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I figured I'd open a new thread for this.

Here is a couple of outakes regarding the 'basic' T95 suspension from 1958 document.







Regards
Don

The 1958 data sheet on the T95 which mentions two types of track, the T114 & T115.



Regards
Don

Here is a sample of the diffeent variants of T95, beside the 'usual' ones.....













Regards
Don

Hi,

Moved from the Ft. McCoy thread:

- Kurt_Laughlin

The T114 track was for "Tanks T95, T96, T110 and other vehicles having similar suspensions" according to OCM 36316 (20 SEP 56) that assigned the nomenclature. T114 track was double pin with rubber bushings, hence live. It is listed as being lighter than the T108 and T109 which were for the same vehicles. They were live tracks as well.

T108 - Replaceable rubber chevron grousers
T109 - Replaceable steel grousers
T114 - Integral rubber chevron grousers

KL

Live? Are you sure? It doesn't look 'live'...no end connectors. It looks to me like a scaled-up version of the M113 track, which I'm pretty sure is not 'live' track. I think the rubber bushing reduces the squeak and protects the pins. I could be wrong...

{Added: From Dontos first post here: "...flat-track type suspension..." = non-live track. I think I prefer "flat" to "dead" and will use it that way.}

As for Doug's question about return rollers, I'm not sure that they are indicative of track type except that the lack of them usually indicates 'flat' track. On the other hand, many WWII German and Soviet vehicles had return rollers with flat (non-live) track. It may be related to the allowable stresses on the drive sprockets and idlers? Better post war designs could handle the lateral/shear stresses of the unsupported return run of track, where previous examples could not?

I know that the US went with live track early-on, which improved track retention at high speeds. It seems that when weight became an issue (M41, M551, M113) the designers went back to flat track though.

Interesting discussion!

C

Live is my presumption for rubber bushed track. As best I can tell the US hasn't used any "dry pin" or dead tracks since WWII. BTW, "flat track suspension" means no return rollers, regardless of the design of the track blocks itself, don't interchange flat and dead Most German WWII and Soviet tracks until the 1980's were dead. Other than the Pz I through IV and the KV and IS series, all the suspensions in that period were flat.

The main reason for using live track is to reduce rolling resistance. Because the track wants to curl around the wheels alread, it takes less power to move them.

The M113 used T130 tracks, which were single pin with rubber bushings. The rubber was bonded to the hole in the track and to a steel liner with a hexagonal hole that was positioned just so. The track pins were hexagonal, so the orientation of the tracks to each other was fixed.

I suggest anyone interested in this stuff to get or read "The Technology of Tanks" by Richard Ogorkiewicz (sp?). A great two volume book. [EDIT - Good golly! I just checked on Amazon and used copies are going for $850!!!. It was "only" $105 when I got mine back in '91 or '92.]

KL

- C_Sherman

Hi,

Live? Are you sure? It doesn't look 'live'...no end connectors. It looks to me like a scaled-up version of the M113 track, which I'm pretty sure is not 'live' track. I think the rubber bushing reduces the squeak and protects the pins. I could be wrong...


C

Re: M113 track...at least the original stuff...laid stone flat on the ground, easy to bend and of course, mount (you could pull the track on by hand once you had the road wheels on the track). I can't say about some of the later stuff, like Diehl(?) track. I have pics of later M113's with an end connector type track...that might be "live"...can't say.

Sorry to open a can of worms, but this "live/dead/flat" and "supported/unsupported" issue has been bothering me for a while (you could say, forty years or so). I'm not sure there is a definitive answer, but there must be some conventions*. Kurt?


*Only one I'm pretty sure of is that "live" track has bushings that "encourage" the track to bend "inwards" to assist it's travel around sprocket and idler's and thereby to keep the track where it's supposed to be. Beyond that, it gets real fuzzy for me in some cases.

- Kurt_Laughlin

Live is my presumption for rubber bushed track. As best I can tell the US hasn't used any "dry pin" or dead tracks since WWII. BTW, "flat track suspension" means no return rollers, regardless of the design of the track blocks itself, don't interchange flat and dead Most German WWII and Soviet tracks until the 1980's were dead. Other than the Pz I through IV and the KV and IS series, all the suspensions in that period were flat.

The main reason for using live track is to reduce rolling resistance. Because the track wants to curl around the wheels alread, it takes less power to move them.

KL

Live track is simply track that, by some mechanical means (usually a wedge bearing on machined surfaces on the track pins), incurs a tendency to curl inward when 'relaxed'. Flat track lays flat.

Design differences aside, there is no functional difference between WWII German track and the track on the M113. The rubber bushings are a refinement, not a fundamental engineering change.

Live track may reduce rolling resistance, but cannot reduce power requirements. Basic physics: TANSTAAFL. The major advantage of live track is a resistance to shedding at high speeds, because the track naturally prefers move around rather than away from an idler or sprocket. The curl helps the track to maintain contact and overcome centripetal forces that pull it away from the wheel. Live tracks generally require return rollers to avoid overstressing the track by bending it 'backwards' on the top 'return' runs. Such bending increases the risks of broken track pins, which require replacement and defeat the purposes of using the live track in the first place.

The advantages of flat tracks are in the manufacturing process and in the maintenance requirements, and thus costs. Live tracks require a certain amount of (relatively) precise machining in manufacturing, and can be more difficult and resource intensive to maintain. Flat tracks don't require the level of precision or manufacturing effort that live tracks do, and are (relatively) easier to maintain in service.

Flat tracks may or may not use return rollers, because they are able to bend 'backwards' to some extent, without problems. Modern tendencies are to use larger roadwheels and allow the track to touch or nearly touch the tops of them. (The WWII Germans tried it both ways and seemingly preferred no return rollers with their later designs.)

I'm just a dumb ol' engineer, and I didn't write no books. But this stuff I 'get'. A curious tanker that asks a lot of questions in engineering school can learn a lot,and I did!

Chuck

Chuck

WOW!! That is an excellent descriptive. I think I even understand that.


I'm actually learning something new here.

"Training has taken place"
Thank you
Don

Well, somebody wanted nomenclature conventions and that's what they are.

Flat Track Suspension - Return run of track supported by the tops of the road wheels.

Dry Pin Track = Dead Track – Tracks with pins that float freely within the track blocks. “Dead” is also used to describe worn tracks where the bushing in “Live” tracks no longer maintains the proper angular orientation between adjacent blocks.

Rubber Bushed Track = Live Track – Tracks with pins that are fixed in relation to the track blocks. "Rubber bushings eliminate metal-to-metal contact between the pins and the links and the necessary angular movement between them is provided by torsion of the rubber, the outer surface of the bushings being fixed to the links and the inner surface to the pins." (TOT)

I’ve attached a scan from a TM showing the M113 track block.

i75.photobucket.com/al...1track.jpg

As you can see, the pin and the bushing hole are both hexagonal. A hexagonal pin in a hexagonal bushing hole means the pin cannot rotate relative to the bushing. If the theory is that the T130 tracks are “dry pin” types, then the obvious question is, why go to the added expense? If the theory is that the T130 tracks are “dry pin” types, then the bushing must be free to spin within the track block. If that is true, why was it necessary to place the adjacent blocks at a 20-degree angle when reconnecting track?

KL

Kurt

Pulling something from my 'endless bag of tricks', here is a couple of photos of a track block from an M113, that I just happen to have available here at home......





It is amazing the assortment of items one collects over the years.

Regards
Don

Hi Folks! Sorry I am so late to the party.

Looks like Kurt needs some back up and I am here to do that.

While I don't have Dr. O's books that Kurt suggest reading, I do have Armoured Forces, A History of Armoured Forces and Their Vehicles and Design and Development of Fighting Vehicles by the good Doctor.

Who is Dr. Richard M. Ogorkiewicz?

"....is an internationally recognized expert on armour." and "....is an internationaly recognised authority on ..(AFVs)..and has lectured on the subject in Britain, ..United States, Sweden and Israel."

When it comes to the design of AFVs this was the man to go to during his time.

There are three types of track used on AFVs,
1. Band track, rubber with steel cables inside. examples US Halftracks, M50, M56, M114. Works well on smaller AFVs.

2. DEAD track block. Note this is a type of block used to make up a track.
examples: just about every Soviet tank up until they started using Live track block during the mid Cold War era. Most tracked vehicle designs started out with dead type track block and the Soviets stuck with it. The tank would be destoryed before the short life of that type of track was reached. It was a lot easier to teach Ivan how to take it apart and put it back to together. Remember most Ivan tankers came from a farm where horse powered equipment was the standard. Dead track block was just like hooking up a team of horse to a plow or wagon. It can be made faster and it cost less than live block.

3. Live track block, Note again, this is a type of block used to make up a track. Examples: Every US light and medium tank from the mid 1930s up to now. It cost more to make, needs more care, but it last a lot longer than dead track block.

To Chuck, "It doesn't look like 'live' track, no end conectors.
Sorry but end connectors have NOTHING to do with live track. Track block with end connectors is a type of live track. That T95 has a live track and the M113 has a live track.

Don't know what type of track block you are looking at, check the rear of hull where the track begains the return to the front. It the block is dead, there will a wedge block that will push the dry pin back into the dead blocks.

Sorry Doug!
If your M113 track layed flat and the end blocks did not lift up off the ground, then that track was dead or dying and needed to be replaced. For the most part very little new track was shipped to the RVN. Track was removed at the depots from vehicles that where being shipped out for rebuild and that used track was shipped to the field. It is a case of most vehicles would be damaged/destroyed before the track died. No need to waste new live track block.

Back to Chuck:
Your "I prefer 'flat' to 'dead' and will use it that way." doesn't work.
That is the same as saying I perfer Applies to Oranges and will use Applies anytime I see an Orange.

DEAD or dead track is a TYPE of track block, FLAT Track is a feature of the 'Christie' tracked suspension system. It has nothing to do with the type of block used.

A comment about 'Christie suspension'.
Dontos your are correct, the T95 has a 'MODIFIED Christie suspension'.
The M114, M551, the M107/110 hulls, the T55 and T62s all have 'MODIFIED Christie suspensions'. The T34 Family of vehicles, T54 and most of the British Crusier tanks up to the Comet have true 'Christie suspensions'.

Vehicles with a Christie or Modifed Christie don't have support rollers so the road wheels have more room to move upward.

It is sad that we lost the old site. This subject came up back in June of 2000.
Spot report! Passed my bed time, see you folks later.
Sgt, Scouts out!

- Roy_A_Lingle

Hi Folks! Sorry I am so late to the party.


Sorry Doug!
If your M113 track layed flat and the end blocks did not lift up off the ground, then that track was dead or dying and needed to be replaced. For the most part very little new track was shipped to the RVN. Track was removed at the depots from vehicles that where being shipped out for rebuild and that used track was shipped to the field. It is a case of most vehicles would be damaged/destroyed before the track died. No need to waste new live track block.

Sgt, Scouts out!

No doubt. I replaced three road wheels on "Head Shoppe" and you should have seen what came off. Only one replacement was "new", the others were just "not as bad" as what was on there. Only had to retrack once and it was flat as a pancake. My pics of X-Ray's little incident in the field don't show the track due to the heaviness of the bush, but it was the same way.

Here's a shot of a Sheridan track, most likely salvage from a "beyond repair" vehicle.

Hi Doug! Hi Folks!

Great shot! Notice how the last track shoe near the hull is lifted off the ground. That LIVE track still has a bit of life left in it.

The Long Bin Depot would set that track aside and when needed ship some of or all of it out to a unit requesting some track. The vehicle would get shipped out of county without the tracks.

Spot Report!
Sgt, Scouts out!

Roy said:

Track was removed at the depots from vehicles that where being shipped out for rebuild

Flash forward 25 years to Fort Irwin and you'd have the same situation with the M551's there. Crewed them from 87-89 and we drove the crap out of them. Combine that with the fact that most parts production had been halted years ago and all we would get was war stock/ rebuild/ refurbished you'd get some pretty interesting deliveries. The only other unit that used them by then was 3-73 Armor at Fort Bragg. When a tank was coded out (warped/ cracked hull ) it was stripped. Officially we could send them off with just 4 road wheels and arms. Unofficially we would also exchange every working part we could for broken ones if the item was required for turn in. Short of a hull being cracked/ warped we would fix them up ourselves. Track and sprockets were in serious shortage for a while. Pretty bad when exchange criteria was either one of the center guides was broken on a block or the bushings were so wore out the nut on the track pin was damaged and a socket wouldn't fit on it. Right before I left they started sending us war stock track and they also started the M551/OPFOR model production at Anniston.

Point was, you could definitely tell when you had dead block track. The noise of it slapping on the hull was very obvious when doing 35-40 MPH in the Desert while you prayed it didn't snap !!! 324 (C24) did and she flipped ass over nose when what was left of the track bunched up.

- Roy_A_Lingle

It is sad that we lost the old site. This subject came up back in June of 2000.

Sgt, Scouts out!

I would have missed it anyway, as I don't think I found the DG for a couple more years, maybe three.

The Wayback website might have some of that stuff archived, but then again, maybe not. The old site became untenable anyway so it's not as if we had a choice.