Carrier Track Variations

[Jack Geratic]

Hello again Lynn

For sprockets I would like to know for certain if the diameter is the same for the carrier and the Vickers LT VIB. Don't have a measurement for either but hubs are certainly different in detail.

[Lynn Eades]

Hi Jack, I don't know, but Colin J. in Adelaide would surely be able to answer that.
The common models (1941 to 45 U.C.) of the British and Canadian and Australian carriers all have a 35 tooth sprocket and mount on the same p.c.d. on 18 bolts. The Australian sprocket has a shoulder on each side and so is thicker on the mounting face. The interchanging of such means that the foreign sprocket would run on a different centerline (in relation to the bogie wheel centers) (about an 1/8")
Some people do this without worrying about it. I don't know what the long term result would be. Later sprockets changed to try to stop track wear. A sprocket was judged worn out when a section of 1 7/16" bar stock would fit between the teeth (and I suppose contacting the base or root of the sprocket)

Bogie wheels:
A Canadian or British U.C (and prior models) had a bogie wheel, the cast steel rim being 3.0 inches wide. With the Rubber they totaled 20 inches in diameter. The front wheel varied, but was nominally 19 inches in diameter. (the steel wheel remained the same as on the other wheel stations) This 19 inches varied, I have one in good condition clearly marked Dia 18.375"
It looks like the tyres reduce in width from the wheel at a 20 degree angle each side.

The Earlier Vickers Light Tanks used these same wheels, but with the advent of the Mk VIB, the wheels went out to the 3.5 inch width, that the Australians later adopted for the LP1 and later the LP2 and LP2a.

[Jack Geratic]

Lynn much thanks again for providing this information.

Indeed, on page 29 of Colin's thread about his VICKERS MK6B restoration, someone asked specifically if the sprocket was the same as on regular carriers and he responded with a yes. Now just to find a diameter for these.

Will amend my notes about the bogie widths as the values were a bit less from a 20 year old post.

http://www.mapleleafup.net/forums/sh...aussie+pattern

[Lynn Eades]

I can measure a sprocket for you.

[Jack Geratic]

That would be awesome! If you can provide a diameter that includes the teeth and without it would help a lot.

I counted the number of teeth on the newly machined sprocket that Colin created for his Vickers tank. and it too is 35.

[Lynn Eades]

Jack. First of all I edited my previous post where I said they mount on 16 bolts. In fact they mount on 18 bolts. (I should have checked first)
Now that I see your sprocket, I dont know what you are after? The new made one looks to be a copy of a std. Australian one. The only difference with a British or Canadian one is the thickness (no shoulders ) The thickness being 19mm (3/4")
It is hard to measure the root diameter because a gap on one side lines up diametrically with a tooth on the other side. The answer would be to swing it in a lathe, but I cant do that. So my estimate would be 474mm. Does that help?

I have a few NOS Australian sprockets, but they are buried and very greasy. Not fun to deal with.

[Jack Geratic]

Hi Lynn, yes just trying to obtain the sprocket diameter in relation to the bogie.

All I can do is guesstimate on a photo, scaled so the bogie diameter is 20 inches. Sprocket diameter including the teeth looks to be about 25 to 25 1/2 inches but must be a bit less than this because the photo is slightly angled such that the sprocket is closer to the camera/viewer.

[Lynn Eades]

Hi again. The overall dia of the sprocket is about 525mm dia. (20 11/16 ish) (max dia.) The bore is probably 16" (406.5mm ish?)

That sprocket (your pic) looks like a later type Canadian one with integral shoulders to carry the track better. (reduce wear) The LP2 / 2a. later had bolt on supports (I've only seen the drawing in a manual) probably similar to the Loyd carrier ones.

What are you trying to achieve? If I knew that, it would make sense to me and what I write might be more useful to you.

[Lynn Eades]

Jack, I was just looking at yor photo post #36. Shouldn't the sprocket sit on a shoulder (spigot?) They are usually a tight fit to stop the sprocket walking on the bolts?
Do you have one of the Vickers Light Tanks?

[Jack Geratic]

Hello Lynn

Both those photos are of the Vickers Light Tank sprockets. The newly machined one is from Colin Jones showing his handiwork while the cropped image of a brightly painted vehicle is from a museum.

Another photo from Colin's progress showing the attachment point for the light tank sprocket



My intention overall was to confirm that the sprockets and bogies are the same diameter for both the VI light tanks and carrier which I believe has already been established. The reason for wanting to know actual diameters is to ascertain how accurate the scale kit manufactures have provided for these two particular subjects.