1943 2 1/2 Ton Federal 2G Questions

Military Trucks 2 1/2 ton and greater, Wanted, For Sale (NO AUCTION or EBAY), and Knowledge Base

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kw573
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Re: 1943 2 1/2 Ton Federal 2G Questions

Post by kw573 » Wed Mar 25, 2020 2:47 pm

Hi all,

Mudflap,
From my experience in diffs in cars, light trucks and mid-sized trucks, I believe you are correct. And the same principles apply for even huge units from what I have seen.

Dozerman51,
The common syncro design works as the gear is being engaged, regardless of an up-shift or down-shift.

I crash-shift all the 969 changes as I can only manage around 50% 'clean' shifts despite double clutching and being reasonably capable on Road Ranger boxes. In the 969, I'm a long way from the clutch-less 'soft-shift'!! :?

Have a nice day.

Sam.
1942 Script GPW (Daily driver).
Willys MB.
2 x Diamond T 969.
Kenworth M1A1 Heavy Wrecker.
3ton GS (Blitz) Trailer.
150gal water tanker trailer.

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Re: 1943 2 1/2 Ton Federal 2G Questions

Post by Joe Gopan » Wed Mar 25, 2020 3:29 pm

The Clark 204 Transmissions are a "sliding gear" type, no synchros.
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Re: 1943 2 1/2 Ton Federal 2G Questions

Post by kw573 » Wed Mar 25, 2020 4:10 pm

From what I've seen,

Non-syncro transmissions move or 'slide' the gears into and out of mesh = "sliding gear" type.

Syncro-mesh types have the gears permanently engaged but floating on the main shaft and are selected by a sliding drive ring/hub which is splined to the main shaft and into which is housed the syncro mechanism.

Hope we are not getting too far off topic.

Sam.
1942 Script GPW (Daily driver).
Willys MB.
2 x Diamond T 969.
Kenworth M1A1 Heavy Wrecker.
3ton GS (Blitz) Trailer.
150gal water tanker trailer.

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Re: 1943 2 1/2 Ton Federal 2G Questions

Post by Joe Gopan » Thu Mar 26, 2020 9:54 am

Sliding Gear Transmission is standard Army Lingo for that type transmission. In my day army mechanic days trucks having the Clark 204 and 205 Gearbox were introduced to us as having a "sliding gear transmission". The CCKW and GMC Model 424 were still in motorpools and used the Clark gearboxes similar to the Federal 2G.
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Re: 1943 2 1/2 Ton Federal 2G Questions

Post by mudflap » Fri Mar 27, 2020 12:28 am

At a high level, manual transmissions mainly fall into one of two categories: Sliding gear, and constant (aka continuous) mesh.

As mentioned previously, in a sliding gear transmission, drive and driven gears are not engaged until they are actually moved horizontally, or "slid" on a shaft to engage them with other gears.

As also mentioned, in constant mesh transmissions, the gears on the main shaft are continuously engaged with their counterparts on the countershaft. In neutral, they free wheel on the main shaft, and engagement is achieved by sliding a dog (aka hub), that is splined to the main shaft into engagement with the desired gear. This locks the gear to the main shaft, and allows power to flow through the transmission.

Constant mesh transmissions come in two types, synchronized and unsynchronized. In synchronized transmissions, the dog is called a hub, and is splined to the main shaft. Instead of moving the hub, gear engagement is achieved by sliding a sleeve, which is splined to the outside of the hub, over a set of teeth on the gear. In between the sleeve and the gear, is a device called synchronizer. During a shift, the synchronizer acts as a cutch, matching the relative speed of the gears (or "synchronizing" them). The example I often use to explain this concept is a kid riding a bike next to a picket fence with a stick in his hand. If he tries to shove the stick into the fence, it will chatter. However, if you could speed up the fence to the same speed as the bike, the stick could easily be inserted into the fence.

While the Clark 204-VO is called a sliding gear transmission, it is really more of a hybrid - as the 5th gear is in constant mesh with the countershaft, and is engaged by a dog, not a sliding gear. Maybe they figured that since the majority of the gears are sliding gears, they would just call it a sliding gear transmission.

To illustrate this point, an image of a 204-VO-273 is attached below.

BTW, in comparing the specs for 204-VO-320 in the Federal with the 204-VO-273 in the CCKW, the shift pattern and gear ratios are identical. I'm wondering if maybe the -320 on the Federal could have a speedometer drive, which would account for the different suffix?

Best Regards....


Clark Transmission.jpg

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Re: 1943 2 1/2 Ton Federal 2G Questions

Post by Joe Gopan » Fri Mar 27, 2020 8:35 am

The Truck in question is the Federal @G, I will include another Truck most are familiar with the CCKW as both have the CLARK 204 VO transmission which is a 5 Speed with overdrive in 5th Gear. The TM for Clark Transmissions is TM9-8611 Ordnance Maintenance, Transmissions(Clark Equipment)
I'll quote from description and data paragraph of that TM.

"The Transmissions in this chapter are of the constant-mesh.selective gear type having one reverse and five forward speeds.The gears are selected, or shifted,manually by means of sliding shafts with attached forks and lugs which are supported in, and inclosed by, the shifter shaft housing attached to the top of the transmission case."

That doesn't say much about Sliding gears. My army wheeled vehicle experience included training classes on the DUKW, CCKW, the 1955 GMC 424V Commercial Truck with the 270 Engine and 5 Speed Clark. The TM's for these vehicles all refer to "Selective Sliding Gear type"
The different Instructors all referred to these trucks as having "Sliding Gear Transmissions" which is how most referred to them.
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Re: 1943 2 1/2 Ton Federal 2G Questions

Post by Tesfallout » Sat Mar 28, 2020 9:24 pm

Is there any good way to figure out what the military numbers on the old truck used to be? Most of them, I can make out, but the ones on the front of the hood are pretty much gone.

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Re: 1943 2 1/2 Ton Federal 2G Questions

Post by Joe Gopan » Sun Mar 29, 2020 7:42 am

Can you post what you have? I'll try to fill in the blanks.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
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Re: 1943 2 1/2 Ton Federal 2G Questions

Post by Tesfallout » Mon Mar 30, 2020 7:48 am

Both the Driver's and Passenger's side have a large "25" printed just in front of the door.
DriverSide.jpg
Both the Driver's and Passenger's side have "U.S.A. 4457565" printed on the hood, though the passenger side is almost illegible.
DriverHood.jpg
And here's the best panorama I could get for the front of the hood.
Front.jpg

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Re: 1943 2 1/2 Ton Federal 2G Questions

Post by johnseidts » Mon Mar 30, 2020 11:32 am

Excellent find on the registration number! So what is the condition of the JXD?
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Re: 1943 2 1/2 Ton Federal 2G Questions

Post by Tesfallout » Mon Mar 30, 2020 1:01 pm

I believe that the engine will run, but I am currently getting ready to clean the engine bay to see what I'm dealing with. From what I understand, the water pump leaked and caused the old distributor to lock up with rust. I know I need a compatible distributor and water pump, then I've got to fix the old hoses and a bit of wiring. Hoping that this one runs well, but I do trust the guy I bought it from when he says it will run.

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Re: 1943 2 1/2 Ton Federal 2G Questions

Post by Tesfallout » Mon Mar 30, 2020 7:57 pm

So, doing some digging on the numbers, it appears that this truck might* actually be a 1944 model. I found some documentation saying that the "Summary Report of Acceptances, Tank-Automotive Material, 1940-1945" from Detroit Ordinance showed a total of 260 1944 models brought in. Does anyone know where or how I might be able to find a copy of that report to see if it has more information available?

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Re: 1943 2 1/2 Ton Federal 2G Questions

Post by Joe Gopan » Sat Apr 04, 2020 9:06 pm

The Federal 2G has a rare TM. TM9-821x is X-Extracted from TM9-821 It has driver operating and maintenance and vehicle data.
It is in a 4-1/2 X 7 layout. This TM, if you can find one is very collectible.
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HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
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Re: 1943 2 1/2 Ton Federal 2G Questions

Post by gerrykan » Sun Apr 05, 2020 9:00 am

Tessfallout,
You may want to research "electrolysis rust removal" to free up the distributor.
It does an amazing job on some items.
I don't remember if it affects brass, aluminum, etc, so do your research as a distributor often has brass/bronze bushings.
Roy

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