a UC via the bogie, not like an earthmoving machine which is turned via track speed differential.

We'll work on the assumption that the sample link we used for the pattern will give us the correct clearances to permit the UC to turn, but will verify with samples, if the project goes ahead.

I'd appreciate a sample, but some measurements with a vernier caliper would suffice if you can help. Otherwise, I'd be he happy to purchase a pin/washer/split pin from you to ensure we have accurate basis for any reproduction. Let me know what works best for you.

Thanks again,
Matt.

[Lynn Eades]

The nominal length of the pin, from the shoulder under the head is 250mm (of 22 pins, they vary from 248mm to 253mm.
Shoulder to centre of split pin hole is 246mm to 247mm.
I have one pin wth a change of colour at the 241mm mark.
The diameters vary around 0.4375" (7/16")
Some are marked "L" (maybe Leys U.K.) others are marked "V.P 1943",one is "N 2/3, and others are plain.
Some are black, while others are bright steel.
Anything else just ask.
Oh, and Matt, Red, Lynn, or Bluebell will do fine.
,

[Philliphastings]

Hello Matt and welcome to the forum. What you are proposing is indeed exciting news for non Australian Carrier restorers...

Cheers

Phill

[RichardT10829]

Yep you got my pulse racing if there is anything i can do to assist let me know

[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