Project PHOENIX

[Bob Moseley (RIP)]

Hi all - discussions last night with my guru, Dingo Man, led us to Mike Cecil's book on Carriers. Whilst discussing the Tracked Truck we discovered that its drive sprocket was a 42 tooth sprocket. Colin and I had calculated that the Phoenix sprocket was 43 tooth, but maybe it could be 42 tooth. Next question, was any tracked vehicle fitted with a 42 tooth sprocket so that GM could utilise that as opposed to manufacturing a new one. Am I correct when I say that the Vickers Light Tank utilised Carrier tracks, and if so, how many teeth were on its drive sprocket? Also was the Vickers fitted with Pommy or Oz track?

Bob

[Richard Farrant]

Originally Posted by Bob Moseley

Also was the Vickers fitted with Pommy or Oz track?

Bob,


The Vickers Light Tank pre-dates Australian LP carriers so would be fitted with British tracks (Pommy as you say). I think this was discussed recently with Colin, but I seem to recollect the Light Tank had a slightly wider track fitted, according to an amendment in the manual dated about 1937, and also think that it is wider than a British carrier track. Can find no mention of number of teeth on the sprocket though.

[gordon]

... doesn't happen often so I thought I'd share it - maybe someone has even mentioned it before.

If you were starting to build this thing, and you had the standard chassis, transmission, diffs, wheels and tracks on the shelf, the obvious difficulty is matching the wheel drive ratio to the tracks, as per all the above discussion.

There's also been a lot of chat about the track sprocket tooth number, but wouldn't it have been a simpler option, at time of original production, to make one or more special pairs of drive sprockets with slightly different diameters and numbers of teeth? Obviously you would start by knowing what the front drive roadspeed should be, but specially-made drive sprockets would let you match or iron out any variations, within the limits of being too small for the tracks to run round or so big they hit the 'body'

Build it first, with standard carrier drive sprockets, and try it with the front axle out of gear, then measure it, then fit track sprockets with extra or less teeth till it's a perfect match with the front axle in drive?

Oh, and I hope it's going to get a real body and not that collection of concrete blocks like the original did in the photo.


Good luck.

[Lynn Eades]

I would think that the steer axle would do all the steering (is that the case with other half tracks?) and that there would be no need for any steering control at the rear. KISS applies.

Charlie, There would be a lot of reasons to have the drive axle at the front of the track. The drive axle is solid mounted in the chassis, making the hookup of diff to t/fer case relatively simple.

[Bob Moseley (RIP)]

Hi all
Thanks for all your comments so far, they are extreemly helpful. As this is a faithful reproduction I am using the standard 10.50x20 directional tyre. My measurement is off my one worn example with a tape measure around the highest point on the tread. So the 129" circumference would be the minimum. The 77" track distance was measured with the track coiled and counting 43 sprocket holes. Again this is only an approximate measurement. However as both measurements would be within cooee of the original measurements I don't think the discrepancy would matter.

Boob, your theory relating to the second transfer case flipped is exactly the same as Tony's and my other guru, Lawrie Winney.

The quandry now is, one transfer case or two with the second one reversed, bearing in mind that this would only apply if 4wd was utilised.

Re. the steering, I am happy to rely on the steer axle at this stage. However if that doesn't work I may introduce steering rods that connect between the tie rod ends and the brake actuation levers in the brake drums. However to do this I would need to obtain the backing plates off the Ford C81T (1938 Ford Commercial, the barrel nosed one) as they operated on cable brakes and were utilised in the Australian Carriers. However my limited stock of images doesn't show this adaptation.

OK that's it for now. Time for a red, some choccies and watch the beautiful rain, although the hay makers don't want it at the moment as they are in the middle of the hay season.

Actually Jif, we need a smilie with a glass of red. Just have a look in the 25th hour of your day.

Bob

[Grant Bowker]

According to the AEDB Design Record (I don't have my copy with me right now to quote percentages) there were significant differences in diamater between tires that were nominally the same ("same" size and all cross country) but of different manufacturer. Since I haven't seen specific reference to matching brands as a means to match sizes on a truck I doubt they used that as a method to ensure size match, but I have seen reference to measuring tires to ensure they were all of similar size on a vehicle. If they took the time to tell the maintainers to check, they must have found the size differences among "same" tires to have caused some kind of handling/driving problem.

[Tony Smith]

Originally posted by Bob Moseley
Hi all
Thanks for all your comments so far, ..

Boob, your theory relating to the second transfer case flipped is exactly the same as Tony's and my other guru, Lawrie Winney.

The quandry now is, one transfer case or two with the second one reversed, bearing in mind that this would only apply if 4wd was utilised.

Bob

Bob 1, No, I'm saying that a 2nd case ISN'T necessary. Rear drive is always 1:1 to the carrier bogie, and while the t/case is permanently in Low, the front axle is only engaged when required. This will work irrespective of 2wd/4wd.

Boob 2, I was talking about using the PTO output shaft which always turns 1:1 with the trans input, in fact it's connected to this very same shaft by a dog clutch. The normal rear output shaft cannot be made to run at 1:1 while the front is 1.87 : 1, but the PTO can only ever run at 1:1.
Finding a donor C60X t/case in order to replace the PTO housing will provide a stronger output for the drive to the carrier bogie.

[Tony Smith]

Originally posted by Bob Moseley
Hi all
....However to do this I would need to obtain the backing plates off the Ford C81T (1938 Ford Commercial, the barrel nosed one) as they operated on cable brakes and were utilised in the Australian Carriers. However my limited stock of images doesn't show this adaptation.
Bob

At the Canungra Swap, I bought these NOS carrier backing plates off a bloke who said that he had a shed full of them back at home in Brissie. "Quantity was not an issue". Quite cheap, the price of the linings probably.

[Bob Moseley (RIP)]

Hi All - Look what Ian Fawbert found. All we need to do now is identify the source of this diagram. Talking with the guru Lawrie, he says ADD(X)868 probably stands for Australian Defence Diagram(Experimental)868. Ian states that CVT. in the title of the plate stands for Chevrolet. I had always thought this truck was made late 1942 to early 1943, but the signature on the bottom right gives a date of either 14 or 16/4/44. However Lawrie thinks this diagram could have been made up after the manufacture of the truck, as many were. This could be correct as the description says "Prepared From ADD(X)868, suggesting it was copied from an earlier drawing.

I invite comment/further interpretation.

Once again, a big thanks to Ian.

Update on progress - carrier wheels are being re-rubbered and the Hino truck truck is getting a paint make-over.

Bob

[David_Hayward (RIP)]

Well done all concerned!

Note the GM part #s, so it's definitely a 134" Chevrolet. Do the diff. part #s mean anything please, eg they are from a 4x2 say?

[phoenix]

That is the score of they year I would say, nice work!

[David_Hayward (RIP)]

...agree about that!