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Twin Disc TD61-1177 and Twin Disc 8-FLW-1750 torque converter

tooFATtoDRIVE

New member
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Location
Switzerland
Hi all,

I am looking for any technical info regarding these components: Twin Disc TD61-1177 and Twin Disc 8-FLW-1750 torque converter

These were mounted in ATC Tatra 6x6 firefighter trucks (when they were sold in the US) and also in military trucks (https://www.armedconflicts.com/CZE-Tatra-815-6MWR27-26-298-6x6-1R-t158909).



Twin Disc for wheeled vehicles are pretty much unknown in Europe and I have been having trouble getting any technical data and overall opinion on long-term reliability, in particular compared to Allison automatic transmission offering.

I would be grateful for any help with getting tech data.

Thanks
 

Geof

New member
7
8
3
Location
Merrill, WI
Hi all,

I am looking for any technical info regarding these components: Twin Disc TD61-1177 and Twin Disc 8-FLW-1750 torque converter

These were mounted in ATC Tatra 6x6 firefighter trucks (when they were sold in the US) and also in military trucks (https://www.armedconflicts.com/CZE-Tatra-815-6MWR27-26-298-6x6-1R-t158909).



Twin Disc for wheeled vehicles are pretty much unknown in Europe and I have been having trouble getting any technical data and overall opinion on long-term reliability, in particular compared to Allison automatic transmission offering.

I would be grateful for any help with getting tech data.

Thanks
[
 

Geof

New member
7
8
3
Location
Merrill, WI
Hello,

Yes, I am very familiar with the TWIN DISC transmission installation in the TATRA chassis. I am confident we have TD installation drawings for the TD61-1177 transmission and 8-FLW-1750 T/C. I am Chief Engineer at ISLAND CITY ENGINEERING in Merrill WI. IC has installed multiple TD transmissions with TATRA and US chassis including the TD61-1183, TD61-1175, TD61-1177 and others.

I assisted American Truck with the IMOD 6X6 and LVSR 10X10 programs. In about 2007 IC retrofit a FMTV chassis over a TATRA chassis (photo attached) using a TD61-1187 transmission. IC builds the FASTII High Mobility Trailer usining the TATRA suspension (photo attached).

IC is a factory authorized TATRA distributor and Engineering provider specifically for homologation to US FMVSS.
 

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Mullaney

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Hello,

Yes, I am very familiar with the TWIN DISC transmission installation in the TATRA chassis. I am confident we have TD installation drawings for the TD61-1177 transmission and 8-FLW-1750 T/C. I am Chief Engineer at ISLAND CITY ENGINEERING in Merrill WI. IC has installed multiple TD transmissions with TATRA and US chassis including the TD61-1183, TD61-1175, TD61-1177 and others.

I assisted American Truck with the IMOD 6X6 and LVSR 10X10 programs. In about 2007 IC retrofit a FMTV chassis over a TATRA chassis (photo attached) using a TD61-1187 transmission. IC builds the FASTII High Mobility Trailer usining the TATRA suspension (photo attached).

IC is a factory authorized TATRA distributor and Engineering provider specifically for homologation to US FMVSS.
.
That trailer would be really nice to have...
Is there any chance that the general public could be the proud owner of one?
 

tooFATtoDRIVE

New member
12
12
3
Location
Switzerland
Hello,

Yes, I am very familiar with the TWIN DISC transmission installation in the TATRA chassis. I am confident we have TD installation drawings for the TD61-1177 transmission and 8-FLW-1750 T/C. I am Chief Engineer at ISLAND CITY ENGINEERING in Merrill WI. IC has installed multiple TD transmissions with TATRA and US chassis including the TD61-1183, TD61-1175, TD61-1177 and others.

I assisted American Truck with the IMOD 6X6 and LVSR 10X10 programs. In about 2007 IC retrofit a FMTV chassis over a TATRA chassis (photo attached) using a TD61-1187 transmission. IC builds the FASTII High Mobility Trailer usining the TATRA suspension (photo attached).

IC is a factory authorized TATRA distributor and Engineering provider specifically for homologation to US FMVSS.
It would be amazing if you could check for any docs regarding the TD61-1177 transmission and 8-FLW-1750 T/C. Thanks
 

Geof

New member
7
8
3
Location
Merrill, WI
.
That trailer would be really nice to have...
Is there any chance that the general public could be the proud owner of one?
Yes, the FASTII is available for commercial sale. I will attach a flyer and a link to Army testing video in Nevada.

This video is also available at the ISLAND CITY website: www.islandcity.us
 

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Last edited:

Geof

New member
7
8
3
Location
Merrill, WI
Good morning!

Can you tell me a bit more on what you need for the TD61-1177 transmission for the IMOD. I have located the hydraulic installation schematic, and electrical installation drawings. I should have the physical installation drawing today. Is this for a TATRA related project?

All the best

ISLAND CITY

Geof
 

tooFATtoDRIVE

New member
12
12
3
Location
Switzerland
Good morning!

Can you tell me a bit more on what you need for the TD61-1177 transmission for the IMOD. I have located the hydraulic installation schematic, and electrical installation drawings. I should have the physical installation drawing today. Is this for a TATRA related project?

All the best

ISLAND CITY

Geof
Hi,
I have seen the below truck for sale. It is formerly ATC truck (if the seller is correct) so it has the Twin Disc TD61-1177 transmission and Twin Disc 8-FLW-1750 torque converter. The seller has absolutely zero knowledge of this truck. He mentioned it had an Allison transmission but that's incorrect. I am not surprised with the seller's lack of knowledge, it is just a truck flipper (as I tend to call this sort of business).

As mentioned initially, Twin Disc is super rare in Europe and I have struggled to find info. I tried some Czech forums but aside from the transmission name, which is known, nobody has any knowledge of it.

I hope it helps.



 

Geof

New member
7
8
3
Location
Merrill, WI
Hi,

Ok, now I understand.

This could be a ATC chassis, however I notice a few things that may not indicate this.

All of the BLM firetrucks were originally integrated at S&S Fire, a company located in Gas City, Indiana. S&S went out of business about a year after the TATRA truck sale to the BLM. This caused problems, because, of course it was their truck. The Bureau of Land Management had problems having the trucks serviced as a result.

1) I notice that the fuel tank is on the opposite side of the S&S trucks when equipped with the 4-door cab. It could have been moved when the fire package was taken off, but that would put the exhaust outlet right behind the fuel tank. It could also have been an early truck, or a chassis not sold or configured differently.

2) I can see the bottom of the TD transmission sticking out, visible below the fuel tank.

3) A small matter, but the grill badge is TATRA all the BLM trucks and IMOD trucks have an ATC grill badge.

3) If you had some photos of the inside of the cab there would likely be some left over controls from fire apparatus.

As far as the Twin Disc TD61-1177 transmission and remote mount 8-FLW-1750 TC, it is a drop-box style transmission TD developed for the unique TATRA central tube frame and drive-line. The transmission bolts directly into the frame tube becoming a structural component. The TC bolts to the engine with a wet flywheel housing, there is a prop-shaft from the TC to the transmission input shaft. The drive-lines fit directly front and rear attach to the transmission outputs with a spline coupling.

It is a very compact transmission installation. There are 3 high-power PTO located on the backside of the PTO where the transmission charge pump, bell-housing scavenge pump and ancillary systems hydraulic pump(s) are located.

There are other TD transmissions ATC used with the TATRA chassis. Twin Disc transmissions generally have a rather large bronze data plate located near the bottom of the housing if you have a chance to look for it.

The truth is that Twin Disc transmission are not commonly used in trucks in the United States or Canada! They are limited to special applications. The US military uses and has used for a long time almost exclusively ALLISON transmissions for logistic trucks.

There were some transmission problems reported with trucks in-service with BLM, from my observation they resulted from poor transmission/torque-converter plumbing integration/installation rather than the transmission itself. I personally managed test vehicles equipped with the TD61-1183 TD drop-box type transmission during grueling testing for the USMC. The TD transmission performs very well. The TD61-1187 transmission system in a TATRA chassis successfully completed USMC first-article-testing including two vehicles undergoing a 20,000 mile whole-life reliability evaluation during the LVSR 10X10 competition. I think an issue arises when service personnel unfamiliar with the TATRA chassis must remove the transmission for service. It is not particularly difficult, but it is necessary to split the frame tube flanges away from the transmission for removal. Service personnel in the US are simply not accustomed or properly equipped. We have split ATC fire and IMOD 6X6 trucks here at IC. It is important that the transmission/TC plumbing integration supports transmission R&R. I attached a photo of the TD61-1177 tranission below the inspection hatch in a ATC IMOD 6X6.

I received the installation Engineering data package for the transmission and torque converter used in the ATC IMOD 6X6 and ATC BLM trucks today from TD. I think maybe what is more important for you is perhaps Twin Disc, and TATRA service and operating manuals?

All the best

Geof
 

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tooFATtoDRIVE

New member
12
12
3
Location
Switzerland
Hi Geof,

Many thanks for your super interesting commentary and technical info.

With regards to the TATRA service and operating manuals this is a no-go with Tatra in Czech Republic. They consider these to be their intellectual property and they do not share it unless you buy a truck. I tried to search for that data online but no luck whatsoever. Additional issue, perhaps, is that these trucks were made for the US market. Personally, I have not come across of a similar truck in Europe.

With regards to the Twin Disc, and TATRA service and operating manuals this is a no-go with my local agent/dealer. This product was never offered over here so the support simply does not exist.

The seller is less than helpful. They could not be bothered to take extra pictures. You mentioned a rather large bronze data plate located near the bottom of the housing - well the seller could not be bothered if it is there or not. It is just a truck-flipping business, not there to help people etc (this is very common in Europe, I experienced it with the German, Dutch and now Lithuanian dealers). With Covid restrictions I am not interested in travelling to them to inspect the truck. Also, with their asking price, they have absolutely no chance of selling it, in particular given how rare is that truck and the transmission solution used.

I will just let it sit tight until normal travel resumes in Europe (2022 maybe) and then decide whether to travel to the seller and see the truck.

The truth is that Twin Disc transmission are not commonly used in trucks in the United States or Canada! They are limited to special applications. The US military uses and has used for a long time almost exclusively ALLISON transmissions for logistic trucks.
Thank you for providing this narrative explaining why the Twin Disc transmission are not commonly used in trucks in the United States or Canada. However, if we only talked about technical solutions, reliability (sort of engineering talk), how would Twin Disc and Allison compare? Would one be better than another? Would they be comparable or this is apple/orange dilema?

On a side note, my ideal truck would be what you see in the pictures linked above but in the 8x8 version. I have not seen one in Europe, other that Tatra 816 Liwa prototypes (see YT vids below) but these were based on the earlier Tatra 815 chassis.




 

tooFATtoDRIVE

New member
12
12
3
Location
Switzerland
As far as the Twin Disc TD61-1177 transmission and remote mount 8-FLW-1750 TC, it is a drop-box style transmission TD developed for the unique TATRA central tube frame and drive-line. The transmission bolts directly into the frame tube becoming a structural component. The TC bolts to the engine with a wet flywheel housing, there is a prop-shaft from the TC to the transmission input shaft. The drive-lines fit directly front and rear attach to the transmission outputs with a spline coupling.
Geof, do you know whether the integrated transfer case is one or two gear setup? I.e. does it have low and high gear? For example, the current Tatra product line offers an Allison transmission mounted together with an engine and then linked by a driveshaft to either single gear or two gear transfer case. From my research into TwinDisc I had not found any mention of this intergrated transfer case having lower and higher gears.

There were some transmission problems reported with trucks in-service with BLM, from my observation they resulted from poor transmission/torque-converter plumbing integration/installation rather than the transmission itself. I personally managed test vehicles equipped with the TD61-1183 TD drop-box type transmission during grueling testing for the USMC. The TD transmission performs very well. The TD61-1187 transmission system in a TATRA chassis successfully completed USMC first-article-testing including two vehicles undergoing a 20,000 mile whole-life reliability evaluation during the LVSR 10X10 competition. I think an issue arises when service personnel unfamiliar with the TATRA chassis must remove the transmission for service. It is not particularly difficult, but it is necessary to split the frame tube flanges away from the transmission for removal.
Would the usual oil/filter change require splitting the Tatra backbone tube and the removal of the transmission?


I found one more video of Tatra truck with Twin Disc gearbox:
 
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